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In this article, we will show you how to make an applet perform mathematical operations such as add, subtract, multiply and divide on the two numbers entered by the user and output of the mathematical computation will be presented to the user within the applet.

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An applet performing mathematical operations




//Evening handling in an applet 

import java.awt.*;
import java.awt.event.*;
import java.applet.*;

/*


*/

public class Applet6 extends Applet implements ActionListener
{
Label label1, label2, label3; 
TextField tf1, tf2, tf3;
Button b1, b2, b3, b4;
String whichButtonClk;	//This String object will tells us which button is pressed

public void init()
{
System.out.println("Initializing an applet");

label1 = new Label("Number1");
tf1= new TextField(10);

label2 = new Label("Number2");
tf2= new TextField(10);

b1 = new Button("Add");
b2= new Button("Subtract");
b3 = new Button("Multiply");
b4= new Button("Divide");


add(label1);
add(tf1);

add(label2);
add(tf2);

add(b1);
add(b2);
add(b3);
add(b4);


tf1.addActionListener(this); 	//Applet5 class registering to listen to first textfield event
tf2.addActionListener(this); 	//Applet5 class registering to listen to second textfield event
b1.addActionListener(this);	//Applet5 class registering to listen to first button event
b2.addActionListener(this);	//Applet5 class registering to listen to second button event
b3.addActionListener(this);	//Applet5 class registering to listen to third button event
b4.addActionListener(this);	//Applet5 class registering to listen to fourth button event

}


public void actionPerformed(ActionEvent ae) 
{
if(ae.getActionCommand().equals("Add") || ae.getActionCommand().equals("Subtract") ||ae.getActionCommand().equals("Multiply") ||ae.getActionCommand().equals("Divide"))// checking if an event of clicking the add/subtract/multiply/divide button is generated
{
whichButtonClk=ae.getActionCommand(); //initializing whichButtonClk to a String value of Button which is clicked
repaint();
}
}

public void paint(Graphics g)
{	
g.drawString("Please enter two numbers to perform math operations", 10,130);

if(tf1.getText().equals("") && tf2.getText().equals("")) //if the add button is clicked when textfields are empty
{	
}	
else
{
	Integer i1=  new Integer(tf1.getText());
	Integer i2= new Integer(tf2.getText());	
	int sum = i1+i2;
	int subtract=i1-i2;
	int multiply=i1*i2;
	float divide=(float)i1/(float)i2; //Casting int to float, to get precise division of two values in float
	
	if(whichButtonClk.equals("Add"))
		g.drawString("Your sum is "+ sum, 10,190);
	if(whichButtonClk.equals("Subtract"))
		g.drawString("Your subtract is "+ subtract, 10,190);
	if(whichButtonClk.equals("Multiply"))
		g.drawString("Your multiply is "+ multiply, 10,190);
	if(whichButtonClk.equals("Divide"))
		g.drawString("Your divide is "+ divide, 10,190);
}
}


}





Output


In order to run our applet using appletviewer, type the following command at command prompt-



appletviewer Applet5.java


Where Applet5.java is the name of java file that contains the code of an applet. Right after running the applet program using appletviewer a new applet window is displayed to us -





Note : After we click on the Add button, two numbers are added and their result is displayed in the applet.



After we click on the Subtract button, two numbers are subtracted and their result is displayed in the applet.



After we click on the Multiply button, two numbers are multiplied and their result is displayed in the applet.



After we click on the Divided button, first number is divided by the second number and their result is displayed in the applet.








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