Question

我已经可以在MousePressed和MouseReleased的面板中创建一个球，并使用MotionListener更新坐标，并在鼠标悬停时更改球的颜色。这在myPanel类中工作正常，因为面板已定义尺寸，鼠标在其中工作。但是我现在必须做什么，并且不确定如何使Ball类扩展Component并实现MouseListener。因此，我必须在Ball类中使用MouseEntered来改变球的颜色。帮助

//Ball
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class Ball extends JComponent implements MouseListener{

public int x,y,r;
public Color c = Color.BLUE;
private int distance = 0;

public Ball(int X, int Y, int R){
    super();
    x=X;
    y=Y;
    r=R;
addMouseListener(this);
}

public void draw(Graphics g){
    g.setColor(c);
    g.fillOval(x-r, y-r, 2*r, 2*r);
}

public void mousePressed(MouseEvent me){}
public void mouseReleased(MouseEvent me){ }
public void mouseClicked(MouseEvent me){}
public void mouseEntered(MouseEvent me){
c = Color.ORANGE;
}
public void mouseExited(MouseEvent me){}

}


//myPanel
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.MouseInputAdapter;

public class myPanel extends JPanel implements MouseListener{

private Color c = new Color(150,200,100);
public Ball ball = new Ball(100,100,50);
private Point mouseCoords = new Point();

public myPanel(){
    super();
    setLayout(new FlowLayout());
    addMouseListener(this);
    add(ball);
}


public void paintComponent(Graphics g){
    super.paintComponent(g);
    ball.draw(g);
}

public void mousePressed(MouseEvent me){
    ball.x = me.getX();
    ball.y = me.getY();
    labelPanel.setX(me.getX());  //Report x and y values
    labelPanel.setY(me.getY());
//  ball.c = Color.RED;         //change color on click
    repaint();
}
public void mouseReleased(MouseEvent me){}
public void mouseMoved(MouseEvent me) {}
public void mouseClicked(MouseEvent me){}
public void mouseEntered(MouseEvent me){}
public void mouseExited(MouseEvent me){}

}

// myFrame
import java.awt.*;
import javax.swing.*;

public class myFrame extends JFrame{

public myPanel left = new myPanel();
public labelPanel right = new labelPanel();

public myFrame(){

    super("This is my Frame");
    setLayout(new BorderLayout());
    setSize(900,700);
    add(left,BorderLayout.CENTER);
    add(right,BorderLayout.EAST);
    setVisible(true);
}

public static void main(String[] args){
    myFrame mF = new myFrame();
    mF.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}

}


//labelPanel
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.MouseInputAdapter;



public class labelPanel extends JPanel{

public static JLabel xCoord = new JLabel("X=",JLabel.RIGHT);
public static JLabel yCoord = new JLabel("Y=",JLabel.RIGHT);
public Color c = new Color(100,200,10);

public labelPanel() {
    super();
    setBackground(c);
    setLayout(new GridLayout(2,1));
    add(xCoord);
    add(yCoord);
}

public static void setX(int x){
    xCoord.setText("X=" + x);
}
public static void setY(int y){
    yCoord.setText("Y=" + y);
}

}

因此，如果你运行代码，它就像前面提到的那样工作，但我不知道如何将Ball类定义为Component / JComponent，以便它实现MouseEntered

Answer 1

在构造函数中使用addMouseListener(this)：

public Ball(int X, int Y, int R){
    super();
    x=X;
    y=Y;
    r=R;
    addMouseListener(this);
}

并从draw()方法中删除它。

此外，如果您可能要考虑覆盖paint(Graphics g)。这将允许Swing确定何时绘制。您始终可以通过致电repaint();或致电paint()来手动选择抽奖时间。 repaint()绘制此组件和所有子组件，并清除组件。 paint()只绘制此组件，而不是子组件，除非包含在paint方法中，否则不会清除屏幕。

告诉我，如果这不能解决它。

Java Swing：在mouseEntered上改变球的颜色

1 个答案: