When I press the free button I can draw in the bottom pane but when I press the rectangle button I can draw a rectangle in the panel but I can also draw anything in the same time. My goal is that when I press one of the functions I want the other to stop functioning.
public class MyFrame extends JFrame implements ActionListener, MouseListener , MouseMotionListener{
JPanel top;
JPanel bottom ;
JButton btn1,btn4;
int freebtn,rectanglebtn;
Graphics g;
public MyFrame(){
this.setTitle("car");
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setSize(700,700);
this.setLayout(null);
this.setResizable(false);
top = new JPanel();
bottom = new JPanel();
top.setBounds(0, 0, 700, 100);
top.setBackground(Color.blue);
bottom.setBounds(0, 100, 700, 600);
bottom.setBackground(Color.white);
btn1 = new JButton("free");
btn4 = new JButton("rectangle");
btn1.addActionListener(this);
btn4.addActionListener(this);
top.add(btn1);top.add(btn4);
this.add(top);
this.add(bottom);
bottom.addMouseMotionListener(this);
bottom.addMouseListener(this);
this.setVisible(true);
g=bottom.getGraphics();
}
// action listener-------------------------------
@Override
public void actionPerformed(ActionEvent e) {
// TODO Auto-generated method stub
if(e.getActionCommand() =="free") {
System.out.println("free button");
freebtn=11;
}
else if(e.getActionCommand() =="rectangle") {
System.out.println("rectangle button");
rectanglebtn=12;
}
}
// mouse listener-----------------------------
@Override
public void mouseClicked(MouseEvent e) {
// TODO Auto-generated method stub
}
@Override
public void mousePressed(MouseEvent e) {
// TODO Auto-generated method stub
System.out.println(rectanglebtn);
if(rectanglebtn==12) {
g.setColor(Color.BLUE);
g.drawRect(e.getX(),e.getY(), 100, 50);
}
}
@Override
public void mouseReleased(MouseEvent e) {
// TODO Auto-generated method stub
}
@Override
public void mouseEntered(MouseEvent e) {
// TODO Auto-generated method stub
}
@Override
public void mouseExited(MouseEvent e) {
// TODO Auto-generated method stub
}
// mouse motion listener---------------------------
@Override
public void mouseDragged(MouseEvent e) {
// TODO Auto-generated method stub
System.out.println(freebtn);
if(freebtn==11) {
g.setColor(Color.BLUE);
g.fillOval(e.getX(),e.getY(),20,20);
}
}
@Override
public void mouseMoved(MouseEvent e) {
// TODO Auto-generated method stub
}
}
I tried to to set one of them to null when I'm using the other but it didnt work
CodePudding user response：
Let's start with...
@Override
public void actionPerformed(ActionEvent e) {
// TODO Auto-generated method stub
if(e.getActionCommand() =="free") {
System.out.println("free button");
freebtn=11;
}
else if(e.getActionCommand() =="rectangle") {
System.out.println("rectangle button");
rectanglebtn=12;
}
}
Apart from the fact that you are using e.getActionCommand() =="rectangle" instead of "rectangle".equals(e.getActionCommand()) (see How do I compare strings in Java?, for more details) , once either freebtn or rectanglebtn are actioned, the values they set never change.
So, for example, if I press the rectangle button, rectanglebtn is set to 12. If I then press free button, rectanglebtn is still 12
Instead of using two different (and somewhat unrelated) variables, you should be using a single "state" variable. Now, if you have more than two states, I would use a enum, for example...
enum State {
FREE, RECTANGLE, CIRCLE
}
And then update the action handler to something like...
private State state = null;
// action listener-------------------------------
@Override
public void actionPerformed(ActionEvent e) {
// TODO Auto-generated method stub
if ("free".equals(e.getActionCommand())) {
System.out.println("free button");
state = State.FREE;
} else if ("rectangle".equals(e.getActionCommand())) {
System.out.println("rectangle button");
state = State.RECTANGLE;
}
}
Now, whenever either button is actioned, the state is changed to a single state.
Then your mouse listener begins to look something more like...
@Override
public void mousePressed(MouseEvent e) {
// TODO Auto-generated method stub
System.out.println(state);
if (state == State.RECTANGLE) {
g.setColor(Color.BLUE);
g.drawRect(e.getX(), e.getY(), 100, 50);
}
}
// mouse motion listener---------------------------
@Override
public void mouseDragged(MouseEvent e) {
// TODO Auto-generated method stub
System.out.println(state);
if (state == State.FREE) {
g.setColor(Color.BLUE);
g.fillOval(e.getX(), e.getY(), 20, 20);
}
}
and there is no way that they could become cross wired.
Now, onto the "other" issues... g = bottom.getGraphics(); is NOT how custom painting works. At best, this will return a "snapshot" of what was last painted and at worst, it will return null.
You need to look at Painting in AWT and Swing and Performing Custom Painting to get a better understanding of how painting in Swing works and how you should work with it.