simple calculator in java‎

Usage of calculator is common among every student but designing a calculator deals with skill of programmer.Here we shell provide you a method which simplifies the design procedure.

In this method the frame is divided into 3 panels which are described in the figure given below.

Here goes the code:-

import java.awt.*;

import javax.swing.*;

import java.awt.event.*;

import java.awt.*;

class Calculater extends JFrame 

{

JPanel northpanel,eastpanel,panel,southpanel;

JButton button[];

JButton operators[];

JTextArea area;

int op1,op2;

char oper;

Calculater(){

button=new JButton[10];//0-9 numericals

operators=new JButton[6];//for operaotrs

area=new JTextArea(5,25);

go();

}

public static void main(String arf[]){

Calculater c=new Calculater();

}

public void go(){

setTitle("ba-programmer.blogspot.in");

setLayout(new BorderLayout());

northpanel=new JPanel();//adding north pannel 

northpanel.add(area);

add(northpanel,BorderLayout.NORTH);

panel=new JPanel(new GridLayout(4,3));

button[0]=new JButton(0+"");

button[0].addActionListener(new Numbers(0));

for(int i=1;i<10;i++)

{

button[i]=new JButton(i+"");

panel.add(button[i]);

button[i].addActionListener(new Numbers(i));

}

eastpanel=new JPanel(new GridLayout(4,1));

//c for clear

operators[0]=new JButton("c");

panel.add(operators[0]);

operators[0].addActionListener(new Operations('C'));

panel.add(button[0]);

//equal operation

operators[1]=new JButton("=");

panel.add(operators[1]);

operators[1].addActionListener(new Operations('='));

add(panel,BorderLayout.CENTER);//adding panel

//addtion

operators[2]=new JButton("+");

eastpanel.add(operators[2]);

operators[2].addActionListener(new Operations('+'));

//substraction

operators[3]=new JButton("-");

eastpanel.add(operators[3]);

operators[3].addActionListener(new Operations('-'));

//divident

operators[4]=new JButton("/");

eastpanel.add(operators[4]);

operators[4].addActionListener(new Operations('/'));

//multiplication

operators[5]=new JButton("*");

eastpanel.add(operators[5]);

operators[5].addActionListener(new Operations('*'));

add(eastpanel,BorderLayout.EAST);

setVisible(true);

op1=op2=0;

setSize(300,300);

}

class Numbers implements ActionListener{

int i;

Numbers(int i){

this.i=i;

}

public void actionPerformed(ActionEvent e){

if(op1==0)

{ op1=i;

area.setText(area.getText()+op1);

}

else if(op2==0)

{ op2=i;

area.setText(area.getText()+op2);

}

}

}

class Operations implements ActionListener{

char ch;

Operations(char ch){

this.ch=ch;

}

public void actionPerformed(ActionEvent ee){

if((op1!=0 )&&(op2==0)){

oper=ch;area.setText(area.getText()+oper);}

else if(op2!=0 && (ch=='=' || ch=='C'))

{if(ch=='C')oper='C';

operators[1].setEnabled(false);

switch(oper){

case '+':

area.setText(area.getText()+"="+(op1+op2));

break;

case '-':

area.setText(area.getText()+"="+(op1-op2));

break;

case '*':

area.setText(area.getText()+"="+(op1*op2));

break;

case '/':

area.setText(area.getText()+"="+(float)(op1/op2));

break;

case 'C':

operators[1].setEnabled(true);

area.setText("");op1=op2=0;

break;

}

}

}

}

}

source code:-

ClickHere to download (JFrame).

ClickHere to download (Applet).

Try this out:-

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