Taking User Input in Java

Taking InputTaking InputJavaJava

Md. Eftakhairul IslamMd. Eftakhairul Islam

[email protected]@gmail.com

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Scanner ClassScanner Class

The Scanner class is a class in The Scanner class is a class in java.util, which allows the user to java.util, which allows the user to read values of various types by its read values of various types by its method.method.

In Java documentationIn Java documentation

Link:Link: http://java.sun.com/j2se/1.5.0/docs/api/java/util/Scanner.html

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Scanner Class MethodsScanner Class Methods

BRAC University Computer ClubBRAC University Computer Club 33

Method Returns

int nextInt() Returns the next token as an int.

long nextLong() Returns the next token as a long

float nextFloat() Returns the next token as a float.

double nextDouble() Returns the next token as a long

String next() Finds and returns the next complete token from this scanner and returns it as a string; a token is usually ended by whitespace such as a blank or line break

String nextLine() Returns the rest of the current line, excluding any line separator at the end.

//Import the class//Import the class

import java.util.Scanner;import java.util.Scanner;

public class NumericInput{public class NumericInput{

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

// Declarations// Declarations

Scanner in = new Scanner(System.in);Scanner in = new Scanner(System.in);

int integer = in.nextInt();int integer = in.nextInt();

long longInteger = in.nextLong();long longInteger = in.nextLong();

float realNumber = in.nextFloat();float realNumber = in.nextFloat();

double doubleReal = in.nextDouble();double doubleReal = in.nextDouble();

String stringLine = in.nextLine();String stringLine = in.nextLine();

String stringStoken= in.next();String stringStoken= in.next();

System.out.println("Enter an integer = “+ integer+”, a long System.out.println("Enter an integer = “+ integer+”, a long integer =“+ longInteger +“,a floating-point = “+ integer =“+ longInteger +“,a floating-point = “+ doubleReal+” ,and a string = “+ stringStoken+”, It will print doubleReal+” ,and a string = “+ stringStoken+”, It will print whole line = “+ stringLine);whole line = “+ stringLine);

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Scanner Class ExampleScanner Class Example

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BufferedReaderBufferedReader

import java.io.*;import java.io.*;

Public class Taking inputPublic class Taking input {{ Public static void main(String [] args) Public static void main(String [] args) throws IOExceptionthrows IOException {{ BufferedReader x = new BufferedReader(new BufferedReader x = new BufferedReader(new

InputStreamReader(System.in));InputStreamReader(System.in));

// // String box;String box;//String box=x.readLine();//String box=x.readLine();

Converting x in IntegerConverting x in Integerint n=Integer.parseInt(int n=Integer.parseInt(xx.readLine());.readLine());

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//Converting x in Float //Converting x in Float float f=Float.parseFloat(x.readLine());float f=Float.parseFloat(x.readLine());

//Converting x in Double//Converting x in Double double d=Double.parseDouble(x.readLine());double d=Double.parseDouble(x.readLine()); //Converting x in Long//Converting x in Long long l=Long.parseLong(x.readLine());long l=Long.parseLong(x.readLine());

//Converting x in Byte//Converting x in Byte byte b=Byte.parseByte(x.readLine());byte b=Byte.parseByte(x.readLine()); }}}}


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JOptionPaneJOptionPane

//importing class from java //importing class from java

Import javax.swing.JOptionPane.*;Import javax.swing.JOptionPane.*;

Main()………Main()………

String s = JOptionPane.showInputDialog ("String s = JOptionPane.showInputDialog ("Enter any Enter any numbernumber");");

//Converting x in integer//Converting x in integer

int p = Integer.parseInt(x);int p = Integer.parseInt(x);//Converting x in Double//Converting x in Doubledouble d = Double.parseDouble(x.readLine());double d = Double.parseDouble(x.readLine());


Take input from fileTake input from file

// Declarations // Declarations Scanner inFile = new Scanner(new Scanner inFile = new Scanner(new

FileReader("File name with directories"));FileReader("File name with directories"));

//Read token by token from file //Read token by token from file

String stringStoken= inFile.next(); String stringStoken= inFile.next();

//Read Line by Line from file //Read Line by Line from file

String stringLine = inFile.nextLine();String stringLine = inFile.nextLine();

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Reading data from InternetReading data from Internet import java.net.*;import java.net.*; import java.io.*;import java.io.*; public class WebSiteReader {public class WebSiteReader { public static void main(String args[]){public static void main(String args[]){ String nextLine;String nextLine; try{try{ // Create the URL obect that points & at the default file index.html// Create the URL obect that points & at the default file index.html URL url = new URL("http://rainbd.freelance.com.bd/index.html" );URL url = new URL("http://rainbd.freelance.com.bd/index.html" ); URLConnection urlConn = url.openConnection();URLConnection urlConn = url.openConnection(); BufferedReader buff= new BufferedReader(new InputStreamReader(urlConn.getInputStream()));BufferedReader buff= new BufferedReader(new InputStreamReader(urlConn.getInputStream())); // Read and print the lines from index.html// Read and print the lines from index.html while (true){while (true){ nextLine =buff.readLine(); nextLine =buff.readLine(); if (nextLine !=null){if (nextLine !=null){ System.out.println(nextLine); System.out.println(nextLine); }else{}else{ break;break; }} }} } catch(Exception e){} catch(Exception e){ System.out.println("Please read the exception carefully:" + e.toString());System.out.println("Please read the exception carefully:" + e.toString()); } } }} } }

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Difference between println & printDifference between println & print

System.out.println(“java”);System.out.println(“java”);

System.out.println(“world”);System.out.println(“world”);

>>

JavaJava

worldworld

> >

(Different line )(Different line )


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System.out.print()System.out.print()

System.out.print(“java”);System.out.print(“java”);

System.out.print(“world”);System.out.print(“world”);

>>

javaworld>javaworld>

(Same line)(Same line)


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out.println( );out.println( );

import static java.lang.System.out;import static java.lang.System.out;

main()…….main()…….

out.println(“shortcut of println”);out.println(“shortcut of println”);

out.print(“shortcut of print”);out.print(“shortcut of print”);


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…….Thank You…..Thank You….


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Taking User Input in Java