Java GridBagLayout定位

Question

我正在尝试使用 GridBagLayout 创建一个窗口，这是我的代码:

   import java.awt.FlowLayout;
   import java.awt.GridBagConstraints;
   import java.awt.GridBagLayout;
   import java.awt.event.ActionEvent;
   import java.awt.event.ActionListener;

   import javax.swing.JButton;
   import javax.swing.JFrame;
   import javax.swing.JPanel;
   import javax.swing.JScrollPane;
   import javax.swing.JTextArea;

   public class ReadMessage extends JFrame implements ActionListener
   {
JButton Last;
JButton Delete;
JButton Store;
JButton Next;
JTextArea MessageBox;

public ReadMessage()
{
    setLayout(new FlowLayout());
    JPanel Panel = new JPanel();
    add(Panel);
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    Panel.setLayout(new GridBagLayout());
    GridBagConstraints c = new GridBagConstraints();


    MessageBox = new JTextArea();
    MessageBox.setEditable(false);
    JScrollPane scrollPane = new JScrollPane(MessageBox, JScrollPane.VERTICAL_SCROLLBAR_ALWAYS,
            JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
    MessageBox.setLineWrap(true);
    c.gridx = 0;
    c.gridy = 0;
    c.gridwidth = 4;
    c.weightx = 0.0;
    c.ipady = 300;
    c.ipadx = 300;
    Panel.add(scrollPane, c);


    Last = new JButton("Last");
    c.gridx = 0;
    c.gridy = 1;
    c.ipady = 0; 
    c.weightx = 0.5;
    Panel.add(Last, c);
    Last.addActionListener(this);

    Delete = new JButton("Delete");
    c.gridx = 1;
    c.gridy = 1;
    c.ipady = 0; 
    c.weightx = 0.5;
    Panel.add(Delete, c);
    Delete.addActionListener(this);

    Store = new JButton("Store");
    c.gridx = 2;
    c.gridy = 1;
    c.ipady = 0; 
    c.weightx = 0.5;
    Panel.add(Store, c);
    Store.addActionListener(this);

    Next = new JButton("Next");
    c.gridx = 3;
    c.gridy = 1;
    c.ipady = 0; 
    c.weightx = 0.5;
    Panel.add(Next, c);
    Next.addActionListener(this);

}



}

结果是这样的

我真正想要的就是这样

我知道我做错了，但我不知道我到底做错了什么，我阅读了oracle上的文档，但找不到任何东西，你能指出我做错了什么，以及如何修复它吗？非常感谢

Answer 1

所有按钮的网格宽度均为 4，而不是 1。