Saturday, 17 August 2013

How Can We Take User Input In Applet

An applet is a Java program that runs in a Web browser.It takes user input at the run time in applet window.Due to this it used some built in functions that is stored in import java.awt.* and import java.applet.*.The functions used are:
1.Integer.parseInt() :-Change the user input to integer because the value we have entered is in integer but it will be interpreted as a String.

2.Repaint():-   when you want to re-draw your GUI because you have changed something inside.

3. Draw String():-It Returns the specified text at specified location.

WAP to implement add of two numbers from user input in applet

import java.awt.*;          //creating user interfaces and for painting graphics and images.
import java.applet.*;       //Provides the necessary classes to create an applet.

public class userInput extends Applet
{
      TextField text1, text2;        //TextField is keyword that creates the test fields
    
      public void init()                //To initialize the applet
      {
           text1 = new TextField(8);   //It specifies the length of text field   
           text2 = new TextField(8);
           add(text1);
           add(text2);
          
      }

      public void paint(Graphics g)
      {
          int x=0,y=0,z=0;
          String s1,s2,s;

// It Returns the specified text at specified location.
 g.drawString("Input a numbers which you want to add ",10,50);   
                                                              
        
try
{         

                 s1 = text1.getText();
                 x = Integer.parseInt(s1);    // Change the user input to integer
                 s2 = text2.getText();
                 y = Integer.parseInt(s2);}

          catch(Exception e){}
            z = x + y;
           s =  String.valueOf(z);      //Returns the string representation of integer value
           g.drawString("The Sum is : ",10,75);
           g.drawString(s,100,75);
    }

    public boolean action(Event event, Object obj)
    {
          repaint();   //when you want to re-draw your GUI
          return true;
    }
}

Now save this program with name userInput.java and then compile it.
Applets






Now open new notepad file and write the following code:

<html>
<body>
<applet code="userInput.class",width="200",height="200">
</applet>
</body>
</html>

Then save this file with name app.html in same folder where you have saved app.java file.

Output of this program:
Applets




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