how to place Panel into Frame

[vivek modi]

Hi Everybody !! I am new to Swing and am working on a GUI based Elevator Simulation System. I am using Frame on which I am trying to put a Panel. But the panel does not set to the size I want it to even if I use setSize() method. I am posting the code .Could anyone please help me.

Thanks !!

 

 

package elevator;
 
import javax.swing.*;
import java.awt.*;
 
public class Controller {
    
    public static void main(String args[])
    {
        
      Container cpane;
      JFrame frame = new JFrame("ELEVATOR");
      cpane = frame.getContentPane();
      Lift1Panel lp1 = new Lift1Panel();
      frame.setVisible(true);
      frame.setSize(1300,800);
      frame.add(lp1);
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
    
    }
    
    
}     
 
package elevator;
 
import javax.swing.*;
import java.awt.*;
 

 
public class Lift1Panel extends JPanel {
    
    
    public Lift1Panel() 
    {
    
     setSize(200,200);
        
    }
    
 
    public void paintComponent(Graphics g)
    {
        
     super.paintComponent(g);
        
     Graphics2D g2d = (Graphics2D)g;
     g2d.setColor(Color.WHITE); 
     g2d.drawRect(10,10,100,100);   
    
    }
 

 

}
 

[Maneesh Godbole]

Originally posted by vivek modi:
Hi Everybody !! I am new to Swing and am working on a GUI based Elevator Simulation System. I am using Frame on which I am trying to put a Panel. But the panel does not set to the size I want it to even if I use setSize() method. I am posting the code .Could anyone please help me.

Thanks !!

To achieve the desired result, you need to change two things:

1)The content pane has a BorderLayout by default. So when you say

frame.add(lp1);

the lp1 is set to the Center which ignores the panel dimension. So you need to call

cpane.setLayout(new FlowLayout())

before adding the components, which will start respecting the panel dimensions

2)Use

panel.setPreferredSize(new Dimension(200,200));

instead of setSize. Whenever a container lays out the components inside, it queries for the preferred size.

It is also a good practise to call the setVisible() on the frame as the last statement. Setting the frame dimensions, adding the components should be done before you call the setVisible.

Even thought your existing code works right now, what is happening is this:
The frame.setVisible() is called. Since you have not provided any dimensions, the default 0,0 dimensions are used. Then the components are set. Since the contained components are changed, the repaint is called, which again calls the code to resize the window and display the laid out components.

So in a nutshell, the frame is repainted twice unnecessarily.

[vivek modi]

Hi Maneesh !! Your post solved my problem. Now my panel is getting displayed on the frame.Thanks !! But I have one more query. I want to display the panel at my desired location and using method setLocation() it does not work.
Is there any other way ?

[Maneesh Godbole]

Originally posted by vivek modi:
I want to display the panel at my desired location and using method setLocation() it does not work.
Is there any other way ?

Why do you want to specify the exact location? Have you considered what will happen if the user resizes the frame or the user is running some different screen resolution? The LayoutManagers are designed to handle all these.
Even then, if your requirement dictates that you specify a location, this is what you need to do.

1) Set the layout of the content pane to null by calling getContentPane.setLayout(null);
2) Add the panel to the content pane.
3) Define the bounds of the panel by calling panel.setBounds(int x, int y, int width, int height) where x,y are the location and the width and height are the dimensions of the panel.

Please note the step#2 should be called before step#3 , else it wont work.

Best of luck.
[ November 19, 2007: Message edited by: Maneesh Godbole ]

[vivek modi]

Thanks Maneesh !! It worked

[akshay gupta]

Maneesh Godbole wrote:

Originally posted by vivek modi:
I want to display the panel at my desired location and using method setLocation() it does not work.
Is there any other way ?

Why do you want to specify the exact location? Have you considered what will happen if the user resizes the frame or the user is running some different screen resolution? The LayoutManagers are designed to handle all these.
Even then, if your requirement dictates that you specify a location, this is what you need to do.

1) Set the layout of the content pane to null by calling getContentPane.setLayout(null);
2) Add the panel to the content pane.
3) Define the bounds of the panel by calling panel.setBounds(int x, int y, int width, int height) where x,y are the location and the width and height are the dimensions of the panel.

Please note the step#2 should be called before step#3 , else it wont work.

Best of luck.
[ November 19, 2007: Message edited by: Maneesh Godbole ]

Thank you ....it helped me a lot..

[Darryl Burke]

Maneesh Godbole wrote:Please note the step#2 should be called before step#3 , else it wont work.

Not so. The order isn't critical.

import java.awt.Color;
import javax.swing.*;

public class BoundsBefore {

  public static void main(String[] args) {
    SwingUtilities.invokeLater(new Runnable() {

      @Override
      public void run() {
        new BoundsBefore().makeUI();
      }
    });
  }

  public void makeUI() {
    JPanel panel1 = new JPanel();
    panel1.setBackground(Color.red);
    panel1.setBounds(50, 50, 100, 100);

    JPanel panel2 = new JPanel();
    panel2.setBackground(Color.blue);
    panel2.setBounds(200, 200, 100, 100);

    JFrame frame = new JFrame();
    frame.setLayout(null);
    frame.add(panel1);
    frame.add(panel2);

    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setSize(400, 400);
    frame.setLocationRelativeTo(null);
    frame.setVisible(true);
  }
}

Note that when using a layout manager, it's important to set the layout before adding the components.

[pratik maru]

Maneesh Godbole wrote:

Originally posted by vivek modi:
I want to display the panel at my desired location and using method setLocation() it does not work.
Is there any other way ?

Why do you want to specify the exact location? Have you considered what will happen if the user resizes the frame or the user is running some different screen resolution? The LayoutManagers are designed to handle all these.
Even then, if your requirement dictates that you specify a location, this is what you need to do.

1) Set the layout of the content pane to null by calling getContentPane.setLayout(null);
2) Add the panel to the content pane.
3) Define the bounds of the panel by calling panel.setBounds(int x, int y, int width, int height) where x,y are the location and the width and height are the dimensions of the panel.

Please note the step#2 should be called before step#3 , else it wont work.

Best of luck.
[ November 19, 2007: Message edited by: Maneesh Godbole ]

hey Manish it will be a great help if you can tell me how make my swing application program work in different resolution systems
thanks

[Darryl Burke]

pratik maru wrote:how make my swing application program work in different resolution systems

Use an appropriate layout manager or combination of nested layouts and pack() the window that displays the GUI.

[pratik maru]

Darryl Burke wrote:

pratik maru wrote:how make my swing application program work in different resolution systems

Use an appropriate layout manager or combination of nested layouts and pack() the window that displays the GUI.

by appropriate layout manager you mean which one and can you give me an example

[Hitesh P Patel]

by appropriate layout manager you mean which one

It depends on your design to choose the appropriate layout

can you give me an example

Read the section from the Swing tutorial on How to Use Various Layout Managers