我对Java AWT非常陌生。我的问题标题对您来说似乎很荒谬，对此感到抱歉。在我的应用程序中，我有三个按钮，它们在单击时显示不同的线程。现在，我想在单击特定按钮时添加一个按钮，复选框或选择列表等。例如，如果我单击“是”按钮，它将显示一个选择列表，类似这样。我该如何实现？到目前为止，这是我的代码：
import java.awt.Button;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Frame;
import java.awt.Graphics;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
public class AppWindow extends Frame implements ActionListener{
String keymsg = "Test message";
String mousemsg = "Nothing";
int mouseX=30, mouseY=30;
String msg;
public AppWindow(){
//addKeyListener(new MyKeyAdapter(this));
//addMouseListener(new MyMouseAdapter(this));
addWindowListener(new MyWindowAdapter());
}
public void paint(Graphics g){
g.drawString(msg, 150, 100);
}
//Here the window is created:
public static void main(String args[]){
AppWindow appwin = new AppWindow();
appwin.setSize(new Dimension(300,200));
appwin.setTitle("My first AWT Application");
appwin.setLayout(new FlowLayout(FlowLayout.LEFT));
appwin.setVisible(true);
Button yes,no,maybe;
yes = new Button("yes");
no = new Button("no");
maybe = new Button("maybe");
appwin.add(yes);
appwin.add(no);
appwin.add(maybe);
yes.addActionListener(appwin);
no.addActionListener(appwin);
maybe.addActionListener(appwin);
}
@Override
public void actionPerformed(ActionEvent ae) {
// TODO Auto-generated method stub
String str = ae.getActionCommand();
if(str.equals("yes")){
msg = "You pressed Yes";
}
if(str.equals("no")){
msg = "You pressed No";
}
if(str.equals("maybe")){
msg = "You pressed Maybe";
}
repaint();
}
}
class MyWindowAdapter extends WindowAdapter {
public void windowClosing(WindowEvent we){
System.exit(0);
}
}
最佳答案
描述您应该做什么的要点：
正如其他人已经提到的，最好在AWT上使用Swing，因为Swing更高级。
尽可能尝试将Paint放在JPanel或JComponent，而不是直接在Painting顶部的JFrame，
覆盖所述的paintComponent(Graphics g)方法JComponent/JPanel
除非且除非在setVisible(true)上呼叫JFrame
大小已确定。所以总的来说，这必须是
最后一次调用，一旦完成将组件添加到JFrame并JFrame的大小已由LayoutManager实现。
在您的actionPerformed(...)内部，而不是全部写ifstatement blocks，您应该遵守if-else if statementblocks。与前者相比，这样做的好处是
时间，只会触发一个事件，因此一旦上述情况发生
满意，您不希望您的代码继续检查其他
条件，这实际上不是一个好的编程
实践，恕我直言。
最重要的事情：切勿从main方法内进行类似pack（）/ setVisible（...）的调用，此类调用属于
到事件调度线程，并且必须在同一线程上完成。请
阅读Concurrency in Swing以获得更多详细信息。
查看示例程序，以更好地理解。
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class ComponentExample
{
private CustomPanel drawingBoard;
private JPanel contentPane;
private JButton yesButton;
private JButton noButton;
private JButton maybeButton;
private JComboBox cbox;
private ActionListener buttonAction = new ActionListener()
{
@Override
public void actionPerformed(ActionEvent ae)
{
JButton button = (JButton) ae.getSource();
if (cbox.isShowing())
contentPane.remove(cbox);
if (button == yesButton)
{
drawingBoard.setText("You Pressed YES.");
contentPane.add(cbox, BorderLayout.PAGE_END);
}
else if (button == noButton)
drawingBoard.setText("You Pressed NO.");
else if (button == maybeButton)
drawingBoard.setText("You Pressed MAYBE.");
/*
* revalidate()/repaint() is needed
* when the JComponent is added or
* removed from the already
* visible Container.
*/
contentPane.revalidate();
contentPane.repaint();
}
};
public ComponentExample()
{
cbox = new JComboBox(
new String[]{"I GOT IT"
, "I STILL HAD DOUBT"});
}
private void displayGUI()
{
JFrame frame = new JFrame("Component Example");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
contentPane = new JPanel();
contentPane.setOpaque(true);
contentPane.setBackground(Color.DARK_GRAY);
contentPane.setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5));
contentPane.setLayout(new BorderLayout(5, 5));
JPanel buttonPanel = new JPanel();
buttonPanel.setOpaque(true);
buttonPanel.setBackground(Color.WHITE);
yesButton = new JButton("YES");
yesButton.addActionListener(buttonAction);
noButton = new JButton("NO");
noButton.addActionListener(buttonAction);
maybeButton = new JButton("MAY BE");
maybeButton.addActionListener(buttonAction);
buttonPanel.add(yesButton);
buttonPanel.add(noButton);
buttonPanel.add(maybeButton);
contentPane.add(buttonPanel, BorderLayout.PAGE_START);
drawingBoard = new CustomPanel();
contentPane.add(drawingBoard, BorderLayout.CENTER);
frame.setContentPane(contentPane);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String... args)
{
SwingUtilities.invokeLater(new Runnable()
{
public void run()
{
new ComponentExample().displayGUI();
}
});
}
}
class CustomPanel extends JPanel
{
private String msg;
public CustomPanel()
{
msg = "";
setOpaque(true);
setBackground(Color.WHITE);
}
public void setText(String msg)
{
this.msg = msg;
repaint();
}
@Override
public Dimension getPreferredSize()
{
return (new Dimension(300, 300));
}
@Override
protected void paintComponent(Graphics g)
{
super.paintComponent(g);
g.drawString(msg, getWidth() / 3, getHeight() / 3);
}
}