import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.geom.Ellipse2D;
import java.util.Random;import javax.swing.JFrame;
import javax.swing.JPanel;
public class launch {
public static void main(String[] args) {
JFrame frame=new JFrame();
Circle circle=new Circle();
frame.add(circle);
frame.setBounds(0,0,400,400);
frame.setVisible(true);
}
}class Circle extends JPanel {
Random rand;
Ellipse2D circle;
public void paint(Graphics g){
Graphics2D g2=(Graphics2D)g;
rand=new Random();
g2.setColor(Color.RED);
circle.setFrame(rand.nextInt(50),rand.nextInt(50), 50, 50);
g2.fill(circle);
}
}
为什么我想在随机位置显示的圆没出现呢?求解 谢谢各位了
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.geom.Ellipse2D;
import java.util.Random;import javax.swing.JFrame;
import javax.swing.JPanel;
public class launch {
public static void main(String[] args) {
JFrame frame=new JFrame();
Circle circle=new Circle();
frame.add(circle);
frame.setBounds(0,0,400,400);
frame.setVisible(true);
}
}class Circle extends JPanel {
Random rand;
Ellipse2D circle;
public void paint(Graphics g){
Graphics2D g2=(Graphics2D)g;
rand=new Random();
g2.setColor(Color.RED);
circle.setFrame(rand.nextInt(50),rand.nextInt(50), 50, 50);
g2.fill(circle);
}
}
为什么我想在随机位置显示的圆没出现呢?求解 谢谢各位了
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import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.geom.Ellipse2D;
import java.util.Random;import javax.swing.JFrame;
import javax.swing.JPanel;
public class Launch {
public static void main(String[] args) {
java.awt.EventQueue.invokeLater(new Runnable(){
public void run(){
JFrame frame=new JFrame();
Circle circle=new Circle();
frame.add(circle);
frame.setBounds(0,0,400,400);
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
});
}
static class Circle extends JPanel {
Random rand=new Random();
Ellipse2D circle = new Ellipse2D.Double();
public void paintComponent(Graphics g){
Graphics2D g2=(Graphics2D)g;
g2.setPaint(Color.RED);
circle.setFrame(rand.nextInt(50),rand.nextInt(50), 50, 50);
g2.fill(circle);
}
}
}
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.geom.Ellipse2D;
import java.util.Random;import javax.swing.JFrame;
import javax.swing.JPanel;
public class launch {
public static void main(String[] args)
{
JFrame frame=new JFrame();
Circle circle=new Circle();
frame.setBounds(0,0,400,400); frame.add(circle);
frame.setVisible(true); }
}class Circle extends JPanel
{
Random rand;
//你没有实例化这个对象
Ellipse2D circle = new Ellipse2D.Double();
public void paint(Graphics g){ Graphics2D g2=(Graphics2D)g;
rand=new Random();
g2.setColor(Color.RED);
circle.setFrame(rand.nextInt(50),rand.nextInt(50), 50, 50);
g2.fill(circle);
}
}
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.geom.Ellipse2D;
import java.util.Random;import javax.swing.JFrame;
import javax.swing.JPanel;
public class launch {
public static void main(String[] args) {
JFrame frame=new JFrame();
Circle circle=new Circle();
frame.add(circle);
frame.setBounds(0,0,400,400);
frame.setVisible(true); }
}class Circle extends JPanel {
Random rand;
Ellipse2D circle;
public void paint(Graphics g){
Graphics2D g2=(Graphics2D)g;
rand=new Random();
g2.setColor(Color.RED);
circle.setFrame(rand.nextInt(50),rand.nextInt(50), 50, 50);
g2.fill(circle);
}
}