How to make a Calculator using Java

This Example will teach you how to make the Calculator programming in java step by step in right way. this is the professional way to do the calculation part.

First Step Create the Variable

 int operation;

Create the Method Sum. in order to calculate the total using switch case statement.

 public void getSum(int operation)
            {
            if(txtNum1.getText().length()!=0 && txtNum2.getText().length()!=0)
            {
                switch(operation)
                {
                case 1:
                    txtResult.setText(""+(Double.parseDouble(txtNum1.getText())+Double.parseDouble(txtNum2.getText())));
                break;
                case 2:
                    txtResult.setText(""+(Double.parseDouble(txtNum1.getText())-Double.parseDouble(txtNum2.getText())));
                break;
                case 3:
                     txtResult.setText(""+(Double.parseDouble(txtNum1.getText())*Double.parseDouble(txtNum2.getText())));
                break;
                case 4:
                    txtResult.setText(""+(Double.parseDouble(txtNum1.getText())/Double.parseDouble(txtNum2.getText())));
                break;
                } 
            }
            }

Paste the Code side the + Button

operation=1; means go to check case 1

operation=1;
getSum(operation);

Paste the Code side the – Button

operation=2; means go to check case 2

 operation=2;
 getSum(operation);

Paste the Code side the * Button

operation=3; means go to check case 3

operation=3;
getSum(operation);

Paste the Code side the / Button

operation=4; means go to check case 4

operation=4;
getSum(operation);

i have attached the video link below. which will do this tutorials step by step.