ComboDemo.java

package forms;

import com.bulenkov.darcula.DarculaLaf;

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

/**
 * Combo box demo. Created by sasha on 12/02/16.
 */
public class ComboDemo {
    public static void main(String[] args) throws UnsupportedLookAndFeelException {
        UIManager.setLookAndFeel(new DarculaLaf());
        JFrame f = new JFrame("Combo boxes");
        f.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        Container contentPane = f.getContentPane();

        JLabel label = new JLabel();
        JComboBox comboBox = new JComboBox();
        JTextField textField = new JTextField();
        JComboBox comboBox2 = new JComboBox();
        JButton button = new JButton();
        JComboBox comboBox3 = new JComboBox();
        JTextArea textArea = new JTextArea();
        JComboBox comboBox4 = new JComboBox();

        label.setText("label");
        comboBox.setModel(new DefaultComboBoxModel(new String[]{"Item 1", "Item 2", "Item 3", "Item 4"}));
        textField.setText("textfield");
        comboBox2.setModel(new DefaultComboBoxModel(new String[]{"Item 1", "Item 2", "Item 3", "Item 4"}));
        button.setText("button");
        comboBox3.setModel(new DefaultComboBoxModel(new String[]{"Item 1", "Item 2", "Item 3", "Item 4"}));
        textArea.setRows(5);
        textArea.setColumns(10);
        textArea.setText("textArea\nother text\nanother text");
        comboBox4.setModel(new DefaultComboBoxModel(new String[] { "Item 1", "Item 2", "Item 3", "Item 4" }));
        GroupLayout layout = new GroupLayout(contentPane);
        contentPane.setLayout(layout);
        layout.setHorizontalGroup(
                layout.createParallelGroup(GroupLayout.Alignment.LEADING)
                        .addGroup(layout.createSequentialGroup()
                                .addContainerGap()
                                .addGroup(layout.createParallelGroup(GroupLayout.Alignment.LEADING)
                                        .addGroup(layout.createSequentialGroup()
                                                .addComponent(label)
                                                .addPreferredGap(LayoutStyle.ComponentPlacement.RELATED)
                                                .addComponent(comboBox, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE))
                                        .addGroup(layout.createSequentialGroup()
                                                .addComponent(textField, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
                                                .addPreferredGap(LayoutStyle.ComponentPlacement.RELATED)
                                                .addComponent(comboBox2, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE))
                                        .addGroup(layout.createSequentialGroup()
                                                .addComponent(button)
                                                .addPreferredGap(LayoutStyle.ComponentPlacement.RELATED)
                                                .addComponent(comboBox3, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE))
                                        .addGroup(layout.createSequentialGroup()
                                                .addComponent(textArea, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
                                                .addPreferredGap(LayoutStyle.ComponentPlacement.RELATED)
                                                .addComponent(comboBox4, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)))
                                .addContainerGap(GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
        );
        layout.setVerticalGroup(
                layout.createParallelGroup(GroupLayout.Alignment.LEADING)
                        .addGroup(layout.createSequentialGroup()
                                .addContainerGap()
                                .addGroup(layout.createParallelGroup(GroupLayout.Alignment.BASELINE)
                                        .addComponent(label)
                                        .addComponent(comboBox, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE))
                                .addPreferredGap(LayoutStyle.ComponentPlacement.RELATED)
                                .addGroup(layout.createParallelGroup(GroupLayout.Alignment.BASELINE)
                                        .addComponent(textField, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
                                        .addComponent(comboBox2, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE))
                                .addPreferredGap(LayoutStyle.ComponentPlacement.RELATED)
                                .addGroup(layout.createParallelGroup(GroupLayout.Alignment.BASELINE)
                                        .addComponent(button)
                                        .addComponent(comboBox3, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE))
                                .addPreferredGap(LayoutStyle.ComponentPlacement.RELATED)
                                .addGroup(layout.createParallelGroup(GroupLayout.Alignment.BASELINE)
                                        .addComponent(textArea, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
                                        .addComponent(comboBox4, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE))
                                .addContainerGap(GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
        );
        f.pack();
        f.setVisible(true);
        System.out.printf("comboBox baseline %d%n",comboBox.getBaseline(comboBox.getWidth(), comboBox3.getHeight()));
        System.out.printf("comboBox baseline resize behaviour %s%n", comboBox.getBaselineResizeBehavior());
    }

}