【软件设计师备考 专题 】C、C++、Java、Visual Basic、Visual C++等语言的基础知识和应用（二）

// 定义一个类
class Person {
    String name;
    int age;
    void displayInfo() {
        System.out.println("姓名：" + name);
        System.out.println("年龄：" + age);
    }
}
// 创建对象并使用类中的方法
public class Main {
    public static void main(String[] args) {
        Person person = new Person();
        person.name = "张三";
        person.age = 20;
        person.displayInfo();
    }
}

// 定义一个接口
interface Shape {
    double getArea();
    double getPerimeter();
}
// 实现接口的类
class Circle implements Shape {
    double radius;
    @Override
    public double getArea() {
        return Math.PI * radius * radius;
    }
    @Override
    public double getPerimeter() {
        return 2 * Math.PI * radius;
    }
}
// 继承抽象类的子类
abstract class Animal {
    abstract void sound();
}
class Dog extends Animal {
    @Override
    void sound() {
        System.out.println("汪汪汪");
    }
}
// 使用接口和抽象类
public class Main {
    public static void main(String[] args) {
        Circle circle = new Circle();
        circle.radius = 5;
        System.out.println("面积：" + circle.getArea());
        System.out.println("周长：" + circle.getPerimeter());
        Dog dog = new Dog();
        dog.sound();
    }
}

public class Main {
    public static void main(String[] args) {
        try {
            int[] arr = new int[5];
            System.out.println(arr[10]);
        } catch (ArrayIndexOutOfBoundsException e) {
            System.out.println("数组越界异常：" + e.getMessage());
        }
    }
}

class MyThread extends Thread {
    @Override
    public void run() {
        for (int i = 0; i < 5; i++) {
            System.out.println("线程执行：" + i);
        }
    }
}
public class Main {
    public static void main(String[] args) {
        MyThread thread = new MyThread();
        thread.start();
        for (int i = 0; i < 5; i++) {
            System.out.println("主线程执行：" + i);
        }
    }
}

import java.io.*;
import java.net.*;
public class Server {
    public static void main(String[] args) {
        try {
            ServerSocket serverSocket = new ServerSocket(8888);
            System.out.println("服务器启动，等待客户端连接...");
            Socket socket = serverSocket.accept();
            System.out.println("客户端连接成功！");
            BufferedReader reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            String message = reader.readLine();
            System.out.println("收到客户端消息：" + message);
            BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));
            writer.write("Hello, Client!");
            writer.newLine();
            writer.flush();
            System.out.println("回复消息给客户端成功！");
            reader.close();
            writer.close();
            socket.close();
            serverSocket.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

import android.app.Activity;
import android.os.Bundle;
import android.widget.TextView;
public class MainActivity extends Activity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        TextView textView = findViewById(R.id.text_view);
        textView.setText("Hello, Android!");
    }
}