将多个JPanel添加到JFrame

Question

Been having a hard time adding JPanels to JFrame. Am pretty much new on java, always used C++ I need to do 4 Panels inside one Frame.

Here is my Code, just started today..

package project2;
import javax.swing.JOptionPane;    
import java.awt.FlowLayout;   
import javax.swing.JFrame;    
import javax.swing.JLabel;   
import javax.swing.JPanel;   
import javax.swing.SwingConstants; 
import java.awt.Color;   
import java.awt.GridLayout;   
import java.awt.BorderLayout;   
import javax.swing.*;  
import java.awt.Container;  
import java.awt.Dimension;

public class GUI extends JFrame 
{
    private JPanel Checks; //Panel to Hold Checks
    private JPanel Transactions;
    private JPanel History;
    private JPanel Graphics;
    private JLabel CLabel;


    public GUI()
    {
        super ( "UTB Check-In");
        JPanel Checks = new JPanel(); //set up panel
        CLabel = new JLabel("Label with text");
        Checks.setBackground(Color.red);
        Checks.setLayout( new BoxLayout(Checks,BoxLayout.LINE_AXIS)); 
        add(Checks);


      // JPanel Transactions = new JPanel();
       // Transactions.setToolTipText("Electronic Transactions");
        //Transactions.setBackground(Color.blue);
       // add(Transactions);

    }

}

I was trying to put Transaction and Checks one side from the other with different colors,in this case blue and red it doesnt stay in the middle it those one or the other. One of my Colleagues told me that the BoxLayout(or any layout) needed to be implemented with the size..something to that extend. am not really sure I been reading http://docs.oracle.com/javase/tutorial/uiswing/layout/box.html

But I still do not get it completely. If somebody can help me out thanks!

Answer 1

Your code fail cause you are adding directly to the JFrame which have by default BorderLayout . You are setting BoxLayout to the wrong panel. You have to setLayout() to the top component(jframe) that you are adding or as i prefer adding to a jpanel rather than directly to the jframe to acomplish what you want to do.

Example:

public GUI()
{
    super ( "UTB Check-In");

    JPanel parent = new JPanel();
    parent.setLayout(new BoxLayout(parent,BoxLayout.LINE_AXIS));
    add(parent);

    JPanel Checks = new JPanel(); //set up panel
    CLabel = new JLabel("Label with text");
    Checks.setBackground(Color.red);
    parent.add(Checks);


   JPanel Transactions = new JPanel();
   Transactions.setToolTipText("Electronic Transactions");
   Transactions.setBackground(Color.blue);
   parent.add(Transactions);

}

By the way, in Java variables starts with lowerCase as a code convention.