如何在GridBagLayout中的组件之间放置空格？

Question

在带有BorderLayout的JFrame中，我在窗口底部有一个“控制面板”（带有按钮和东西）。在这个“控制面板”的JPanel中，我想使用GridBagLayout。 这是我现在的结果。

我想在一个3行×8列表来划分的布局。 在这个配置中，“+”符号应该只有一个正方形，所有的按钮都应该填满面板。

的代码是这样的：

buttonsPanel.setLayout(new GridBagLayout()); 
GridBagConstraints c = new GridBagConstraints(); 
c.fill = GridBagConstraints.HORIZONTAL; 

removeCost = new JButton("-"); 
c.gridx = 5; 
c.gridy = 0; 
buttonsPanel.add(removeCost, c); 

addCost = new JButton("+"); 
c.gridx = 7; 
c.gridy = 0; 
buttonsPanel.add(addCost, c); 

text = new JLabel("Incasso"); 
c.gridx = 0; 
c.gridy = 1; 
c.gridwidth = 3; 
buttonsPanel.add(text, c); 

cost = new JTextArea(); 
cost.setBorder(BorderFactory.createLineBorder(Color.black, 1, true)); 
cost.setPreferredSize(new Dimension(80, 18)); 
c.gridx = 5; 
c.gridy = 1; 
c.gridwidth = 3; 
buttonsPanel.add(cost, c); 

cancel = new JButton("Cancella"); 
c.anchor = GridBagConstraints.LINE_START; 
c.fill = GridBagConstraints.HORIZONTAL; 
c.gridx = 0; 
c.gridy = 2; 
c.gridwidth = 3; 
c.insets = new Insets(0, 2, 2, 30); 
buttonsPanel.add(cancel, c); 

enter = new JButton("Accetta"); 
c.anchor = GridBagConstraints.LINE_END; 
c.fill = GridBagConstraints.HORIZONTAL; 
c.gridx = 5; 
c.gridy = 2; 
c.gridwidth = 3; 
c.insets = new Insets(0, 30, 2, 2); 
buttonsPanel.add(enter, c); 

我在做什么错？

Answer 1

每次将其用作add方法的参数时，都需要创建GridBagConstraints（c = new GridBagConstraints）的新实例。

Answer 2

您无法创建GridBagConstrains的新实例。我这样做了。 我执行你的代码。请看截图。

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

public class app { 
public static void main(String[] args) { 
    JFrame frame = new JFrame(); 
    JPanel buttonsPanel = new JPanel(new GridBagLayout()); 
    frame.add(buttonsPanel); 
    // ===================== 
    GridBagConstraints c = new GridBagConstraints(); 
    c.fill = GridBagConstraints.HORIZONTAL; 

    JButton removeCost = new JButton("-"); 
    c.gridx = 5; 
    c.gridy = 0; 
    buttonsPanel.add(removeCost, c); 

    JButton addCost = new JButton("+"); 
    c.gridx = 7; 
    c.gridy = 0; 
    buttonsPanel.add(addCost, c); 

    JLabel text = new JLabel("Incasso"); 
    c.gridx = 0; 
    c.gridy = 1; 
    c.gridwidth = 3; 
    buttonsPanel.add(text, c); 

    JTextArea cost = new JTextArea(); 
    cost.setBorder(BorderFactory.createLineBorder(Color.black, 1, true)); 
    cost.setPreferredSize(new Dimension(80, 18)); 
    c.gridx = 5; 
    c.gridy = 1; 
    c.gridwidth = 3; 
    buttonsPanel.add(cost, c); 

    JButton cancel = new JButton("Cancella"); 
    c.anchor = GridBagConstraints.LINE_START; 
    c.fill = GridBagConstraints.HORIZONTAL; 
    c.gridx = 0; 
    c.gridy = 2; 
    c.gridwidth = 3; 
    c.insets = new Insets(0, 2, 2, 30); 
    buttonsPanel.add(cancel, c); 

    JButton enter = new JButton("Accetta"); 
    c.anchor = GridBagConstraints.LINE_END; 
    c.fill = GridBagConstraints.HORIZONTAL; 
    c.gridx = 5; 
    c.gridy = 2; 
    c.gridwidth = 3; 
    c.insets = new Insets(0, 30, 2, 2); 
    buttonsPanel.add(enter, c); 

    frame.setVisible(true); 
    frame.setLocationRelativeTo(null); 
    frame.setSize(new Dimension(400, 400)); 
} 
} 

您需要拥有此行为吗？