Java编程简单问题?
我想做一个简单计算器的界面,下面源代码:
已经能通过编译但是不能执行,那位高手有空时帮忙看一下,小弟在此先谢过了.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class Graphics_Count2
{
public static void main(String args[])
{
new FrameIO();
}
}
class FrameIO extends JFrame
{
JTextField IOput;
JButton btn0,btn1,btn2,btn3,btn4,btn5,btn6,btn7,btn8,btn9;
JButton btnAdd,btnSub,btnMul,btnDiv,btnEqual,btnPoint;
FrameIO()
{
super( "简单计算 ");
IOput = new JTextField(20);
btn0 = new JButton( "0 ");btn1 = new JButton( "1 ");
btn2 = new JButton( "2 ");btn3 = new JButton( "3 ");
btn4 = new JButton( "4 ");btn5 = new JButton( "5 ");
btn6 = new JButton( "6 "); btn7 = new JButton( "7 ");
btn8 = new JButton( "8 "); btn9 = new JButton( "9 ");
btnAdd = new JButton( "+ "); btnSub = new JButton( "- ");
btnMul = new JButton( "* "); btnDiv = new JButton( "/ ");
JPanel p = new JPanel();
p.setLayout(new GridLayout(4,4));
p.add(btnAdd); p.add(btn1); p.add(btn2); p.add(btn3);
p.add(btnSub); p.add(btn4); p.add(btn5); p.add(btn6);
p.add(btnMul); p.add(btn7); p.add(btn8); p.add(btn9);
p.add(btnDiv); p.add(btn0); p.add(btnPoint); p.add(btnEqual);
Container container = getContentPane();
container.setLayout(new BorderLayout());
container.add(IOput,BorderLayout.NORTH);
container.add(p,BorderLayout.SOUTH);
container.add(new JButton( "EXIT "),BorderLayout.EAST);
setSize(300,300);
setVisible(true);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}
[解决办法]
/**
我这里有一个计算器的例子，愿能为你提供一些参考
*/
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class Calculator
{
public static void main(String[] args)
{
CalculatorFrame frame = new CalculatorFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
}
/**
A frame with a calculator panel.
*/
class CalculatorFrame extends JFrame
{
public CalculatorFrame()
{
setTitle( "Calculator ");
CalculatorPanel panel = new CalculatorPanel();
add(panel);
pack();
}
}
/**
A panel with calculator buttons and a result display.
*/
class CalculatorPanel extends JPanel
{
public CalculatorPanel()
{
setLayout(new BorderLayout());
result = 0;
lastCommand = "= ";
start = true;
// add the display
display = new JButton( "0 ");
display.setEnabled(false);
add(display, BorderLayout.NORTH);
ActionListener insert = new InsertAction();
ActionListener command = new CommandAction();
// add the buttons in a 4 x 4 grid
panel = new JPanel();
panel.setLayout(new GridLayout(4, 4));
addButton( "7 ", insert);
addButton( "8 ", insert);
addButton( "9 ", insert);
addButton( "/ ", command);
addButton( "4 ", insert);
addButton( "5 ", insert);
addButton( "6 ", insert);
addButton( "* ", command);
addButton( "1 ", insert);
addButton( "2 ", insert);
addButton( "3 ", insert);
addButton( "- ", command);
addButton( "0 ", insert);
addButton( ". ", insert);
addButton( "= ", command);
addButton( "+ ", command);
add(panel, BorderLayout.CENTER);
}
/**
Adds a button to the center panel.
@param label the button label
@param listener the button listener
*/
private void addButton(String label, ActionListener listener)
{
JButton button = new JButton(label);
button.addActionListener(listener);
panel.add(button);
}
/**
This action inserts the button action string to the
end of the display text.
*/
private class InsertAction implements ActionListener
{
public void actionPerformed(ActionEvent event)
{
String input = event.getActionCommand();
if (start)
{
display.setText( " ");
start = false;
}
display.setText(display.getText() + input);
}
}
/**
This action executes the command that the button
action string denotes.
*/
private class CommandAction implements ActionListener
{
public void actionPerformed(ActionEvent event)
{
String command = event.getActionCommand();
if (start)
{
if (command.equals( "- "))
{
display.setText(command);
start = false;
}
else
lastCommand = command;
}
else
{
calculate(Double.parseDouble(display.getText()));
lastCommand = command;
start = true;
}
}
}
/**
Carries out the pending calculation.
@param x the value to be accumulated with the prior result.
*/
public void calculate(double x)
{
if (lastCommand.equals( "+ ")) result += x;
else if (lastCommand.equals( "- ")) result -= x;
else if (lastCommand.equals( "* ")) result *= x;
else if (lastCommand.equals( "/ ")) result /= x;
else if (lastCommand.equals( "= ")) result = x;
display.setText( " " + result);
}
private JButton display;
private JPanel panel;
private double result;
private String lastCommand;
private boolean start;
}
