Java 开发实用文档#

本实用文档总结了 Java 开发中的常见功能实现与代码模板，适用于桌面应用、控制台程序或基础服务端逻辑开发。适合初学者与日常开发参考使用。

1. 输入输出（IO）#

1.1 控制台输入#

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import java.util.Scanner;
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public class InputExample {
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    public static void main(String[] args) {
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        Scanner scanner = new Scanner(System.in);
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        System.out.print("请输入你的名字: ");
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        String name = scanner.nextLine();
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        System.out.println("你好, " + name);
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        scanner.close();
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    }
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}

1.2 文件读写#

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import java.io.*;
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public class FileExample {
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    public static void main(String[] args) throws IOException {
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        // 写入文件
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        FileWriter writer = new FileWriter("example.txt");
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        writer.write("Hello, Java!");
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        writer.close();
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        // 读取文件
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        BufferedReader reader = new BufferedReader(new FileReader("example.txt"));
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        String line;
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        while ((line = reader.readLine()) != null) {
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            System.out.println(line);
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        }
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        reader.close();
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    }
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}

2. 常用数据结构#

2.1 ArrayList 使用#

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import java.util.ArrayList;
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public class ListExample {
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    public static void main(String[] args) {
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        ArrayList<String> list = new ArrayList<>();
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        list.add("Apple");
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        list.add("Banana");
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        list.remove("Apple");
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        for (String item : list) {
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            System.out.println(item);
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        }
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    }
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}

2.2 HashMap 使用#

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import java.util.HashMap;
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public class MapExample {
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    public static void main(String[] args) {
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        HashMap<String, Integer> map = new HashMap<>();
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        map.put("A", 1);
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        map.put("B", 2);
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        System.out.println(map.get("A"));
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    }
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}

3. 面向对象基础#

3.1 定义类与方法#

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public class Person {
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    private String name;
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    public Person(String name) {
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        this.name = name;
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    }
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    public void sayHello() {
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        System.out.println("Hello, my name is " + name);
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    }
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}

3.2 使用类#

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public class Main {
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    public static void main(String[] args) {
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        Person p = new Person("Tom");
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        p.sayHello();
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    }
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}

4. 异常处理#

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public class ExceptionExample {
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    public static void main(String[] args) {
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        try {
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            int a = 10 / 0;
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        } catch (ArithmeticException e) {
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            System.out.println("除数不能为0");
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        } finally {
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            System.out.println("无论如何都会执行");
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        }
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    }
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}

5. 多线程#

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public class MyThread extends Thread {
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    public void run() {
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        System.out.println("线程运行中...");
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    }
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    public static void main(String[] args) {
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        MyThread t = new MyThread();
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        t.start();
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    }
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}

或者使用 Runnable 接口：

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public class MyRunnable implements Runnable {
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    public void run() {
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        System.out.println("Runnable 线程运行中...");
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    }
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    public static void main(String[] args) {
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        Thread t = new Thread(new MyRunnable());
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        t.start();
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    }
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}

6. 网络编程（Socket）#

6.1 服务器端#

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import java.net.*;
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import java.io.*;
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public class Server {
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    public static void main(String[] args) throws IOException {
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        ServerSocket server = new ServerSocket(8888);
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        Socket socket = server.accept();
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        BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
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        String message = in.readLine();
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        System.out.println("收到客户端消息: " + message);
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        socket.close();
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        server.close();
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    }
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}

6.2 客户端#

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import java.net.*;
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import java.io.*;
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public class Client {
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    public static void main(String[] args) throws IOException {
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        Socket socket = new Socket("localhost", 8888);
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        PrintWriter out = new PrintWriter(socket.getOutputStream(), true);
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        out.println("Hello Server");
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        socket.close();
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    }
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}