所以我是事件处理程序的新手,我想创建一个程序,在框架内制作一个紫色面板,如果用户单击面板区域中的鼠标按钮,然后使用键盘键入%,希望面板在面板区域中绘制一条线段。这只是测试事件处理程序。目前,我正在尝试,但是没有用。所有帮助将不胜感激。掌握了这一点之后,我想尝试一下repaint()方法,如果有人执行与以前相同的操作,我想检查面板的背景。如果您能同时帮助我,那会很棒,但这不是优先事项。谢谢。
import java.awt.Graphics; // for classes Graphics, Color, Font, Image
import java.awt.Color;
import java.awt.Font;
import java.awt.event.KeyEvent; // for classes KeyListener, MouseListener
import java.awt.event.KeyListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import javax.swing.JFrame; // for classes JFrame, JPanel, JLabel
import javax.swing.JPanel;
public class GardenGrows
{
public GardenGrows()
{
}
public static void main(String[] args)
{
GardenGrows gg = new GardenGrows();
gg.runIt();
}
// makes the frame and handles all properties of the frame
// also instantiates the Garden.java object
public void runIt()
{
JFrame frame = new JFrame ("Garden");
frame.setDefaultCloseOperation( frame.EXIT_ON_CLOSE );
frame.setLayout(null);
frame.setBackground(Color.GRAY);
frame.setSize( 1200,700);
frame.setLocation( 50, 10);
frame.setResizable(true);
frame.setVisible(true);
Garden gar = new Garden();
frame.getContentPane().add(gar);
}
}
class Garden extends JPanel implements KeyListener, MouseListener
{
private boolean mouseClicked;
private boolean keyClicked;
private int xpos;
private int ypos;
public Garden()
{
mouseClicked = false;
keyClicked = false;
addKeyListener(this);
addMouseListener(this);
setBackground(Color.PINK);
setLocation(50,50);
setSize(1000,500);
}
public void mousePressed(MouseEvent evt)
{
int x = evt.getX();
int y = evt.getY();
if(x>=50 || x<=1050 && y<=50 || y>=550)
{
mouseClicked = true;
}
}
public void mouseClicked(MouseEvent evt){}
public void mouseReleased(MouseEvent evt){}
public void mouseEntered(MouseEvent evt){}
public void mouseExited(MouseEvent evt){}
public void keyReleased(KeyEvent evt){}
public void keyPressed(KeyEvent evt){}
public void keyTyped(KeyEvent evt)
{
int letter = evt.getKeyCode();
if (letter == 13)
{
keyClicked =true;
}
}
public void paintComponent(Graphics g)
{
super.paintComponent(g);
if(keyClicked && mouseClicked)
g.drawLine(50,0,110,120);
}
}
答案 0 :(得分:2)
在JPanel中使关键侦听器工作不会那么简单,因为它不能集中。 (考虑一下JTextField,当您在其上编写文本时,它会被聚焦)。因此,为了完成这项工作,您将必须use KeyBindings。实际上,请从您的JPanel中删除KeyListener
实现,并使用KeyBindings。
public class GardenGrows {
public GardenGrows() {
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> {
// All swing applications must run on EDT Thread
GardenGrows gg = new GardenGrows();
gg.runIt();
});
}
// makes the frame and handles all properties of the frame
// also instantiates the Garden.java object
public void runIt() {
JFrame frame = new JFrame("Garden");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(null);
frame.setBackground(Color.GRAY);
frame.setSize(1200, 700);
frame.setLocation(50, 10);
frame.setResizable(true);
frame.setVisible(true);
Garden gar = new Garden();
frame.getContentPane().add(gar);
}
}
class Garden extends JPanel implements MouseListener {
private boolean mouseClicked;
private boolean keyClicked;
private int xpos;
private int ypos;
public Garden() {
mouseClicked = false;
keyClicked = false;
addMouseListener(this);
setBackground(Color.PINK);
setLocation(50, 50);
setSize(1000, 500);
getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke(KeyEvent.VK_5, KeyEvent.SHIFT_MASK),
"percentageClicked");
getActionMap().put("percentageClicked", new AbstractAction() {
@Override
public void actionPerformed(ActionEvent e) {
keyClicked = true;
repaint(); // Try to draw the line
}
});
}
public void mousePressed(MouseEvent evt) {
int x = evt.getX();
int y = evt.getY();
if (x >= 50 || x <= 1050 && y <= 50 || y >= 550) {
mouseClicked = true;
repaint(); // Try to draw the line
}
}
public void mouseClicked(MouseEvent evt) {
}
public void mouseReleased(MouseEvent evt) {
}
public void mouseEntered(MouseEvent evt) {
}
public void mouseExited(MouseEvent evt) {
}
public void paintComponent(Graphics g) {
super.paintComponent(g);
if (keyClicked && mouseClicked)
g.drawLine(50, 0, 110, 120);
}
}