Java应用程序开发实例 |21xrx.com

Java应用程序开发实例

2023-06-15 00:16:14 深夜i -- --

Java 应用程序 Swing框架

Java作为一门广泛应用于企业级应用开发的语言，其强大的跨平台特性以及兼具面向对象特性的编程语言，使其成为了软件开发领域的一种重要语言。在本篇文章中，将会通过一个Java应用程序的开发实例，展示Java在应用开发领域的应用。

本实例将基于Java Swing框架开发一个简单的窗口应用程序，实现一个计算器，用户可以通过该应用程序进行简单的四则运算。以下是Java应用程序的开发步骤：

第一步：创建Java项目和类文件

在Eclipse或IntelliJ IDEA等Java开发工具中，创建一个Java项目，并在该项目中创建一个Calculator类。

第二步：编写Java程序

在Calculator类中，使用Swing框架中的JFrame类创建一个应用程序窗口，并在该窗口中添加一些按钮和文本框等控件，实现一个简单的计算器。

代码案例：


import java.awt.EventQueue;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import javax.swing.JTextField;
import javax.swing.JButton;
import java.awt.Font;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
public class Calculator extends JFrame {
private JPanel contentPane;
private JTextField textField;
private JButton btn1;
private JButton btn2;
private JButton btn3;
private JButton btn4;
private JButton btn5;
private JButton btn6;
private JButton btn7;
private JButton btn8;
private JButton btn9;
private JButton btn0;
private JButton btnPlus;
private JButton btnMinus;
private JButton btnMultiple;
private JButton btnDivide;
private JButton btnClear;
private JButton btnEquals;
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
Calculator frame = new Calculator();
frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
public Calculator() {
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setBounds(100, 100, 300, 300);
contentPane = new JPanel();
contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
setContentPane(contentPane);
contentPane.setLayout(null);
textField = new JTextField();
textField.setBounds(10, 11, 264, 36);
contentPane.add(textField);
textField.setColumns(10);
btn1 = new JButton("1");
btn1.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
textField.setText(textField.getText() + "1");
}
});
btn1.setFont(new Font("Tahoma", Font.BOLD, 18));
btn1.setBounds(10, 58, 60, 36);
contentPane.add(btn1);
btn2 = new JButton("2");
btn2.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
textField.setText(textField.getText() + "2");
}
});
btn2.setFont(new Font("Tahoma", Font.BOLD, 18));
btn2.setBounds(80, 58, 60, 36);
contentPane.add(btn2);
btn3 = new JButton("3");
btn3.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
textField.setText(textField.getText() + "3");
}
});
btn3.setFont(new Font("Tahoma", Font.BOLD, 18));
btn3.setBounds(150, 58, 60, 36);
contentPane.add(btn3);
btnPlus = new JButton("+");
btnPlus.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
textField.setText(textField.getText() + "+");
}
});
btnPlus.setFont(new Font("Tahoma", Font.BOLD, 18));
btnPlus.setBounds(220, 58, 60, 36);
contentPane.add(btnPlus);
btn4 = new JButton("4");
btn4.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
textField.setText(textField.getText() + "4");
}
});
btn4.setFont(new Font("Tahoma", Font.BOLD, 18));
btn4.setBounds(10, 105, 60, 36);
contentPane.add(btn4);
btn5 = new JButton("5");
btn5.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
textField.setText(textField.getText() + "5");
}
});
btn5.setFont(new Font("Tahoma", Font.BOLD, 18));
btn5.setBounds(80, 105, 60, 36);
contentPane.add(btn5);
btn6 = new JButton("6");
btn6.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
textField.setText(textField.getText() + "6");
}
});
btn6.setFont(new Font("Tahoma", Font.BOLD, 18));
btn6.setBounds(150, 105, 60, 36);
contentPane.add(btn6);
btnMinus = new JButton("-");
btnMinus.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
textField.setText(textField.getText() + "-");
}
});
btnMinus.setFont(new Font("Tahoma", Font.BOLD, 18));
btnMinus.setBounds(220, 105, 60, 36);
contentPane.add(btnMinus);
btn7 = new JButton("7");
btn7.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
textField.setText(textField.getText() + "7");
}
});
btn7.setFont(new Font("Tahoma", Font.BOLD, 18));
btn7.setBounds(10, 152, 60, 36);
contentPane.add(btn7);
btn8 = new JButton("8");
btn8.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
textField.setText(textField.getText() + "8");
}
});
btn8.setFont(new Font("Tahoma", Font.BOLD, 18));
btn8.setBounds(80, 152, 60, 36);
contentPane.add(btn8);
btn9 = new JButton("9");
btn9.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
textField.setText(textField.getText() + "9");
}
});
btn9.setFont(new Font("Tahoma", Font.BOLD, 18));
btn9.setBounds(150, 152, 60, 36);
contentPane.add(btn9);
btnMultiple = new JButton("*");
btnMultiple.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
textField.setText(textField.getText() + "*");
}
});
btnMultiple.setFont(new Font("Tahoma", Font.BOLD, 18));
btnMultiple.setBounds(220, 152, 60, 36);
contentPane.add(btnMultiple);
btn0 = new JButton("0");
btn0.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
textField.setText(textField.getText() + "0");
}
});
btn0.setFont(new Font("Tahoma", Font.BOLD, 18));
btn0.setBounds(80, 199, 60, 36);
contentPane.add(btn0);
btnClear = new JButton("C");
btnClear.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
textField.setText("");
}
});
btnClear.setFont(new Font("Tahoma", Font.BOLD, 18));
btnClear.setBounds(10, 199, 60, 36);
contentPane.add(btnClear);
btnEquals = new JButton("=");
btnEquals.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
String expression = textField.getText();
if (expression.matches("^-?\\d+([+\\-*/]\\d+)+$")) {
  String temp = expression.replaceAll("-", "&");
  String[] nums = temp.split("[+|&|*|/]");
  String[] symbols = expression.split("\\d+");
  double[] newNums = new double[nums.length];
  for (int i = 0; i < nums.length; i++) {
    if (nums[i].contains("&")) {
      newNums[i] = Double.parseDouble(nums[i].replace("&", "-"));
    } else {
      newNums[i] = Double.parseDouble(nums[i]);
    }
  }
  double result = newNums[0];
  for (int i = 1; i < symbols.length; i++) {
    if (symbols[i].equals("+")) {
      result += newNums[i];
    } else if (symbols[i].equals("-")) {
      result -= newNums[i];
    } else if (symbols[i].equals("*")) {
      result *= newNums[i];
    } else if (symbols[i].equals("/")) {
      if (newNums[i] != 0) {
        result /= newNums[i];
      } else {
        textField.setText("除数不能为0！");
      }
    }
  }
  textField.setText(String.valueOf(result));
} else {
  textField.setText("输入格式错误！");
}
}
});
btnEquals.setFont(new Font("Tahoma", Font.BOLD, 18));
btnEquals.setBounds(150, 199, 130, 36);
contentPane.add(btnEquals);
btnDivide = new JButton("/");
btnDivide.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
textField.setText(textField.getText() + "/");
}
});
btnDivide.setFont(new Font("Tahoma", Font.BOLD, 18));
btnDivide.setBounds(220, 199, 60, 36);
contentPane.add(btnDivide);
}
}

第三步：运行Java应用程序

在开发工具中，单击“运行”按钮或使用快捷键“Ctrl + F11”运行Java应用程序。

通过以上实例，可以看出Java在应用程序开发方面的应用非常广泛，尤其是在企业级应用领域。无论是桌面应用程序、Web应用程序还是移动应用程序，都可以使用Java语言进行开发。同时也要注意Java应用程序的安全性和稳定性，因为大量的企业级应用程序正在使用Java语言进行开发。

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