Creating a calculator

Question

i am trying to create a calculator and I am not sure how to set up the multiply, divide, add, subtract or the equal keys. i am currently trying " inputField.getText" to get the number , but how do i then get the second number from the same field after pressing one of the functions and set that up so that the equal key will give me the answer???? Any help would be appreciated
public void actionPerformed(ActionEvent event);
                    if(event.getSource() == sevenButton)
                         seven();
                    if else(event.getSource() == eightButton)
                         eight();
                    if else(event.getSource() == nineButton)
                         nine();
                    if else (event.getSource() == divideButton)
                         divide();
                    if else(event.getSource() == fourButton)
                         four();
                    if else(event.getSource () == fiveButton)
                         five();
                    if else(event.getSource () == sixButton)
                         six();
                    if else (event.getSource () == multiplyButton)
                         multiply();
                    if else (event.getSource () == oneButton)
                         one();
                    if else(event.getSource () == twoButton)
                         two();
                    if else (event.getSource () == threeButton)
                         three ();
                    if else(event.getSource () == minusButton)
                         minus();
                    if else(event.getSource () == zeroButton)
                         zero();
                    if else(event.getSource () == equalsButton)
                         equals();
                    if else(event.getSource () == addButton)
                         add();
               {     //end actionperformed
               public void seven()
                    inputField.setText(" ");
                    inputField.setText("7");
               public void eight()
                    inputField.setText(" ");
                    inputField.setText("8");
               public void nine()
                    inputField.setText(" ");
                    inputField.setText("9")'
               public void divide()
                    num1 = Integer.parseInt(inputField.getText());
          }     //end class

Answer 1

Seems to me that a real calculator stores the number from the display somewhere when (e.g.) the Plus key is pressed, then when the Equals key is pressed it adds that stored number to the current display and displays the result. Why don't you imitate that behaviour?