Java mouseListener的mousemove无法正常工作

Question

I am trying to make a plotting program, the program should show the point the user is currently on, i tried using mousemove for this function (using console for now to view result) but it's not working.

public class drawArea extends JPanel implements MouseListener {
Image img;
int w=580;
int h=580;
String equation = "";
int clicks = 0;

public drawArea(){
    init();
    this.addMouseListener(this);
}

private void init(){
    setPreferredSize( new Dimension( w, h ) );
    setVisible(true);
    img = new ImageIcon("assets/Graph.png").getImage();
}

private void initializeGrid(Graphics g) {

    Graphics2D g2d = (Graphics2D) g;
    g2d.drawImage(img, 0, 0, this);

}

private void drawFunction(Graphics g, String function) {
    Graphics2D g2d = (Graphics2D) g;
    g2d.setColor(Color.blue);

    double p=0.01; //plotting precision

    for(double x=-5;x<5;x+=p){
        int drawingX1=gx((x));
        int drawingY1=gy(f(x));
        int drawingX2=gx(x+p);
        int drawingY2=gy(f(x+p));
        g2d.drawLine(drawingX1, drawingY1, drawingX2, drawingY2);

    }

}

private double f(double x){
    return x*x;
}

private int gx(double x){
    return (int) ((x+5)*(w/10));
}

private int gy(double y){
    return (int) (h-(y+5)*(h/10));
}

public void setEquation(String equ){
    equation=equ;
}

public void paintComponent(Graphics g) {

    super.paintComponent(g);
    initializeGrid(g);
    drawFunction(g,"Function");
}

public void mouseClicked(MouseEvent e) {
    if(clicks<3){
        MainUI.points[clicks][0] = e.getX();
        MainUI.points[clicks][1] = e.getY();
        System.out.println(e.getX()+","+e.getY());
        System.out.println(MainUI.points[clicks]   [0]+","+MainUI.points[clicks][1]);
        clicks++;
    }
}

public void mouseEntered(MouseEvent e) {
    //not needed
}

public void mouseExited(MouseEvent arg0) {
    //not needed
}

public void mousePressed(MouseEvent arg0) {
    //not needed        
}

public void mouseReleased(MouseEvent arg0) {
    //not needed    
}

public void mouseMoved(MouseEvent e) {
    System.out.println(e.getX()+","+e.getY());      
}
}

Thanks in Advance

Answer 1

MouseListener does not have a mouseMoved method.

You have to add the declaration that you are going to also implement the Mouse Motion Listener interface:

public class drawArea extends JPanel 
    implements MouseListener, MouseMotionListener 

Additionally, you have to add this mouse motion listener in the constructor

this.addMouseMotionListener(this);