How to move an Oval to the coordinates of the mouseClick?

I am trying to build a little program in Java OOP, that will display an oval that changes its position to mouse click coordinates. However, as I am a beginner I dont know how to finish it.

Does anyone know what is wrong on my program?

public class OvalWindow

JFrame window;
int windowWidth = 500;
int windowHeight = 500;

OvalPanel panel;

public void run()
//Set a window
window = new JFrame("Oval moving");
window.setVisible(true);
window.setSize(windowWidth, windowHeight);
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

//Create a panel and add it to the window
panel = new OvalPanel();
window.setContentPane(panel);

//Change the location on mouse input
panel.addMouseListener(new OvalMouseClick(panel));




public static void main(String args)
OvalWindow oWndow = new OvalWindow();
oWndow.run();





File: Oval.java
Create an Oval class

public class Oval

private int diameter;
private int x;
private int y;
private Color color;

public Oval(int x, int y, int diameter, Color color)
this.x = x;
this.y = y;
this.diameter = diameter;
this.color = color;


public int getX()
return x;

public int getY()
return y;

public int getDiameter()
return diameter;

public Color getColor()
return color;


/*
* Draw the oval
*/
public void draw(Graphics g)
g.fillOval(x, y, diameter, diameter);
g.setColor(color);





File: OvalPanel.java
This class add objects ovals to the screen.
Also, sets the initial position of the oval

public class OvalPanel extends JPanel
Oval oval;

public void addOval(Oval oval)
oval = new Oval(100, 100, 50, Color.BLACK);
this.repaint();


public void paintComponent(Graphics g)
oval.draw(g);






File: OvalMouseClick.java
This class add a new oval to the screen, at the same position as the mouse clicked coordinates.

public class OvalMouseClick extends MouseAdapter
OvalPanel panel;

public OvalMouseClick(OvalPanel panel)
this.panel = panel;



@Override
public void mouseClicked(MouseEvent e)
panel.addOval(new Oval(e.getX(), e.getY(), 50, Color.BLUE));






Oval.draw()

OvalPanel.paintComponent()

3 Answers
3

Write a custom paintComponent() method to make your OvalPanel actually display something. If you added components to it, they would be displayed automatically, but your Oval class is not a component (in the UI sense) so you'll need to explicitly write the code to display them.

paintComponent()

OvalPanel

Oval

@Override
public void paintComponent(Graphics g)
for(Oval o : ovals)
o.draw(g);



I also recommend reading the Swing trail at https://docs.oracle.com/javase/tutorial/uiswing/ because you can't just "guess" how things work. Swing is complex, and you need to understand what it does. Then you'll realize that draw(Graphics g) and paintComponent(Graphics g) are more than similar methods with a different name.

draw(Graphics g)

paintComponent(Graphics g)

Oval

OvalPanel

Color

In case someone is looking for the answer. Here is my solution:

I have modified the file: OvalWindow.java

public class OvalWindow

JFrame window;
OvalPanel panel;

int windowWidth = 500;
int windowHeight = 500;

/**
* Run the program
*/
public void run()
// Set a window
window = new JFrame("Oval moving");
window.setVisible(true);
window.setSize(windowWidth, windowHeight);
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

// Create a panel and add it to the window
panel = new OvalPanel();
window.add(panel, BorderLayout.CENTER);

panel.addMouseListener(new MouseAdapter()
public void mouseClicked(MouseEvent e)
panel.moveToCoord(e);

);



public static void main(String args)
OvalWindow oWndow = new OvalWindow();
oWndow.run();





I have also significantly modified the file: OvalPanel.java

public class OvalPanel extends JPanel
Oval oval;
int x = 50;
int y = 10;
int diameter = 50;
Color color = Color.BLUE;

public void moveToCoord(MouseEvent e)
x = e.getX() - diameter / 2;
y = e.getY() - diameter / 2;
repaint();



@Override
public void paintComponent(Graphics g)
super.paintComponent(g);
oval = new Oval(x, y, diameter, color);
oval.draw(g);






On the file: Oval.java was only a small change:

public void draw(Graphics g)
g.setColor(color);
g.fillOval(x, y, diameter, diameter);




The file: OvalMouseClick.java was removed.

Just let the class „OvalMouseClick“ implement the interface MouseListener. If you want to do something when the mouse moves, just let the class also implement the interface „MouseMotionListener“. For the MouseWheel you can use the interface „MouseWheelListener“.

MouseAdapter

MouseMotionListener

MouseWheelListener

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