Programming and Problem Solving with Java

CASE STUDY^419

// Instantiate button objects

add = newJButton("+");

subtract = newJButton("-");

clear = newJButton("Clear");

// Register the button listeners

add.addActionListener(operation);

subtract.addActionListener(operation);

clear.addActionListener(clearOperation);

// Add interface elements to calcFrame
calcFrame = newJFrame(); // Give the frame a value
calcFrame.setSize( 300 , 200 ); // Specify size of frame
// Set close operation to exit
calcFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
calcPane = calcFrame.getContentPane(); // Get the content pane
calcPane.setLayout(new GridLayout( 4 , 2 )); // Set the layout manager
calcPane.add(resultLabel);
calcPane.add(register);
calcPane.add(entryLabel);
calcPane.add(inputField);
calcPane.add(add);
calcPane.add(subtract);
calcPane.add(clear);
calcFrame.setVisible(true); // Show the frame
}
}

When we run the application, it displays a window like the one here: