Java GridBagLayout anchor

Question

Learing GridBagLayout, the problem is here: the title label and combox do not appear at the top of the panel, but I set its binding to NORTH. Why?

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

You have to change

 gridBagConstraints.weighty = 0.0; 

to

 gridBagConstraints.weighty = 1.0; 

otherwise, the area reserved for the component will be reduced to the size of the component, and it does not matter in which direction you “snap” the component.

The result after changing the weighty as follows: