Question

用Java做一个简单的计算器

在JFrame框架最上是输入数字的JTextField，怎么使得JTextField的宽度随框架的改变一起改变，而且是恰好在宽度上填充满框架

Answer 1

1. 窗体
   package Calc;
   
   import java.awt.*;
   import java.awt.event.*;
   
   import javax.swing.*;
   
   /**
   *
   * 计算器程序
   *
   */
   public class CalcFrame extends JFrame {
   JButton[] buttons = new JButton[16];// 16个按钮
   
   StringBuffer sb = null;//
   
   JTextField text1 = null;// 计算器结果显示框
   
   String no1 = null;
   
   String sign = null;// 表示+-*/符号
   
   String[] s = { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "+", "-",
     "*", "/", "=", "C" };// 面板上的字符
   
   public CalcFrame() {
    setTitle("计算器");
    setResizable(false);
    setBounds(200, 200, 300, 350);
    setLayout(null);
   
    sb = new StringBuffer();
    text1 = new JTextField();
    text1.setBounds(10, 10, 250, 30);// 设置位置
    text1.setFont(new Font("Arial", Font.PLAIN, 20));// 设置字体
    text1.setForeground(Color.RED);// 设置颜色
    add(text1);
    for (int i = 0; i < s.length; i++) {
   
     buttons[i] = new JButton(s[i]);
     buttons[i].setFont(new Font("Serif", Font.BOLD, 18));
     add(buttons[i]);
    }// 生成面板上的按钮.
   
    buttons[0].setBounds(10, 50, 50, 40);
    buttons[0].addActionListener(new ActionListener() {
   
     public void actionPerformed(ActionEvent e) {
      sb.append(0);
      text1.setText(sb.toString());
     }
   
    });
    buttons[1].setBounds(70, 50, 50, 40);
    buttons[1].addActionListener(new ActionListener() {
   
     public void actionPerformed(ActionEvent e) {
      sb.append(1);
      text1.setText(sb.toString());
     }
   
    });
    buttons[2].setBounds(130, 50, 50, 40);
    buttons[2].addActionListener(new ActionListener() {
   
     public void actionPerformed(ActionEvent e) {
      sb.append(2);
      text1.setText(sb.toString());
     }
   
    });
    buttons[3].setBounds(190, 50, 50, 40);
    buttons[3].addActionListener(new ActionListener() {
   
     public void actionPerformed(ActionEvent e) {
      sb.append(3);
      text1.setText(sb.toString());
     }
   
    });
    buttons[4].setBounds(10, 100, 50, 40);
    buttons[4].addActionListener(new ActionListener() {
   
     public void actionPerformed(ActionEvent e) {
      sb.append(4);
      text1.setText(sb.toString());
     }
   
    });
    buttons[5].setBounds(70, 100, 50, 40);
    buttons[5].addActionListener(new ActionListener() {
   
     public void actionPerformed(ActionEvent e) {
      sb.append(5);
      text1.setText(sb.toString());
     }
   
    });
    buttons[6].setBounds(130, 100, 50, 40);
    buttons[6].addActionListener(new ActionListener() {
   
     public void actionPerformed(ActionEvent e) {
      sb.append(6);
      text1.setText(sb.toString());
     }
   
    });
    buttons[7].setBounds(190, 100, 50, 40);
    buttons[7].addActionListener(new ActionListener() {
   
     public void actionPerformed(ActionEvent e) {
      sb.append(7);
      text1.setText(sb.toString());
     }
   
    });
    buttons[8].setBounds(10, 150, 50, 40);
    buttons[8].addActionListener(new ActionListener() {
   
     public void actionPerformed(ActionEvent e) {
      sb.append(8);
      text1.setText(sb.toString());
     }
   
    });
    buttons[9].setBounds(70, 150, 50, 40);
    buttons[9].addActionListener(new ActionListener() {
   
     public void actionPerformed(ActionEvent e) {
      sb.append(9);
      text1.setText(sb.toString());
     }
   
    });
    buttons[10].setBounds(130, 150, 50, 40);
    buttons[10].addActionListener(new ActionListener() {
   
     public void actionPerformed(ActionEvent e) {
      sign = "+";
      no1 = text1.getText();
      sb.delete(0, sb.capacity());
   
     }
    });
    buttons[11].setBounds(190, 150, 50, 40);
    buttons[11].addActionListener(new ActionListener() {
   
     public void actionPerformed(ActionEvent e) {
      sign = "-";
      no1 = text1.getText();
      sb.delete(0, sb.capacity());
   
     }
    });
    buttons[12].setBounds(10, 200, 50, 40);
    buttons[12].addActionListener(new ActionListener() {
   
     public void actionPerformed(ActionEvent e) {
      sign = "*";
      no1 = text1.getText();
      sb.delete(0, sb.capacity());
   
     }
    });
    buttons[13].setBounds(70, 200, 50, 40);
    buttons[13].addActionListener(new ActionListener() {
   
     public void actionPerformed(ActionEvent e) {
      sign = "/";
      no1 = text1.getText();
      sb.delete(0, sb.capacity());
   
     }
    });
    buttons[14].setForeground(Color.RED);
    buttons[14].setBounds(130, 200, 50, 40);
    buttons[14].addActionListener(new ActionListener() {
   
     public void actionPerformed(ActionEvent e) {
      int sum = 0;//最终结果
      if (sign.equals("+")) {
       int no2 = Integer.parseInt(no1);//取得前一个数
   
       int no3 = Integer.parseInt(text1.getText());//取得现在的数
   
       sum = no2 + no3;//累加
   
       text1.setText(String.valueOf(sum));
   
      }
      if (sign.equals("-")) {
       int no2 = Integer.parseInt(no1);
   
       int no3 = Integer.parseInt(text1.getText());
   
       sum = no2 - no3;
   
       text1.setText(String.valueOf(sum));
   
      }
      if (sign.equals("*")) {
       int no2 = Integer.parseInt(no1);
   
       int no3 = Integer.parseInt(text1.getText());
   
       sum = no2 * no3;
   
       text1.setText(String.valueOf(sum));
   
      }
   
      if (sign.equals("/")) {
       int no2 = Integer.parseInt(no1);
   
       int no3 = Integer.parseInt(text1.getText());
   
       sum = no2 / no3;
   
       text1.setText(String.valueOf(sum));
   
      }
   
     }
   
    });
    buttons[15].setBounds(190, 200, 50, 40);
    buttons[15].addActionListener(new ActionListener() {
   
     public void actionPerformed(ActionEvent e) {
      sb.delete(0, sb.capacity());//清除sb的内容
      text1.setText("");//结果框设置为空
     }
    });
   
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);//响应关闭窗口
    setVisible(true);//显示窗口
   }
   }
   
   2.主程序类
   package Calc;
   
   public class CalcTest {
   
   public static void main(String[] args) {
    CalcFrame f = new CalcFrame();
   
   }
   
   }

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Answer 2