Java Swing GridbagLayout Space Izquierda

Question

Estoy atrapado con Java GridbagLayout. Aquí solo queda un problema. Quiero que el panel central ("Testing Label 2") tome todos los espacios verticales que quedan.

¿Cómo lograr esto?

Gracias.

 package com;

import java.awt.Color;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.GridLayout;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.border.LineBorder;
import javax.swing.border.TitledBorder;

public class Test1 {
    private void _panel1(JPanel panel){
        panel.setBorder(new LineBorder(Color.RED));

        panel.setLayout(new GridBagLayout());

        JPanel panel1 = new JPanel();
        panel1.add(new JLabel(" Testing Label 1 "));

        panel1.setBorder(new TitledBorder("P1"));
        GridBagConstraints c = new GridBagConstraints();
        c.fill = GridBagConstraints.HORIZONTAL;
        c.anchor = GridBagConstraints.NORTH;
        c.gridx = 0;
        c.gridy = 0;
        c.weightx = 1.0;
        c.weighty = 0.0;    

        panel.add(panel1, c);

        JPanel panel2 = new JPanel();
        panel2.add(new JLabel(" Testing Label 2"));

        panel2.setBorder(new TitledBorder("P2"));
        c = new GridBagConstraints();   
        c.fill = GridBagConstraints.HORIZONTAL;
        c.anchor = GridBagConstraints.NORTH;
        c.gridx = 0;
        c.gridy = 1;    
        c.weightx = 1.0;
        c.weighty = 1.0;        

        panel.add(panel2, c);

        JPanel panel3 = new JPanel();
        panel3.setBorder(new TitledBorder("P3"));
        c = new GridBagConstraints();   
        c.fill = GridBagConstraints.HORIZONTAL;
        c.anchor = GridBagConstraints.NORTH;
        c.gridx = 0;
        c.gridy = 2;    
        c.weightx = 1.0;
        c.weighty = 0.0;

        panel3.setLayout(new GridLayout(5,1));
        for(int i=0; i<5; i++){
            panel3.add(new JButton("button "+i));
        }

        panel.add(panel3, c);   
    }
    public Test1(){
        JFrame frame = new JFrame();
        frame.setTitle("test 1");
        frame.getContentPane().setLayout(new GridLayout(1,3));

        JPanel panel1 = new JPanel();
        _panel1(panel1);

        JPanel panel2 = new JPanel();
        JPanel panel3 = new JPanel();

        frame.getContentPane().add(panel1);
        frame.getContentPane().add(panel2);
        frame.getContentPane().add(panel3);

        frame.setSize(800, 600);
        frame.setVisible(true);     
    }

    public static void main(String[] args) {
        Test1 t = new Test1();
    }

}

Answer 1

Acabo de cambiar una línea (27):

    final JPanel panel2 = new JPanel();
    panel2.add(new JLabel(" Testing Label 2"));

    panel2.setBorder(new TitledBorder("P2"));
    c = new GridBagConstraints();
    // You have to use BOTH for the panel to take
    // all vertical and horizontal space
    c.fill = GridBagConstraints.BOTH;

Estabas estableciendo la restricción de la cuadrícula para panel2 a HORIZONTAL.

Saludos,

Answer 2

Considere cambiar el campo de relleno de GridbagConstraint a ambos para panel2:

  panel2.setBorder(new TitledBorder("P2"));
  c = new GridBagConstraints();
  c.fill = GridBagConstraints.BOTH; // *****
  c.anchor = GridBagConstraints.NORTH;

O eso o para una solución mucho más simple, solo use un borderLayout: en su lugar:

  panel.setBorder(new LineBorder(Color.RED));

  panel.setLayout(new BorderLayout());

  JPanel panel1 = new JPanel();
  panel1.add(new JLabel(" Testing Label 1 "));

  panel1.setBorder(new TitledBorder("P1"));
  panel.add(panel1, BorderLayout.NORTH);

  JPanel panel2 = new JPanel();
  panel2.add(new JLabel(" Testing Label 2"));

  panel2.setBorder(new TitledBorder("P2"));

  panel.add(panel2, BorderLayout.CENTER);

  JPanel panel3 = new JPanel();
  panel3.setBorder(new TitledBorder("P3"));

  panel3.setLayout(new GridLayout(5, 1));
  for (int i = 0; i < 5; i++) {
     panel3.add(new JButton("button " + i));
  }

  panel.add(panel3, BorderLayout.SOUTH);