import java.awt.*;
import javax.swing.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import javax.swing.event.*;
import java.awt.geom.*;
import java.util.*;
public class test extends JFrame implements ActionListener, MouseListener {
private Vector<String> vlist = new Vector<String> ();
private int mouseX, mouseY;
Canvas c = new Canvas();
public test () {
setSize(400,400);
addMouseListener(this);
}
public static void main(String[] args) {
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
test frame = new test();
//frame.setBackground(Color.yellow);
frame.setVisible(true);
}
});
}
public void actionPerformed(ActionEvent ae) {
}
@Override
public void paint(Graphics g) {
Shape circle = new Ellipse2D.Float(100f, 100f, 100f, 100f);
Graphics2D ga = (Graphics2D)g;
ga.draw(circle);
}
public void move() {
}
public void drawCircle(int x, int y) {
}
public void mouseClicked(MouseEvent e) {
repaint();
}
public void mouseExited(MouseEvent e) {
}
public void mousePressed(MouseEvent e) {
this.mouseX=e.getX();
this.mouseY=e.getY();
}
public void mouseReleased(MouseEvent e) {
}
public void mouseEntered(MouseEvent e) {
}
}
我想编写一个测试程序来学习java中的图形编程。运行上面的代码，会自动绘制圆圈。为什么paint()方法会自动执行？我单击鼠标时要创建的圆圈。
最佳答案
向类添加属性。
boolean draw;
用
包围paint(...) 中的代码
if (draw) {
// existing code
}
这将使程序仅在 draw 为 true 时才进行绘制。最初，它是假的，所以它不会绘制任何东西。单击鼠标时，值属性 draw 将为 true。
public void mouseClicked(MouseEvent e) {
draw = true;
repaint();
}
关于java Paint() 自动执行？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/8074898/