java GridBagLayout anchor

Question

Learing GridBagLayout, il problema è che l'etichetta del nome e la combox non vengono visualizzati nella parte superiore del pannello, ma ho impostato l'ancoraggio su NORD. Perché ?

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

import javax.swing.JComboBox; 
import javax.swing.JFrame; 
import javax.swing.JLabel; 
import javax.swing.JPanel; 
import javax.swing.WindowConstants; 

public class Test2 {  
    public Test2() { 
     JFrame frame = new JFrame(); 
     frame.setTitle("test"); 
     frame.getContentPane().setLayout(new GridLayout(1,2)); 
     frame.setSize(800, 600); 

     JPanel panel1 = new JPanel(); 
     panel1.setLayout(new GridBagLayout()); 

     JLabel label = new JLabel("name"); 
     GridBagConstraints gridBagConstraints = new GridBagConstraints(); 
     gridBagConstraints.anchor = GridBagConstraints.NORTH; 
     gridBagConstraints.weightx = 0.0; 
     gridBagConstraints.weighty = 0.0; 
     gridBagConstraints.gridx = 0; 
     gridBagConstraints.gridy = 0; 
     panel1.add(label, gridBagConstraints); 

     String[] petStrings = { "Bird", "Cat", "Dog", "Rabbit", "Pig" }; 
     JComboBox petList = new JComboBox(petStrings); 
     gridBagConstraints = new GridBagConstraints(); 
     gridBagConstraints.anchor = GridBagConstraints.NORTH; 
     gridBagConstraints.fill = GridBagConstraints.HORIZONTAL; 
     gridBagConstraints.weightx = 1.0; 
     gridBagConstraints.weighty = 0.0; 
     gridBagConstraints.gridx = 1; 
     gridBagConstraints.gridy = 0; 
     panel1.add(petList, gridBagConstraints);  

     frame.getContentPane().add(panel1); 
     frame.getContentPane().add(new JPanel());  

     frame.setVisible(true); 
     frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);  
    } 

    public static void main(String[] args) { 
     new Test2(); 
    } 
} 

Answer 1

devi cambiare

gridBagConstraints.weighty = 0.0; 

a

gridBagConstraints.weighty = 1.0; 

altrimenti l'area riservata per il componente è dimagrito alle dimensioni del componente, e non importa in quale direzione di "ancorare" il componente.

Il risultato dopo aver cambiato il weighty è la seguente: