Java JFrame / Swing对齐

Question

我是新手，目前正在学习JFrame，但我的ComboBox，复选框和按钮的对齐方式遇到问题。 侦听器尚未连接起来，这只是测试是否正确对齐。 我的问题是为什么对齐功能似乎不起作用？ 我希望组合框位于顶部，中间是复选框，底部是按钮。

import java.awt.FlowLayout;
import java.awt.Font;
import java.awt.event.ItemListener;
import java.awt.event.ItemEvent;
import javax.swing.JFrame;
import javax.swing.JTextField;
import javax.swing.JCheckBox;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.SwingConstants;

public class CheckBoxFrame extends JFrame 
{

private final JComboBox<String> colorComboBox; 
private final JCheckBox backgroundColorCheckBox; 
private final JCheckBox foregroundColorCheckBox; 
private final JButton okButton;
private final JButton cancelButton;

private static final String[] color =
{"Red", "Blue", "Green", "Purple"};

public CheckBoxFrame()
{
  super("ColorSelect");
  setLayout(new FlowLayout());


  colorComboBox = new JComboBox<String>(color);
  colorComboBox.setAlignmentX(SwingConstants.TOP);
  add(colorComboBox);


  backgroundColorCheckBox = new JCheckBox("Background"); 
  foregroundColorCheckBox = new JCheckBox("Foreground"); 
  foregroundColorCheckBox.setVerticalAlignment(SwingConstants.CENTER);
  backgroundColorCheckBox.setVerticalAlignment(SwingConstants.CENTER);
  add(backgroundColorCheckBox); // add bold checkbox to JFrame
  add(foregroundColorCheckBox); // add italic checkbox to JFrame

  okButton = new JButton("Ok");
  cancelButton = new JButton("Cancel");
  okButton.setVerticalAlignment(SwingConstants.BOTTOM);
  cancelButton.setVerticalAlignment(SwingConstants.BOTTOM);
  add(okButton);
  add(cancelButton);


  // register listeners for JCheckBoxes
  CheckBoxHandler handler = new CheckBoxHandler();
  backgroundColorCheckBox.addItemListener(handler);
  foregroundColorCheckBox.addItemListener(handler);
  } 


private class CheckBoxHandler implements ItemListener 
{
  // respond to checkbox events
  @Override
  public void itemStateChanged(ItemEvent event)
  {

  } 
 }
} // end class CheckBoxFrame

Answer 1

从JavaDocs获得setVerticalAlignment

设置图标和文本的垂直对齐方式。

这将更改在组件上下文内布置icon和text属性的方式。

setVerticalAlignment不会影响组件在容器中的布局方式。

要更改组件在容器中的布局方式，您将需要更改布局管理器，请参阅课程：在容器中布局组件

根据您的要求，有多种方法可以实现它。

您可以使用GridLayout ，将单个行的所有组件包装在自己的JPanel并将此面板添加到主容器中。

您还可以使用GridBagLayout ，它虽然更复杂，但也更灵活

Answer 2

• 请参阅Java Swing布局管理器上的官方文档： https : //docs.oracle.com/javase/tutorial/uiswing/layout/visual.html 。

• FlowLayout是较为基本的布局管理器之一，因此建议您查看GridBagLayout 。

• 尝试这个：

import java.awt.FlowLayout;
import java.awt.Font;
import java.awt.event.ItemListener;
import java.awt.event.ItemEvent;
import javax.swing.JFrame;
import javax.swing.JTextField;
import javax.swing.JCheckBox;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.SwingConstants;

public class CheckBoxFrame extends JFrame 
{

private final JComboBox<String> colorComboBox; 
private final JCheckBox backgroundColorCheckBox; 
private final JCheckBox foregroundColorCheckBox; 
private final JButton okButton;
private final JButton cancelButton;

private static final String[] color = {"Red", "Blue", "Green", "Purple"};

public CheckBoxFrame()
{
  super("ColorSelect");
  setLayout(new GridBagLayout());

  GridBagConstraints c = new GridBagConstraints();
  colorComboBox = new JComboBox<String>(color);
  c.fill = GridBagConstraints.HORIZONTAL;
  c.gridx = 0;
  c.gridy = 0;
  c.gridwidth = 2;
  add(colorComboBox, c);


  backgroundColorCheckBox = new JCheckBox("Background"); 
  c.fill = GridBagConstraints.HORIZONTAL;
  c.gridx = 0;
  c.gridy = 1;
  c.gridwidth = 1;
  add(backgroundColorCheckBox, c); // add bold checkbox to JFrame

  foregroundColorCheckBox = new JCheckBox("Foreground");
  c.fill = GridBagConstraints.HORIZONTAL;
  c.gridx = 1;
  c.gridy = 1;
  c.gridwidth = 1;
  add(foregroundColorCheckBox, c); // add italic checkbox to JFrame

  okButton = new JButton("Ok");
  c.fill = GridBagConstraints.HORIZONTAL;
  c.gridx = 0;
  c.gridy = 2;
  c.gridwidth = 1;
  add(okButton, c);

  cancelButton = new JButton("Cancel");
  c.fill = GridBagConstraints.HORIZONTAL;
  c.gridx = 1;
  c.gridy = 2;
  c.gridwidth = 1;
  add(cancelButton, c);


  // register listeners for JCheckBoxes
  CheckBoxHandler handler = new CheckBoxHandler();
  backgroundColorCheckBox.addItemListener(handler);
  foregroundColorCheckBox.addItemListener(handler);
  } 


private class CheckBoxHandler implements ItemListener 
{
  // respond to checkbox events
  @Override
  public void itemStateChanged(ItemEvent event)
  {

  } 
 }
} // end class CheckBoxFrame