Programming and Problem Solving with Java

427

8.Most of the code in the Calculatorapplication involves input/output. The code
is long, but the concepts are simple. Examine the code below and mark the
statements associated with creating the frame and content pane as F; the
statements associated with handling buttons as B; and the statements that
create the buttons, register the listeners with them, and place the buttons into
the frame as FB. Notice that all the comments have been removed; you have to
read and understand the actual code to answer this question and Exercise 9.

importjava.awt.*;

importjava.awt.event.*;

importjavax.swing.*;

public classCalculator

{

staticJTextField inputField;

staticJLabel register;

static doubleresult;

staticJFrame calcFrame;

staticContainer calcPane;

staticNumericHandler operation;

staticClearHandler clearOperation;

staticJLabel resultLabel;

staticJLabel entryLabel;

staticJButton add;

staticJButton subtract;

staticJButton clear;

static classNumericHandler implementsActionListener

{

public voidactionPerformed(ActionEvent event)

{

doublesecondOperand;

String whichButton;

secondOperand =

Double.parseDouble(inputField.getText());

whichButton = event.getActionCommand();

if(whichButton.equals("+"))

result = result + secondOperand;

else

result = result – secondOperand;