Question

I have searched for this problem and haven’t found anything close. I will try to be specific and post code however this is a large program so I can’t post all the code. The problem in general is this: A JButton on one panel causes components on another panel to shift at first click. This only occurs when there is an action listener added to the button. (clicking the button without an action listener doe noting (obviously)). The problem is that the action listener i add only changes the button background, text, and size (to fit new text).

Here is the action listener as of right now. login is the JButton:

private class LoginListener implements ActionListener{

  public void actionPerformed(ActionEvent e){

    loggedIn = !loggedIn;

    if(loggedIn){
      login.setText("Logout");
      login.setBackground(Constants.RED);
    }
    else{
      login.setText("Login");
      login.setBackground(Constants.UPPER_BOUNDARY);
    }

    login.setSize(login.getPreferredSize());
  }
}

The setup is this. The action listener is a subclass of the loginPanel where the login button is located. That loginPanel is added to the main JFrame at the upper 1/4 of the frame. The lower 3/4 of the main JFrame is mainPanel which has other swing components. The loginPanel and mainPanel do not share components or variables or really know of each other’s existence (as far as I have coded). Yet when this actionlistener above is added to the login button components in the mainPanel shift from their positions to other positions. The only happens at first click and then they stay where they are at (not where i want them).

Other factors:
– I use absolute positioning (sorry if you don’t like it but I like it better)
– I am using a SynthLookAndFeel but have never had this issue with this look and feel before.

Thanks

Answer 1

Other factors: – I use absolute positioning (sorry if you don’t like it but I like it better)

There’s nothing to be sorry about, and the solution is simple: Don’t use absolute positioning, but instead learn about and use the layout managers to there full abilities. One of the reasons to use them is to avoid pernicious bugs like this one. It’s quite possible that your code is in fact using a component’s default layout manager even now without you knowing about it. You can find out more about them here. One of the keys to using them well is to nest them by using nested JPanels, each using its own layout manager. Then they can do the heavy layout lifting for you automatically.