Java TASession 1

Software

• Java Runtime Environment (JRE)• java.exe

• Java Development Kit (JDK)• java.exe, javac.exe• Version 1.6 = Version 6, Version 1.7 = Version 7• Edit System Variables:• JAVA_HOME=C:\Program Files\Java\jdk1.6.0_32• PATH=[…];C:\Program Files\Java\jdk1.6.0_32\bin

• Editor: Notepad++, gedit

Java Startup

• Open Test.java

• Run javac:• C:\Users\user\Documents>javac Test.java

• Run java:• C:\Users\user\Documents>java Test• Salam

class Test {public static void main(String[] args) {

System.out.println("Salam");}

}

ErrorsC:\Users\user\Documents>javac Add1.javaAdd1.java:3: cannot find symbolsymbol : class Scannerlocation: class Add1 Scanner s = new Scanner(System.in); ^Add1.java:3: cannot find symbolsymbol : class Scannerlocation: class Add1 Scanner s = new Scanner(System.in); ^2 errors

Add Import statement

import java.util.Scanner;

class Add1 {public static void main(String[] args) {

Scanner s = new Scanner(System.in);int a = s.nextInt(), b = s.nextInt();int c = a+b;System.out.println("Sum is " + c);

}}

What to Import?

• You can read the Java API Specification at:• http://docs.oracle.com/javase/6/docs/api/

• Use search engines to find what you need:• For example you can use the following query to

search for “scanner” in the Java 6 API, using google:

scanner site:docs.oracle.com/javase/6/docs/api/

Functions• Use functions declared as public and static:

public static int sum(int x, int y)

• Rewriting the previous code with a function:import java.util.Scanner;class Add1 {

public static void main(String[] args) {Scanner s = new Scanner(System.in);int a = s.nextInt();int b = s.nextInt();int c = sum(a, b);System.out.println("Sum is " + c);

}public static int sum(int x, int y) {

return x+y;}

}