computer programming (tmk 3102) lecture notes 4

8/9/2019 COMPUTER PROGRAMMING (TMK 3102) LECTURE NOTES 4

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TMK 3102-Chap 4: Input & Output 1

Chapt er 4 : Input & Out put

Session Plan (Week 4):

To understand:the concept of input & output in JAVA


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Syst em .out .pr in t ln St a t em entpublic class Hello {

public static void main(String[] args){

System.out.println(Hello World);

System.out.println(Welcome to Java );}

}

C:\> javac Hello.java

Hello World

Welcome to Java


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Syst em .out .pr in t St a t em ent

public class Hello {


System.out.print(Hello World);

System.out.println(Welcome to Java );}

}


C:\> java Hello

Hello World Welcome to Java


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Esc ape Charac t er

public class Hello {


System.out.println(Hello World!! \n Welcome to Java );

}}


Hello World!!

Welcome to Java


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Esc ape Charac t er

\n newline. Position the cursor to the beginning of nextline

\t horizontal tab. Move the cursor to the next tabstop

\r carriage-return. Position the cursor to thebeginning of the current line, do not advance tothe next line

\\ used to print a backslash character

\ Single quote. Used to print single quote character\ double quote. Used to print double quote character


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Using Sc anner Class For input

import java.util.*;

public class UsingScannerClass {


Scanner input = new Scanner(System.in);int age;

System.out.print("How old are you?");

age = input.nextInt();

System.out.println("Hi!!, You are "+age+ " years old");

}}


C:\> java Hello

How old are you? 17

Hi!!, you are 17 years Old

age 17


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Display ing i n Graphic s

You can use the showMessageDialogmethod in the JOptionPane class.

JOptionPane is one of the manypredefined classes in the Javasystem, which can be reused ratherthan reinventing the wheel.


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The show MessageDia logMethod

JOptionPane.showMessageDialog(null,

"Welcome to Java!",

"Example 1.2 Output",

JOptionPane.INFORMATION_MESSAGE));


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Tw o Ways t o Invoke t he Met hod

There are several ways to use the showMessageDialogmethod. For the time being, all you need to know aretwo ways to invoke it.

One is to use a statement as shown in the example:JOptionPane.showMessageDialog(null, x,y, JOptionPane.INFORMATION_MESSAGE));

where x is a string for the text to be displayed, and y isa string for the title of the message dialog box.

The other is to use a statement like this:JOptionPane.showMessageDialog(null, x);

where x is a string for the text to be displayed.


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Example

import javax.swing.JOptionPane;

public class Welcome {

public static void main(String[] args) {

String name;name = JOptionPane.showInputDialog("What is Your

Name?");

JOptionPane.showMessageDialog(null,"Hi!!! "+name+"\nWelcome\nTo\nJava\nWorld");

}

}


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Example




String name;name = JOptionPane.showInputDialog("Whatis Your Name?");

JOptionPane.showMessageDialog(null,

"Hi!!! "+name+"\nWelcome\nTo\nJava\nWorld");

}

}


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Example




String name;

name = JOptionPane.showInputDialog("What is YourName?");

JOptionPane.showMessageDialog(null,"Hi!!! "+name+"\nWelcome\nTo\nJava\nWorld");

}}


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Exerc ise

Write the java program using the givenpseudo code.

1. Start

2. Get the value of radius

3. Calculate area where area = x r x r

4. Display area

5. End


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Thank You

computer programming (tmk 3102) lecture notes 4

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