给你帖一个,这个时核心技术里的一个源码,看书是最好的学习之路。
例子最好做又源码的,并且泡论坛对学习帮助不大,对提高倒是有点作用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.show();
}
}/**
A frame with a calculator panel.
*/
class CalculatorFrame extends JFrame
{
public CalculatorFrame()
{
setTitle("Calculator");
setSize(WIDTH, HEIGHT); Container contentPane = getContentPane();
CalculatorPanel panel = new CalculatorPanel();
contentPane.add(panel);
} public static final int WIDTH = 200;
public static final int HEIGHT = 200;
}
/**
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 JTextField("0");
display.setEditable(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 evt)
{
String command = evt.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 JTextField display;
private JPanel panel;
private double result;
private String lastCommand;
private boolean start;
}
例子最好做又源码的,并且泡论坛对学习帮助不大,对提高倒是有点作用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.show();
}
}/**
A frame with a calculator panel.
*/
class CalculatorFrame extends JFrame
{
public CalculatorFrame()
{
setTitle("Calculator");
setSize(WIDTH, HEIGHT); Container contentPane = getContentPane();
CalculatorPanel panel = new CalculatorPanel();
contentPane.add(panel);
} public static final int WIDTH = 200;
public static final int HEIGHT = 200;
}
/**
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 JTextField("0");
display.setEditable(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 evt)
{
String command = evt.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 JTextField display;
private JPanel panel;
private double result;
private String lastCommand;
private boolean start;
}
我们还年轻牛奶会有的奶牛也会有的
可天天在 csdn 混这些会有吗 ??
看了一下你的源程序,有几个问题:
1.类名首字母应该大写,dialog应为Dialog,否则编译器就不会放过你;
2.pan是用来干什么的,不清楚。Panel用来布局界面,整体布局可以采用Frame的缺省布局管理器BorderLayout,分为上、下两部分,分别用panel来填充,上面的panel可以放一个textfield,占大部分空间的下面的panel可以放数字button,采用TGridLayout;
3.采用布局管理器时,控件大小是由布局管理器来控制的,所起setSize不会起作用。