用java编程一个计算器.doc

import java.awt.*; import java.awt.event.*; import javax.swing.*; public class Calculator extends JFrame{ private Container container; private JTextField tf; private Panel panel; private String cmd; private double result; private boolean start; Calculator(){ super(java简易计算器); container = getContentPane(); container.setLayout(new BorderLayout()); tf = new JTextField(0.0); container.add(tf,BorderLayout.NORTH); tf.setHorizontalAlignment(JTextField.RIGHT); tf.setEditable(false); panel = new Panel(); container.add(panel); start = true; result = 0; cmd = =; ActionListener insert = new InsertAction(); ActionListener command = new CommandAction(); addButton(1,insert); addButton(2,insert); addButton(3,insert); addButton(0,insert); addButton(*,command); addButton(Back,insert); addButton(4,insert); addButton(5,insert); addButton(6,insert); addButton(+,command); addButton(/,command); addButton(Clear,insert); addButton(7,insert); addButton(8,insert); addButton(9,insert); addButton(-,command); addButton(.,insert); addButton(=,command); setSize(400,300); } private void addButton(String str,ActionListener listener){ JButton button=new JButton(str); button.addActionListener(listener); panel.setLayout(new GridLayout(3,6)); panel.add(button); } private class InsertAction implements ActionListener{ public void actionPerformed(ActionEvent event){ String input=event.getActionCommand(); if (start) { tf.setText(); start=false; } if(input.equals(Back)) { String str=tf.getText(); if(str.length()0) tf.setText(str.substring(0,str.length()-1)); } else if(input.equals(Clear))