2.txt

简单的进行加,减,乘,除计算.代码简单,并且非常适合于Java的初学者.

package DeBo.Test7;

/*
 *设计一个简单计算器，
 在“操作数”标签右侧的两个文本框输入操作数，
 当单击操作符＋，－，×，÷按钮时，
 对两个操作数进行运算并将结果填入到“结果”标签右侧的文本框中
 */
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class JSQ extends JFrame implements ActionListener {
 JLabel l1, l2, l3;

 JTextField t1, t2, t3;

 JButton b1, b2, b3, b4;

 public JSQ() {
  super("简单计算器");
  l1 = new JLabel("操作数");
  l2 = new JLabel("操作数");
  l3 = new JLabel("结果");
  t1 = new JTextField(10);
  t2 = new JTextField(10);
  t3 = new JTextField(10);
  // 将窗口物体放入窗口
  GridBagLayout layout = new GridBagLayout();
  getContentPane().setLayout(layout);
  addComponent(layout, l1, 1, 0, 1, 1);
  addComponent(layout, l2, 2, 0, 1, 1);
  addComponent(layout, l3, 3, 0, 1, 1);
  addComponent(layout, t1, 1, 1, 1, 1);
  addComponent(layout, t2, 2, 1, 1, 1);
  addComponent(layout, t3, 3, 1, 1, 1);

  b1 = new JButton("+");
  b2 = new JButton("-");
  b3 = new JButton("*");
  b4 = new JButton("/");
  addComponent(layout, b1, 1, 2, 1, 1);
  addComponent(layout, b2, 1, 3, 1, 1);
  addComponent(layout, b3, 3, 2, 1, 1);
  addComponent(layout, b4, 3, 3, 1, 1);
  b1.addActionListener(this);
  b2.addActionListener(this);
  b3.addActionListener(this);
  b4.addActionListener(this);
  this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
 }

 public void actionPerformed(ActionEvent j) {
  double n;
  try {
   if (j.getSource() == b1) {
    double n1, n2;
    n1 = Double.parseDouble(t1.getText());
    n2 = Double.parseDouble(t2.getText());
    n = n1 + n2;
    t3.setText(String.valueOf(n));
   }
   if (j.getSource() == b2) {
    double n1, n2;
    n1 = Double.parseDouble(t1.getText());
    n2 = Double.parseDouble(t2.getText());
    n = n1 - n2;
    t3.setText(String.valueOf(n));
   }
   if (j.getSource() == b3) {
    double n1, n2;
    n1 = Double.parseDouble(t1.getText());
    n2 = Double.parseDouble(t2.getText());
    n = n1 * n2;
    t3.setText(String.valueOf(n));
   }
   if (j.getSource() == b4) {
    double n1, n2;
    n1 = Double.parseDouble(t1.getText());
    n2 = Double.parseDouble(t2.getText());
    n = n1 / n2;
    t3.setText(String.valueOf(n));
   }
  } catch (Exception e) {
  }
 }

 // 快捷使用GridBagLayout的方法
 private void addComponent(GridBagLayout layout, Component component,
   int row, int col, int width, int height) {
  GridBagConstraints constraints = new GridBagConstraints();
  constraints.fill = GridBagConstraints.BOTH;
  constraints.insets = new Insets(10, 2, 10, 2);
  constraints.weightx = 200;
  constraints.weighty = 200;
  constraints.gridx = col;
  constraints.gridy = row;
  constraints.gridwidth = width;
  constraints.gridheight = height;
  layout.setConstraints(component, constraints);
  if (component instanceof JButton)
   ((JButton) component).addActionListener(this);
  getContentPane().add(component);
 }

 // 主方法初始化并显示窗口
 public static void main(String[] args) {
  JSQ calc = new JSQ();
  calc.pack();
  calc.setVisible(true);
 }
}