java 画矩形

你的代码有问题，你的类本身是frame，你也在类中绘制，但是你却没有显示，而是另外定义了一个frame来显示，你修改一下：

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import java.awt.Color;

import java.awt.Component;

import java.awt.Frame;

import java.awt.Graphics;

import java.awt.Rectangle;

public class FrameTest extends Frame {

/**

* @param args

*/

public void paint(Graphics g)

{

super.paint(g);

g.setColor(Color.black);

g.fillRect(100, 100, 30, 30);

try {

Thread.sleep(500);

}

catch (Exception ex) {

ex.printStackTrace();

}

//repaint();

}

FrameTest()

{

super("title");

setLocation(100,100);

setSize(600,400);

setVisible(true);

}

public static void main(String[] args) {

// TODO Auto-generated method stub

FrameTest ft=new FrameTest();

}

}

这样应该没问题了。

java画矩形

直接说event是简单，不过总要试一试才敢拿上来讲，所以就全写上来了。。。

import java.awt.Color;

import java.awt.Graphics;

import java.awt.Point;

import java.awt.Rectangle;

import java.awt.event.MouseEvent;

import java.util.ArrayList;

import javax.swing.JFrame;

import javax.swing.JPanel;

import javax.swing.event.MouseInputAdapter;

import javax.swing.event.MouseInputListener;

public class Test {

public static void main(String[] args) {

JFrame frame = new JFrame();

frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

frame.setContentPane(new PaintingPanel());

frame.setBounds(100, 100, 400, 400);

frame.setVisible(true);

}

}

class PaintingPanel extends JPanel {

ArrayListRectangle list;

Rectangle current;

public PaintingPanel() {

list = new ArrayListRectangle();

addMouseMotionListener(mouseHandler);

addMouseListener(mouseHandler);

}

MouseInputListener mouseHandler = new MouseInputAdapter() {

Point startPoint;

public void mousePressed(MouseEvent e) {

startPoint = e.getPoint();

current = new Rectangle();

}

public void mouseReleased(MouseEvent e) {

makeRectangle(startPoint, e.getPoint());

if (current.width 0 current.height 0) {

list.add(current);

current = null;

repaint();

}

}

public void mouseDragged(MouseEvent e) {

if (current != null) {

makeRectangle(startPoint, e.getPoint());

repaint();

}

}

private void makeRectangle(Point p1, Point p2) {

int x = Math.min(p1.x, p2.x);

int y = Math.min(p1.y, p2.y);

int w = Math.abs(p1.x - p2.x);

int h = Math.abs(p1.y - p2.y);

current.setBounds(x, y, w, h);

}

};

public void paint(Graphics g) {

super.paint(g);

g.setColor(Color.BLACK);

for (Rectangle rect : list) {

g.fillRect(rect.x, rect.y, rect.width, rect.height);

}

if (current != null) {

g.drawRect(current.x, current.y, current.width, current.height);

}

}

}

java中做一个按钮，点击按钮后画一个矩形的代码怎么写？

兄弟帮你写了一个：

import java.awt.Button;

import java.awt.Color;

import java.awt.Frame;

import java.awt.Graphics;

import java.awt.event.ActionEvent;

import java.awt.event.ActionListener;

import java.awt.event.WindowAdapter;

import java.awt.event.WindowEvent;

import java.util.Random;

public class Print {

public static void main(String[] args) {

new Te();

}

}

class Te extends Frame implements ActionListener {

Color cc = Color.red;

int x = -20, y = -50;

Random r = new Random();

public Te() {

this.setLayout(null);

Button b = new Button("画圆");

this.add(b);

b.setBounds(30,30,50,50);

b.addActionListener(this);

this.addWindowListener(new WindowAdapter () {

@Override

public void windowClosing(WindowEvent e) {

System.exit(0);

}

});

this.setBounds(200,200,500,400);

this.setVisible(true);

}

public void actionPerformed(ActionEvent e) {

this.cc = Color.red;

this.x = r.nextInt(400);

do {

int x1 = r.nextInt(300);

this.y = x1;

} while (this.y 50);

this.repaint();

}

@Override

public void paint(Graphics g) {

Color c = g.getColor();

g.setColor(cc);

g.drawRect(x,y,50,50);

g.setColor(c);

}

}

新闻名称：java画矩形代码 用java画一个图形
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