如何使用GridBagLayout在多列上拉伸组件？

我一直在学习 Java Swing 中的布局，目前正在制作一个简单的计算器。我将使用文本字段进行输入/输出，我想将其拉伸到 2 列（我总共使用了三列），但是当我尝试拉伸它时，它会调整第一列中项目的大小。这是代码和屏幕截图。

应用截图：

import java.awt.Font;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.GridLayout;
import java.awt.Insets;

import javax.swing.*;

public class Calculator extends JFrame{

    JButton but1, but2, but3, but4, but5, but6,
        but7, but8, but9, but0, butPlus, butMinus,
        clearAll;

    JTextField textResult;

    int num1, num2;

    public static void main(String[] args){
    
        new Calculator();
        
    }

    public Calculator(){
            
        this.setSize(400,400);
        this.setLocationRelativeTo(null);
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.setTitle("Calculator");
    
        JPanel thePanel = new JPanel();
    
        thePanel.setLayout(new GridBagLayout());
    
        GridBagConstraints gridConstraints = new GridBagConstraints();
    
        gridConstraints.gridx = 0;
        gridConstraints.gridy = 0;
        gridConstraints.gridwidth = 1;
        gridConstraints.gridheight = 1;
        gridConstraints.weightx = 50;
        gridConstraints.weighty = 100;
        gridConstraints.insets = new Insets(5, 5, 5, 5);
        gridConstraints.anchor = GridBagConstraints.CENTER;
        gridConstraints.fill = GridBagConstraints.BOTH;
    
        textResult = new JTextField("0", 20);
    
        Font font = new Font("Helvetica", Font.PLAIN, 18);
        textResult.setFont(font);
    
        but1 = new JButton("1");
        but2 = new JButton("2");
        but3 = new JButton("3");
        but4 = new JButton("4");
        but5 = new JButton("5");
        but6 = new JButton("6");
        but7 = new JButton("7");
        but8 = new JButton("8");
        but9 = new JButton("9");
        butPlus = new JButton("+");
        but0 = new JButton("0");
        butMinus = new JButton("-");
        clearAll = new JButton("C");
    
        thePanel.add(clearAll, gridConstraints);
        gridConstraints.gridx = 1;
        gridConstraints.gridwidth = 2;
    
        thePanel.add(textResult, gridConstraints);
        gridConstraints.gridwidth = 1;
        gridConstraints.gridx = 0;
        gridConstraints.gridy = 1;
        thePanel.add(but1, gridConstraints);
        gridConstraints.gridx = 1;
        thePanel.add(but2, gridConstraints);
        gridConstraints.gridx = 2;
        thePanel.add(but3, gridConstraints);
        gridConstraints.gridx = 0;
        gridConstraints.gridy = 2;
        thePanel.add(but4, gridConstraints);
        gridConstraints.gridx = 1;
        thePanel.add(but5, gridConstraints);
        gridConstraints.gridx = 2;
        thePanel.add(but6, gridConstraints);
        gridConstraints.gridx = 0;
        gridConstraints.gridy = 3;
        thePanel.add(but7, gridConstraints);
        gridConstraints.gridx = 1;
        thePanel.add(but8, gridConstraints);
        gridConstraints.gridx = 2;
        thePanel.add(but9, gridConstraints);
        gridConstraints.gridx = 0;
        gridConstraints.gridy = 4;
        thePanel.add(butPlus, gridConstraints);
        gridConstraints.gridx = 1;
        thePanel.add(but0, gridConstraints);
        gridConstraints.gridx = 2;
        thePanel.add(butMinus, gridConstraints);
    
    
        this.add(thePanel);
    
        this.setVisible(true);
    }
}