Java 4B – Control Structures: Part 2hunka/vyuka/ProgObj/oop_4/Java_4B.pdf · Java_4B – Control Structures: Part 2 ... import import java.util.Scanner java.util.Scannerjava

1

Java_4B – Control Structures: Part 2

Outline4.9 Essentials of Counter-Controlled Repetition4.10 for Repetition Statement4.11 Examples Using the for Statement4.12 do…while Repetition Statement4.13 switch Multiple-Selection Statement4.14 break and continue Statements4.15 Logical Operators4.16 Structured Programming Summary

2

4.9 Essentials of Counter-Controlled Repetition

• Counter-controlled repetition requires:– Control variable (loop counter)

– Initial value of the control variable

– Increment/decrement of control variable through each loop

– Condition that tests for the final value of the control variable

Outline3

// // // // CounterCounterCounterCounter----controlledcontrolledcontrolledcontrolled repetitionrepetitionrepetitionrepetition withwithwithwith thethethethe whilewhilewhilewhile repetitionrepetitionrepetitionrepetition statementstatementstatementstatement....

public public public public classclassclassclass WhileCounterWhileCounterWhileCounterWhileCounter

{{{{

public static public static public static public static voidvoidvoidvoid mainmainmainmain( ( ( ( StringStringStringString argsargsargsargs[] ) [] ) [] ) [] )

{ { { {

intintintint countercountercountercounter = 1; // = 1; // = 1; // = 1; // declaredeclaredeclaredeclare andandandand initializeinitializeinitializeinitialize controlcontrolcontrolcontrol variablevariablevariablevariable

whilewhilewhilewhile ( ( ( ( countercountercountercounter <= 10 ) // <= 10 ) // <= 10 ) // <= 10 ) // looplooplooploop----continuationcontinuationcontinuationcontinuation conditionconditionconditioncondition

{{{{

SystemSystemSystemSystem....outoutoutout....printfprintfprintfprintf( "%d ", ( "%d ", ( "%d ", ( "%d ", countercountercountercounter ););););

++++++++countercountercountercounter; // ; // ; // ; // incrementincrementincrementincrement controlcontrolcontrolcontrol variablevariablevariablevariable by 1by 1by 1by 1

} // } // } // } // endendendend whilewhilewhilewhile

SystemSystemSystemSystem....outoutoutout....printlnprintlnprintlnprintln(); // (); // (); // (); // outputoutputoutputoutput a a a a newlinenewlinenewlinenewline

} // } // } // } // endendendend mainmainmainmain

} // } // } // } // endendendend classclassclassclass WhileCounterWhileCounterWhileCounterWhileCounter

1 2 3 4 5 6 7 8 9 101 2 3 4 5 6 7 8 9 101 2 3 4 5 6 7 8 9 101 2 3 4 5 6 7 8 9 10

4

4.10 for Repetition Statement

• Handles counter-controlled-repetition details

Outline5

// // // // CounterCounterCounterCounter----controlledcontrolledcontrolledcontrolled repetitionrepetitionrepetitionrepetition withwithwithwith thethethethe forforforfor repetitionrepetitionrepetitionrepetition statementstatementstatementstatement....

public public public public classclassclassclass ForCounterForCounterForCounterForCounter

{{{{

public static public static public static public static voidvoidvoidvoid mainmainmainmain( ( ( ( StringStringStringString argsargsargsargs[] ) [] ) [] ) [] )

{{{{

// // // // forforforfor statementstatementstatementstatement headerheaderheaderheader includesincludesincludesincludes initializationinitializationinitializationinitialization, , , ,

// // // // looplooplooploop----continuationcontinuationcontinuationcontinuation conditionconditionconditioncondition andandandand incrementincrementincrementincrement

forforforfor ( ( ( ( intintintint countercountercountercounter = 1; = 1; = 1; = 1; countercountercountercounter <= 10; <= 10; <= 10; <= 10; countercountercountercounter++ ) ++ ) ++ ) ++ )


SystemSystemSystemSystem....outoutoutout....printlnprintlnprintlnprintln(); // (); // (); // (); // outputoutputoutputoutput a a a a newlinenewlinenewlinenewline


} // } // } // } // endendendend classclassclassclass ForCounterForCounterForCounterForCounter

1 2 3 4 5 6 7 8 9 101 2 3 4 5 6 7 8 9 101 2 3 4 5 6 7 8 9 101 2 3 4 5 6 7 8 9 10

6

Fig. 4.3 for statement header components.

for ( int counter = 1; counter <= 10; counter++ )

Increment of control variable

Control variable

Final value of control variable for which the condition is true

forkeyword

Loop-continuation condition

Initial value of control variable

Required semicolon separator

Required semicolon separator

7

4.10 for Repetition Structure (cont.)

for ( initialization; loopContinuationCondition; increment )statement;

can usually be rewritten as:

initialization;while ( loopContinuationCondition )))) {{{{

statement;increment;

}

8

Fig. 4.4 for statement activity diagram.

[counter <= 10]

[counter > 10]

int counter = 1

counter++Determine whether the final value of control variable has been reached

g.drawLine( 10, 10, 250, counter * 10 );

Establish initial value of control variable

Draw a line on the applet

Increment the control variable

9

4.11 Examples Using the for Statement

• Varying control variable in for statement– Vary control variable from 1 to 100 in increments of 1

• for ( int i = 1; i <= 100; i++ )

– Vary control variable from 100 to 1 in increments of –1• for ( int i = 100; i >= 1; i-- )

– Vary control variable from 7 to 77 in increments of 7• for ( int i = 7; i <= 77; i += 7 )

Outline10

// Summing integers with the for statement.// Summing integers with the for statement.// Summing integers with the for statement.// Summing integers with the for statement.

public class Sum public class Sum public class Sum public class Sum

{{{{

public static void main( String public static void main( String public static void main( String public static void main( String argsargsargsargs[] )[] )[] )[] )

{{{{

intintintint total = 0; // initialize totaltotal = 0; // initialize totaltotal = 0; // initialize totaltotal = 0; // initialize total

// total even integers from 2 through 20// total even integers from 2 through 20// total even integers from 2 through 20// total even integers from 2 through 20

for ( for ( for ( for ( intintintint number = 2; number <= 20; number += 2 )number = 2; number <= 20; number += 2 )number = 2; number <= 20; number += 2 )number = 2; number <= 20; number += 2 )

total += number;total += number;total += number;total += number;

System.out.printfSystem.out.printfSystem.out.printfSystem.out.printf( "Sum is %( "Sum is %( "Sum is %( "Sum is %dddd\\\\nnnn", total ); // display results", total ); // display results", total ); // display results", total ); // display results

} // end main} // end main} // end main} // end main

} // end class Sum} // end class Sum} // end class Sum} // end class Sum

Sum is 110Sum is 110Sum is 110Sum is 110

11

Compound Interest Calculation

• A person invest $1.000 in a savings account yielding 5% interest. Assuming that all the interest is left on deposit, calculate and print the amount of money in the account at the end of each year for 10 years. Use the following formula to determine the amount:a = p(1 + r)n

where– p is the original amount invested

– r is annual interest rate

– n is number of years

– a is amount on deposit at the end of the nth year

Outline12

// Compound// Compound// Compound// Compound----interest calculations with for.interest calculations with for.interest calculations with for.interest calculations with for.

public class Interest public class Interest public class Interest public class Interest

{{{{


{{{{

double amount; // amount on deposit at end of each yeardouble amount; // amount on deposit at end of each yeardouble amount; // amount on deposit at end of each yeardouble amount; // amount on deposit at end of each year

double principal = 1000.0; // initial amount before interedouble principal = 1000.0; // initial amount before interedouble principal = 1000.0; // initial amount before interedouble principal = 1000.0; // initial amount before interestststst

double rate = 0.05; // interest ratedouble rate = 0.05; // interest ratedouble rate = 0.05; // interest ratedouble rate = 0.05; // interest rate

// display headers// display headers// display headers// display headers

System.out.printfSystem.out.printfSystem.out.printfSystem.out.printf( "%s%20s( "%s%20s( "%s%20s( "%s%20s\\\\n", "Year", "Amount on deposit" );n", "Year", "Amount on deposit" );n", "Year", "Amount on deposit" );n", "Year", "Amount on deposit" );

// calculate amount on deposit for each of ten years// calculate amount on deposit for each of ten years// calculate amount on deposit for each of ten years// calculate amount on deposit for each of ten years

for ( for ( for ( for ( intintintint year = 1; year <= 10; year++ ) year = 1; year <= 10; year++ ) year = 1; year <= 10; year++ ) year = 1; year <= 10; year++ )

{{{{

// calculate new amount for specified year// calculate new amount for specified year// calculate new amount for specified year// calculate new amount for specified year

amount = principal * amount = principal * amount = principal * amount = principal * Math.powMath.powMath.powMath.pow( 1.0 + rate, year );( 1.0 + rate, year );( 1.0 + rate, year );( 1.0 + rate, year );

// display the year and the amount// display the year and the amount// display the year and the amount// display the year and the amount

System.out.printfSystem.out.printfSystem.out.printfSystem.out.printf( "%4d%,20.2f( "%4d%,20.2f( "%4d%,20.2f( "%4d%,20.2f\\\\n", year, amount );n", year, amount );n", year, amount );n", year, amount );

} // end for} // end for} // end for} // end for


} // end class Interest} // end class Interest} // end class Interest} // end class Interest

Outline13

Year Amount on depositYear Amount on depositYear Amount on depositYear Amount on deposit

1 1,050.001 1,050.001 1,050.001 1,050.00

2 1,102.502 1,102.502 1,102.502 1,102.50

3 1,157.633 1,157.633 1,157.633 1,157.63

4 1,215.514 1,215.514 1,215.514 1,215.51

5 1,276.285 1,276.285 1,276.285 1,276.28

6 1,340.106 1,340.106 1,340.106 1,340.10

7 1,407.107 1,407.107 1,407.107 1,407.10

8 1,477.468 1,477.468 1,477.468 1,477.46

9 1,551.339 1,551.339 1,551.339 1,551.33

10 1,628.8910 1,628.8910 1,628.8910 1,628.89

14

4.12 do…while Repetition Statement

• do…while structure– Similar to while structure

– Tests loop-continuation after performing body of loop• i.e., loop body always executes at least once

Outline15

// do...// do...// do...// do...whilewhilewhilewhile repetitionrepetitionrepetitionrepetition statementstatementstatementstatement....

public public public public classclassclassclass DoWhileTestDoWhileTestDoWhileTestDoWhileTest

{ { { {

public static public static public static public static voidvoidvoidvoid mainmainmainmain( ( ( ( StringStringStringString argsargsargsargs[] )[] )[] )[] )

{{{{

intintintint countercountercountercounter = 1; // = 1; // = 1; // = 1; // initializeinitializeinitializeinitialize countercountercountercounter

do do do do

{{{{


++++++++countercountercountercounter;;;;

} } } } whilewhilewhilewhile ( ( ( ( countercountercountercounter <= 10 ); // <= 10 ); // <= 10 ); // <= 10 ); // endendendend do...do...do...do...whilewhilewhilewhile

SystemSystemSystemSystem....outoutoutout....printlnprintlnprintlnprintln(); // (); // (); // (); // outputsoutputsoutputsoutputs a a a a newlinenewlinenewlinenewline


} // } // } // } // endendendend classclassclassclass DoWhileTestDoWhileTestDoWhileTestDoWhileTest

1 2 3 4 5 6 7 8 9 101 2 3 4 5 6 7 8 9 101 2 3 4 5 6 7 8 9 101 2 3 4 5 6 7 8 9 10

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Fig. 4.8 do…while repetition statement activity diagram.

action state

[true]

[false]

condition

17

4.13 switch Multiple-Selection Statement

• switch statement– Used for multiple selections

Outline18

// // // // GradeBookGradeBookGradeBookGradeBook class uses switch statement to count A, B, C, D and F grades.class uses switch statement to count A, B, C, D and F grades.class uses switch statement to count A, B, C, D and F grades.class uses switch statement to count A, B, C, D and F grades.

import import import import java.util.Scannerjava.util.Scannerjava.util.Scannerjava.util.Scanner; // program uses class Scanner; // program uses class Scanner; // program uses class Scanner; // program uses class Scanner

public class public class public class public class GradeBookGradeBookGradeBookGradeBook

{{{{

private String private String private String private String courseNamecourseNamecourseNamecourseName; // name of course this ; // name of course this ; // name of course this ; // name of course this GradeBookGradeBookGradeBookGradeBook representsrepresentsrepresentsrepresents

private private private private intintintint total; // sum of gradestotal; // sum of gradestotal; // sum of gradestotal; // sum of grades

private private private private intintintint gradeCountergradeCountergradeCountergradeCounter; // number of grades entered; // number of grades entered; // number of grades entered; // number of grades entered

private private private private intintintint aCountaCountaCountaCount; // count of A grades; // count of A grades; // count of A grades; // count of A grades

private private private private intintintint bCountbCountbCountbCount; // count of B grades; // count of B grades; // count of B grades; // count of B grades

private private private private intintintint cCountcCountcCountcCount; // count of C grades; // count of C grades; // count of C grades; // count of C grades

private private private private intintintint dCountdCountdCountdCount; // count of D grades; // count of D grades; // count of D grades; // count of D grades

private private private private intintintint fCountfCountfCountfCount; // count of F grades; // count of F grades; // count of F grades; // count of F grades

// constructor initializes // constructor initializes // constructor initializes // constructor initializes courseNamecourseNamecourseNamecourseName; ; ; ;

// // // // intintintint instance variables are initialized to 0 by defaultinstance variables are initialized to 0 by defaultinstance variables are initialized to 0 by defaultinstance variables are initialized to 0 by default

public public public public GradeBookGradeBookGradeBookGradeBook( String name )( String name )( String name )( String name )

{{{{

courseNamecourseNamecourseNamecourseName = name; // initializes = name; // initializes = name; // initializes = name; // initializes courseNamecourseNamecourseNamecourseName

} // end constructor} // end constructor} // end constructor} // end constructor

// method to set the course name// method to set the course name// method to set the course name// method to set the course name

public void public void public void public void setCourseNamesetCourseNamesetCourseNamesetCourseName( String name )( String name )( String name )( String name )

{{{{

courseNamecourseNamecourseNamecourseName = name; // store the course name= name; // store the course name= name; // store the course name= name; // store the course name

} // end method } // end method } // end method } // end method setCourseNamesetCourseNamesetCourseNamesetCourseName

Outline19

// // // // methodmethodmethodmethod to to to to retrieveretrieveretrieveretrieve thethethethe coursecoursecoursecourse namenamenamename

public public public public StringStringStringString getCourseNamegetCourseNamegetCourseNamegetCourseName()()()()

{{{{

returnreturnreturnreturn courseNamecourseNamecourseNamecourseName;;;;

} // } // } // } // endendendend methodmethodmethodmethod getCourseNamegetCourseNamegetCourseNamegetCourseName

// display a // display a // display a // display a welcomewelcomewelcomewelcome messagemessagemessagemessage to to to to thethethethe GradeBookGradeBookGradeBookGradeBook useruseruseruser

public public public public voidvoidvoidvoid displayMessagedisplayMessagedisplayMessagedisplayMessage()()()()

{{{{

// // // // getCourseNamegetCourseNamegetCourseNamegetCourseName getsgetsgetsgets thethethethe namenamenamename ofofofof thethethethe coursecoursecoursecourse

SystemSystemSystemSystem....outoutoutout....printfprintfprintfprintf( "( "( "( "WelcomeWelcomeWelcomeWelcome to to to to thethethethe grade grade grade grade bookbookbookbook forforforfor\\\\n%s!n%s!n%s!n%s!\\\\nnnn\\\\n", n", n", n",

getCourseNamegetCourseNamegetCourseNamegetCourseName() );() );() );() );

} // } // } // } // endendendend methodmethodmethodmethod displayMessagedisplayMessagedisplayMessagedisplayMessage

// // // // inputinputinputinput arbitraryarbitraryarbitraryarbitrary numbernumbernumbernumber ofofofof gradesgradesgradesgrades fromfromfromfrom useruseruseruser

public public public public voidvoidvoidvoid inputGradesinputGradesinputGradesinputGrades()()()()

{{{{

Scanner Scanner Scanner Scanner inputinputinputinput = = = = newnewnewnew Scanner( Scanner( Scanner( Scanner( SystemSystemSystemSystem.in );.in );.in );.in );

intintintint grade; // grade grade; // grade grade; // grade grade; // grade enteredenteredenteredentered by by by by useruseruseruser

SystemSystemSystemSystem....outoutoutout....printfprintfprintfprintf( "%s( "%s( "%s( "%s\\\\n%sn%sn%sn%s\\\\n %sn %sn %sn %s\\\\n %sn %sn %sn %s\\\\n", n", n", n",

""""EnterEnterEnterEnter thethethethe integerintegerintegerinteger gradesgradesgradesgrades in in in in thethethethe rangerangerangerange 0000----100.", 100.", 100.", 100.",

"Type "Type "Type "Type thethethethe endendendend----ofofofof----filefilefilefile indicatorindicatorindicatorindicator to to to to terminateterminateterminateterminate inputinputinputinput:", :", :", :",

"On UNIX/Linux/Mac OS X type <"On UNIX/Linux/Mac OS X type <"On UNIX/Linux/Mac OS X type <"On UNIX/Linux/Mac OS X type <ctrlctrlctrlctrl> d > d > d > d thenthenthenthen presspresspresspress EnterEnterEnterEnter",",",",

"On Windows type <"On Windows type <"On Windows type <"On Windows type <ctrlctrlctrlctrl> z > z > z > z thenthenthenthen presspresspresspress EnterEnterEnterEnter" );" );" );" );

Outline20

// loop until user enters the end// loop until user enters the end// loop until user enters the end// loop until user enters the end----ofofofof----file indicatorfile indicatorfile indicatorfile indicator

while ( while ( while ( while ( input.hasNextinput.hasNextinput.hasNextinput.hasNext() ) () ) () ) () )

{{{{

grade = grade = grade = grade = input.nextIntinput.nextIntinput.nextIntinput.nextInt(); // read grade(); // read grade(); // read grade(); // read grade

total += grade; // add grade to totaltotal += grade; // add grade to totaltotal += grade; // add grade to totaltotal += grade; // add grade to total

++++++++gradeCountergradeCountergradeCountergradeCounter; // increment number of grades; // increment number of grades; // increment number of grades; // increment number of grades

// call method to increment appropriate counter// call method to increment appropriate counter// call method to increment appropriate counter// call method to increment appropriate counter

incrementLetterGradeCounterincrementLetterGradeCounterincrementLetterGradeCounterincrementLetterGradeCounter( grade );( grade );( grade );( grade );

} // end while } // end while } // end while } // end while

} // end method } // end method } // end method } // end method inputGradesinputGradesinputGradesinputGrades

// add 1 to appropriate counter for specified grade// add 1 to appropriate counter for specified grade// add 1 to appropriate counter for specified grade// add 1 to appropriate counter for specified grade

public void public void public void public void incrementLetterGradeCounterincrementLetterGradeCounterincrementLetterGradeCounterincrementLetterGradeCounter( ( ( ( intintintint grade )grade )grade )grade )

{{{{

// determine which grade was entered// determine which grade was entered// determine which grade was entered// determine which grade was entered

switch ( grade / 10 )switch ( grade / 10 )switch ( grade / 10 )switch ( grade / 10 )

{ { { {

case 9: // grade was between 90case 9: // grade was between 90case 9: // grade was between 90case 9: // grade was between 90

case 10: // and 100 case 10: // and 100 case 10: // and 100 case 10: // and 100

++++++++aCountaCountaCountaCount; // increment ; // increment ; // increment ; // increment aCountaCountaCountaCount

break; // necessary to exit switchbreak; // necessary to exit switchbreak; // necessary to exit switchbreak; // necessary to exit switch

case 8: // grade was between 80 and 89case 8: // grade was between 80 and 89case 8: // grade was between 80 and 89case 8: // grade was between 80 and 89

++++++++bCountbCountbCountbCount; // increment ; // increment ; // increment ; // increment bCountbCountbCountbCount

break; // exit switchbreak; // exit switchbreak; // exit switchbreak; // exit switch

Outline21

casecasecasecase 7: // grade 7: // grade 7: // grade 7: // grade waswaswaswas betweenbetweenbetweenbetween 70 70 70 70 andandandand 79797979

++++++++cCountcCountcCountcCount; // ; // ; // ; // incrementincrementincrementincrement cCountcCountcCountcCount

breakbreakbreakbreak; // exit ; // exit ; // exit ; // exit switchswitchswitchswitch

casecasecasecase 6: // grade 6: // grade 6: // grade 6: // grade waswaswaswas betweenbetweenbetweenbetween 60 60 60 60 andandandand 69696969

++++++++dCountdCountdCountdCount; // ; // ; // ; // incrementincrementincrementincrement dCountdCountdCountdCount

breakbreakbreakbreak; // exit ; // exit ; // exit ; // exit switchswitchswitchswitch

default: // grade default: // grade default: // grade default: // grade waswaswaswas lesslesslessless thanthanthanthan 60606060

++++++++fCountfCountfCountfCount; // ; // ; // ; // incrementincrementincrementincrement fCountfCountfCountfCount

breakbreakbreakbreak; // ; // ; // ; // optionaloptionaloptionaloptional; ; ; ; willwillwillwill exit exit exit exit switchswitchswitchswitch anywayanywayanywayanyway

} // } // } // } // endendendend switchswitchswitchswitch

} // } // } // } // endendendend methodmethodmethodmethod incrementLetterGradeCounterincrementLetterGradeCounterincrementLetterGradeCounterincrementLetterGradeCounter

// display a report // display a report // display a report // display a report basedbasedbasedbased on on on on thethethethe gradesgradesgradesgrades enteredenteredenteredentered by by by by useruseruseruser

public public public public voidvoidvoidvoid displayGradeReportdisplayGradeReportdisplayGradeReportdisplayGradeReport()()()()

{{{{

SystemSystemSystemSystem....outoutoutout....printlnprintlnprintlnprintln( "( "( "( "\\\\nGradenGradenGradenGrade Report:" );Report:" );Report:" );Report:" );

Outline22

// if user entered at least one grade...// if user entered at least one grade...// if user entered at least one grade...// if user entered at least one grade...

if ( if ( if ( if ( gradeCountergradeCountergradeCountergradeCounter != 0 ) != 0 ) != 0 ) != 0 )

{{{{

// calculate average of all grades entered// calculate average of all grades entered// calculate average of all grades entered// calculate average of all grades entered

double average = (double) total / double average = (double) total / double average = (double) total / double average = (double) total / gradeCountergradeCountergradeCountergradeCounter; ; ; ;

// output summary of results// output summary of results// output summary of results// output summary of results

System.out.printfSystem.out.printfSystem.out.printfSystem.out.printf( "Total of the %d grades entered is %( "Total of the %d grades entered is %( "Total of the %d grades entered is %( "Total of the %d grades entered is %dddd\\\\nnnn", ", ", ",

gradeCountergradeCountergradeCountergradeCounter, total );, total );, total );, total );

System.out.printfSystem.out.printfSystem.out.printfSystem.out.printf( "Class average is %.2f( "Class average is %.2f( "Class average is %.2f( "Class average is %.2f\\\\n", average );n", average );n", average );n", average );

System.out.printfSystem.out.printfSystem.out.printfSystem.out.printf( "%( "%( "%( "%ssss\\\\n%s%dn%s%dn%s%dn%s%d\\\\n%s%dn%s%dn%s%dn%s%d\\\\n%s%dn%s%dn%s%dn%s%d\\\\n%s%dn%s%dn%s%dn%s%d\\\\n%s%dn%s%dn%s%dn%s%d\\\\nnnn", ", ", ",

"Number of students who received each grade:", "Number of students who received each grade:", "Number of students who received each grade:", "Number of students who received each grade:",

"A: ", "A: ", "A: ", "A: ", aCountaCountaCountaCount, // display number of A grades, // display number of A grades, // display number of A grades, // display number of A grades

"B: ", "B: ", "B: ", "B: ", bCountbCountbCountbCount, // display number of B grades, // display number of B grades, // display number of B grades, // display number of B grades

"C: ", "C: ", "C: ", "C: ", cCountcCountcCountcCount, // display number of C grades , // display number of C grades , // display number of C grades , // display number of C grades

"D: ", "D: ", "D: ", "D: ", dCountdCountdCountdCount, // display number of D grades, // display number of D grades, // display number of D grades, // display number of D grades

"F: ", "F: ", "F: ", "F: ", fCountfCountfCountfCount ); // display number of F grades); // display number of F grades); // display number of F grades); // display number of F grades

} // end if} // end if} // end if} // end if

else // no grades were entered, so output appropriate messelse // no grades were entered, so output appropriate messelse // no grades were entered, so output appropriate messelse // no grades were entered, so output appropriate messageageageage

System.out.printlnSystem.out.printlnSystem.out.printlnSystem.out.println( "No grades were entered" );( "No grades were entered" );( "No grades were entered" );( "No grades were entered" );

} // end method } // end method } // end method } // end method displayGradeReportdisplayGradeReportdisplayGradeReportdisplayGradeReport

} // end class } // end class } // end class } // end class GradeBookGradeBookGradeBookGradeBook

Outline23

// // // // CreateCreateCreateCreate GradeBookGradeBookGradeBookGradeBook objectobjectobjectobject, , , , inputinputinputinput gradesgradesgradesgrades andandandand display grade report.display grade report.display grade report.display grade report.

public public public public classclassclassclass GradeBookTestGradeBookTestGradeBookTestGradeBookTest

{{{{


{{{{

// // // // createcreatecreatecreate GradeBookGradeBookGradeBookGradeBook objectobjectobjectobject myGradeBookmyGradeBookmyGradeBookmyGradeBook andandandand

// // // // passpasspasspass coursecoursecoursecourse namenamenamename to to to to constructorconstructorconstructorconstructor

GradeBookGradeBookGradeBookGradeBook myGradeBookmyGradeBookmyGradeBookmyGradeBook = = = = newnewnewnew GradeBookGradeBookGradeBookGradeBook( ( ( (

"CS101 "CS101 "CS101 "CS101 IntroductionIntroductionIntroductionIntroduction to Java to Java to Java to Java ProgrammingProgrammingProgrammingProgramming" );" );" );" );

myGradeBookmyGradeBookmyGradeBookmyGradeBook....displayMessagedisplayMessagedisplayMessagedisplayMessage(); // display (); // display (); // display (); // display welcomewelcomewelcomewelcome messagemessagemessagemessage

myGradeBookmyGradeBookmyGradeBookmyGradeBook....inputGradesinputGradesinputGradesinputGrades(); // (); // (); // (); // readreadreadread gradesgradesgradesgrades fromfromfromfrom useruseruseruser

myGradeBookmyGradeBookmyGradeBookmyGradeBook....displayGradeReportdisplayGradeReportdisplayGradeReportdisplayGradeReport(); // display report (); // display report (); // display report (); // display report basedbasedbasedbased on on on on gradesgradesgradesgrades


} // } // } // } // endendendend classclassclassclass GradeBookTestGradeBookTestGradeBookTestGradeBookTest

Outline24

Welcome to the grade book forWelcome to the grade book forWelcome to the grade book forWelcome to the grade book for

CS101 Introduction to Java Programming!CS101 Introduction to Java Programming!CS101 Introduction to Java Programming!CS101 Introduction to Java Programming!

Enter the integer grades in the range 0Enter the integer grades in the range 0Enter the integer grades in the range 0Enter the integer grades in the range 0----100.100.100.100.

Type the endType the endType the endType the end----ofofofof----file indicator to terminate input:file indicator to terminate input:file indicator to terminate input:file indicator to terminate input:

On UNIX/Linux/Mac OS X type <ctrl> d then press On UNIX/Linux/Mac OS X type <ctrl> d then press On UNIX/Linux/Mac OS X type <ctrl> d then press On UNIX/Linux/Mac OS X type <ctrl> d then press EnteEnteEnteEnte

On Windows type <ctrl> z then press EnterOn Windows type <ctrl> z then press EnterOn Windows type <ctrl> z then press EnterOn Windows type <ctrl> z then press Enter

99999999

92929292

45454545

57575757

63636363

71717171

76767676

85858585

90909090

100100100100

^Z^Z^Z^Z

Grade Report:Grade Report:Grade Report:Grade Report:

Total of the 10 grades entered is 778Total of the 10 grades entered is 778Total of the 10 grades entered is 778Total of the 10 grades entered is 778

Class average is 77,80Class average is 77,80Class average is 77,80Class average is 77,80

Number of students who received each grade:Number of students who received each grade:Number of students who received each grade:Number of students who received each grade:

A: 4A: 4A: 4A: 4

B: 1B: 1B: 1B: 1

C: 2C: 2C: 2C: 2

D: 1D: 1D: 1D: 1

F: 2F: 2F: 2F: 2

25

Fig. 4.10 switch multiple-selection statement activity diagram with break statements.

case a action(s) break

default action(s)

[true]

case b action(s) break

case z action(s) break

.

.

.

[false]

case a

[true]

[true]

case b

case z

[false]

[false]

26

4.14 break and continue Statements

• break/continue– Alter flow of control

• break statement – Causes immediate exit from control structure

• Used in while, for, do…while or switch statements

• continue statement – Skips remaining statements in loop body

– Proceeds to next iteration• Used in while, for or do…while statements

Outline27

// break statement exiting a for statement.// break statement exiting a for statement.// break statement exiting a for statement.// break statement exiting a for statement.

public class public class public class public class BreakTestBreakTestBreakTestBreakTest

{{{{


{{{{

intintintint count; // control variable also used after loop terminatescount; // control variable also used after loop terminatescount; // control variable also used after loop terminatescount; // control variable also used after loop terminates

for ( count = 1; count <= 10; count++ ) // loop 10 timesfor ( count = 1; count <= 10; count++ ) // loop 10 timesfor ( count = 1; count <= 10; count++ ) // loop 10 timesfor ( count = 1; count <= 10; count++ ) // loop 10 times

{ { { {

if ( count == 5 ) // if count is 5, if ( count == 5 ) // if count is 5, if ( count == 5 ) // if count is 5, if ( count == 5 ) // if count is 5,

break; // terminate loopbreak; // terminate loopbreak; // terminate loopbreak; // terminate loop

System.out.printfSystem.out.printfSystem.out.printfSystem.out.printf( "%d ", count );( "%d ", count );( "%d ", count );( "%d ", count );


System.out.printfSystem.out.printfSystem.out.printfSystem.out.printf( "( "( "( "\\\\nBrokenBrokenBrokenBroke out of loop at count = %out of loop at count = %out of loop at count = %out of loop at count = %dddd\\\\nnnn", count );", count );", count );", count );


} // end class } // end class } // end class } // end class BreakTestBreakTestBreakTestBreakTest

1 2 3 41 2 3 41 2 3 41 2 3 4

Broke out of loop at count = 5Broke out of loop at count = 5Broke out of loop at count = 5Broke out of loop at count = 5

Outline28

// continue statement terminating an iteration of a for statemen// continue statement terminating an iteration of a for statemen// continue statement terminating an iteration of a for statemen// continue statement terminating an iteration of a for statement.t.t.t.

public class public class public class public class ContinueTestContinueTestContinueTestContinueTest

{{{{


{{{{

for ( for ( for ( for ( intintintint count = 1; count <= 10; count++ ) // loop 10 timescount = 1; count <= 10; count++ ) // loop 10 timescount = 1; count <= 10; count++ ) // loop 10 timescount = 1; count <= 10; count++ ) // loop 10 times

{ { { {

if ( count == 5 ) // if count is 5, if ( count == 5 ) // if count is 5, if ( count == 5 ) // if count is 5, if ( count == 5 ) // if count is 5,

continue; // skip remaining code in loopcontinue; // skip remaining code in loopcontinue; // skip remaining code in loopcontinue; // skip remaining code in loop

System.out.printfSystem.out.printfSystem.out.printfSystem.out.printf( "%d ", count );( "%d ", count );( "%d ", count );( "%d ", count );


System.out.printlnSystem.out.printlnSystem.out.printlnSystem.out.println( "( "( "( "\\\\nUsednUsednUsednUsed continue to skip printing 5" );continue to skip printing 5" );continue to skip printing 5" );continue to skip printing 5" );


} // end class } // end class } // end class } // end class ContinueTestContinueTestContinueTestContinueTest

1 2 3 41 2 3 41 2 3 41 2 3 4

Broke out of loop at count = 5Broke out of loop at count = 5Broke out of loop at count = 5Broke out of loop at count = 5

29

4.15 Logical Operators

• Logical operators– Allows for forming more complex conditions

– Combines simple conditions

• Java logical operators– && (conditional AND)

– & (boolean logical AND)

– || (conditional OR)

– | (boolean logical inclusive OR)

– ^ (boolean logical exclusive OR)

– ! (logical NOT)

30

4.15 Logical Operators

• if (gender == FEMALE && age >= 65 )++seniorFemales;

• possible notation:if ((gender == FEMALE ) && ( age>= 65))

++seniorFemales;

• short-circuit evaluation of complex condition (not all parts of condition are evaluated each time; first part of condition is evaluated each time and the result may be known

• & and | evaluated each time both parts of the condition

31

expression1 expression2 expression1 &&&&&&&& expression2

false false false

false true false true false false true true true Fig. 4.15 &&&&&&&& (conditional AND) operator truth table.

expression1 expression2 expression1 ||||||||expression2

false false false

false true truetrue false true

true true trueFig. 4.16 |||||||| (conditional OR) operator truth table.

32

expression1 expression2 expression1 ^̂̂̂ expression2

false false false

false true true true false true true true false Fig. 4.17 ^̂̂̂ (boolean logical exclusive OR) operator truth table.

expression !!!!expressionfalse true

true falseFig. 4.18 !!!! (logical negation, or logical NOT) operator truth table.

Outline33

// // // // LogicalLogicalLogicalLogical operatorsoperatorsoperatorsoperators....

public public public public classclassclassclass LogicalOperatorsLogicalOperatorsLogicalOperatorsLogicalOperators

{{{{


{{{{

// // // // createcreatecreatecreate truthtruthtruthtruth table table table table forforforfor && (&& (&& (&& (conditionalconditionalconditionalconditional AND) AND) AND) AND) operatoroperatoroperatoroperator

SystemSystemSystemSystem....outoutoutout....printfprintfprintfprintf( "%s( "%s( "%s( "%s\\\\n%s: %bn%s: %bn%s: %bn%s: %b\\\\n%s: %bn%s: %bn%s: %bn%s: %b\\\\n%s: %bn%s: %bn%s: %bn%s: %b\\\\n%s: %bn%s: %bn%s: %bn%s: %b\\\\nnnn\\\\n",n",n",n",

""""ConditionalConditionalConditionalConditional AND (&&)", "AND (&&)", "AND (&&)", "AND (&&)", "falsefalsefalsefalse && && && && falsefalsefalsefalse", ( ", ( ", ( ", ( falsefalsefalsefalse && && && && falsefalsefalsefalse ),),),),

""""falsefalsefalsefalse && && && && truetruetruetrue", ( ", ( ", ( ", ( falsefalsefalsefalse && && && && truetruetruetrue ), ), ), ),

""""truetruetruetrue && && && && falsefalsefalsefalse", ( ", ( ", ( ", ( truetruetruetrue && && && && falsefalsefalsefalse ),),),),

""""truetruetruetrue && && && && truetruetruetrue", ( ", ( ", ( ", ( truetruetruetrue && && && && truetruetruetrue ) );) );) );) );

// // // // createcreatecreatecreate truthtruthtruthtruth table table table table forforforfor || (|| (|| (|| (conditionalconditionalconditionalconditional OR) OR) OR) OR) operatoroperatoroperatoroperator


""""ConditionalConditionalConditionalConditional OR (||)", "OR (||)", "OR (||)", "OR (||)", "falsefalsefalsefalse || || || || falsefalsefalsefalse", ( ", ( ", ( ", ( falsefalsefalsefalse || || || || falsefalsefalsefalse ),),),),

""""falsefalsefalsefalse || || || || truetruetruetrue", ( ", ( ", ( ", ( falsefalsefalsefalse || || || || truetruetruetrue ),),),),

""""truetruetruetrue || || || || falsefalsefalsefalse", ( ", ( ", ( ", ( truetruetruetrue || || || || falsefalsefalsefalse ),),),),

""""truetruetruetrue || || || || truetruetruetrue", ( ", ( ", ( ", ( truetruetruetrue || || || || truetruetruetrue ) );) );) );) );

// // // // createcreatecreatecreate truthtruthtruthtruth table table table table forforforfor & (& (& (& (booleanbooleanbooleanboolean logicallogicallogicallogical AND) AND) AND) AND) operatoroperatoroperatoroperator


""""BooleanBooleanBooleanBoolean logicallogicallogicallogical AND (&)", "AND (&)", "AND (&)", "AND (&)", "falsefalsefalsefalse & & & & falsefalsefalsefalse", ( ", ( ", ( ", ( falsefalsefalsefalse & & & & falsefalsefalsefalse ),),),),

""""falsefalsefalsefalse & & & & truetruetruetrue", ( ", ( ", ( ", ( falsefalsefalsefalse & & & & truetruetruetrue ),),),),

""""truetruetruetrue & & & & falsefalsefalsefalse", ( ", ( ", ( ", ( truetruetruetrue & & & & falsefalsefalsefalse ),),),),

""""truetruetruetrue & & & & truetruetruetrue", ( ", ( ", ( ", ( truetruetruetrue & & & & truetruetruetrue ) );) );) );) );

Outline34

// // // // createcreatecreatecreate truthtruthtruthtruth table table table table forforforfor | (| (| (| (booleanbooleanbooleanboolean logicallogicallogicallogical inclusiveinclusiveinclusiveinclusive OR) OR) OR) OR) operatoroperatoroperatoroperator


""""BooleanBooleanBooleanBoolean logicallogicallogicallogical inclusiveinclusiveinclusiveinclusive OR (|)",OR (|)",OR (|)",OR (|)",

""""falsefalsefalsefalse | | | | falsefalsefalsefalse", ( ", ( ", ( ", ( falsefalsefalsefalse | | | | falsefalsefalsefalse ),),),),

""""falsefalsefalsefalse | | | | truetruetruetrue", ( ", ( ", ( ", ( falsefalsefalsefalse | | | | truetruetruetrue ),),),),

""""truetruetruetrue | | | | falsefalsefalsefalse", ( ", ( ", ( ", ( truetruetruetrue | | | | falsefalsefalsefalse ),),),),

""""truetruetruetrue | | | | truetruetruetrue", ( ", ( ", ( ", ( truetruetruetrue | | | | truetruetruetrue ) );) );) );) );

// // // // createcreatecreatecreate truthtruthtruthtruth table table table table forforforfor ^ (^ (^ (^ (booleanbooleanbooleanboolean logicallogicallogicallogical exclusiveexclusiveexclusiveexclusive OR) OR) OR) OR) operatoroperatoroperatoroperator


""""BooleanBooleanBooleanBoolean logicallogicallogicallogical exclusiveexclusiveexclusiveexclusive OR (^)", OR (^)", OR (^)", OR (^)",

""""falsefalsefalsefalse ^ ^ ^ ^ falsefalsefalsefalse", ( ", ( ", ( ", ( falsefalsefalsefalse ^ ^ ^ ^ falsefalsefalsefalse ),),),),

""""falsefalsefalsefalse ^ ^ ^ ^ truetruetruetrue", ( ", ( ", ( ", ( falsefalsefalsefalse ^ ^ ^ ^ truetruetruetrue ),),),),

""""truetruetruetrue ^ ^ ^ ^ falsefalsefalsefalse", ( ", ( ", ( ", ( truetruetruetrue ^ ^ ^ ^ falsefalsefalsefalse ),),),),

""""truetruetruetrue ^ ^ ^ ^ truetruetruetrue", ( ", ( ", ( ", ( truetruetruetrue ^ ^ ^ ^ truetruetruetrue ) );) );) );) );

// // // // createcreatecreatecreate truthtruthtruthtruth table table table table forforforfor ! (! (! (! (logicallogicallogicallogical negationnegationnegationnegation) ) ) ) operatoroperatoroperatoroperator

SystemSystemSystemSystem....outoutoutout....printfprintfprintfprintf( "%s( "%s( "%s( "%s\\\\n%s: %bn%s: %bn%s: %bn%s: %b\\\\n%s: %bn%s: %bn%s: %bn%s: %b\\\\n", "n", "n", "n", "LogicalLogicalLogicalLogical NOT (!)",NOT (!)",NOT (!)",NOT (!)",

"!"!"!"!falsefalsefalsefalse", ( !", ( !", ( !", ( !falsefalsefalsefalse ), "!), "!), "!), "!truetruetruetrue", ( !", ( !", ( !", ( !truetruetruetrue ) );) );) );) );


} // } // } // } // endendendend classclassclassclass LogicalOperatorsLogicalOperatorsLogicalOperatorsLogicalOperators

Outline35

Conditional AND (&&)Conditional AND (&&)Conditional AND (&&)Conditional AND (&&)

false && false: falsefalse && false: falsefalse && false: falsefalse && false: false

false && true: falsefalse && true: falsefalse && true: falsefalse && true: false

true && false: falsetrue && false: falsetrue && false: falsetrue && false: false

true && true: truetrue && true: truetrue && true: truetrue && true: true

Conditional OR (||)Conditional OR (||)Conditional OR (||)Conditional OR (||)

false || false: falsefalse || false: falsefalse || false: falsefalse || false: false

false || true: truefalse || true: truefalse || true: truefalse || true: true

true || false: truetrue || false: truetrue || false: truetrue || false: true

true || true: truetrue || true: truetrue || true: truetrue || true: true

Boolean logical AND (&)Boolean logical AND (&)Boolean logical AND (&)Boolean logical AND (&)

false & false: falsefalse & false: falsefalse & false: falsefalse & false: false

false & true: falsefalse & true: falsefalse & true: falsefalse & true: false

true & false: falsetrue & false: falsetrue & false: falsetrue & false: false

t rue & true: truet rue & true: truet rue & true: truet rue & true: true

Boolean logical inclusive OR (|)Boolean logical inclusive OR (|)Boolean logical inclusive OR (|)Boolean logical inclusive OR (|)

false | false: falsefalse | false: falsefalse | false: falsefalse | false: false

false | true: truefalse | true: truefalse | true: truefalse | true: true

true | false: truetrue | false: truetrue | false: truetrue | false: true

true | true: truetrue | true: truetrue | true: truetrue | true: true

Outline36

Boolean logical exclusive OR (^)Boolean logical exclusive OR (^)Boolean logical exclusive OR (^)Boolean logical exclusive OR (^)

false ^ false: falsefalse ^ false: falsefalse ^ false: falsefalse ^ false: false

false ^ true: truefalse ^ true: truefalse ^ true: truefalse ^ true: true

true ^ false: truetrue ^ false: truetrue ^ false: truetrue ^ false: true

true ^ true: falsetrue ^ true: falsetrue ^ true: falsetrue ^ true: false

Logical NOT (!)Logical NOT (!)Logical NOT (!)Logical NOT (!)

!false: true!false: true!false: true!false: true

!true: false!true: false!true: false!true: false

37

4.16 Structured Programming Summary

• Sequence structure– “built-in” to Java

• Selection structure– if, if…else and switch

• Repetition structure– while, do…while and for

38

Fig. 4.21 Java’s single-entry/single-exit sequence, selection and repetition statements.

[t]

[f]

[f]

[t]

break

break

[t]break

[t]

[f][t]

[f]

[t]

[f]

[t]

[f]

Repetition

while statement do while statement for statement

SelectionSequence

if else statement (double selection)

if statement (single selection)

switch statement (multiple selection)

.

.

.

[t][f]

default

39

Rules for Forming Structured Programs 1) Begin with the “simplest activity diagram” (Fig. 5.23). 2) Any action state can be replaced by two action states in sequence. 3) Any action state can be replaced by any control statement (sequence,

if, if else, switch, while, do while or for). 4) Rules 2 and 3 can be applied as often as you like and in any order. Fig. 4.22 Rules for forming structured programs.

action state

Fig. 4.23 Simplest activity diagram.

40

Fig. 4.24 Repeatedly applying rule 2 of Fig. 4.22 to the simplest activity diagram.

.

.

.action state

action state

apply Rule 2

apply Rule 2

apply Rule 2

action state

action state

action state

action state

action state

action state

41

Fig. 4.25 Applying rule 3 of Fig. 4.22 to the simple st activity diagram.

action state

apply Rule 3

apply Rule 3

apply Rule 3 action stateaction state

action stateaction state action stateaction state

[f] [t]

[f] [t]

[f] [t][f] [t]

42

Fig. 4.26 Activity diagram with illegal syntax.

action state

action state

action state

action state

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