Java代码大全：终极编程指南 |21xrx.com

Java代码大全：终极编程指南

2023-06-13 21:03:11 深夜i -- --

Java 代码初学者

Java作为一门常用的编程语言，它的应用范围十分广泛，涉及到Java的技术岗位从未减少过。在Java的编程过程中，我们经常需要使用许多编写的Java代码。对于初学者，他们往往会遇到如何编写Java代码的问题。因此，本文为大家介绍一份Java代码大全，作为终极的Java编程指南，以便初学者快速上手。

1、Java基础

- Hello World 示例代码：


public class HelloWorld {
  public static void main(String[] args) {
    System.out.println("Hello, World");
  }
}

- Java数据类型示例代码：


public class DataType {
  public static void main(String[] args)
    byte b = 10;
    short s = 100;
    int i = 1000;
    long l = 10000L;
    float f= 1.2f;
    double d = 1.234d;
    boolean bool = true;
    char c = 'A';
  
}

- Java运算符示例代码：


public class Operator {
  public static void main(String[] args) {
    int a = 10;
    int b = 20;
    int c = 30;
    System.out.println(a + b);
    System.out.println(b - a);
    System.out.println(a * b);
    System.out.println(b / a);
    System.out.println(c % a);
  }
}

2、Java面向对象

- 类与对象示例代码：


public class Person {
  String name;
  int age;
  String gender;
  public void eat() {
    System.out.println("Person is eating.");
  }
  public void sleep() {
    System.out.println("Person is sleeping.");
  }
  public static void main(String[] args) {
    Person person = new Person();
    person.name = "张三";
    person.age = 18;
    person.gender = "男";
    person.eat();
    person.sleep();
  }
}

- 继承与多态示例代码：


public class Animal {
  public void eat() {
    System.out.println("Animal is eating.");
  }
}
public class Dog extends Animal {
  public void eat() {
    System.out.println("Dog is eating.");
  }
}
public class Cat extends Animal {
  public void eat() {
    System.out.println("Cat is eating.");
  }
}
public class Test {
  public static void main(String[] args) {
    Animal animal1 = new Dog();
    Animal animal2 = new Cat();
    animal1.eat();
    animal2.eat();
  }
}

- 抽象类与接口示例代码：


public abstract class Animal {
  public abstract void eat();
  public abstract void sleep();
}
public interface Flyable{
  void fly();
}
public class Dog extends Animal {
  public void eat() {
    System.out.println("Dog is eating.");
  }
  public void sleep() {
    System.out.println("Dog is sleeping.");
  }
}
public class Bird extends Animal implements Flyable {
  public void eat() {
    System.out.println("Bird is eating.");
  }
  public void sleep() {
    System.out.println("Bird is sleeping.");
  }
  public void fly() {
    System.out.println("Bird is flying.");
  }
}

3、Java高级

- 多线程示例代码：


public class MyThread extends Thread{
  public void run(){
    System.out.println("Thread is running.");
  }
  public static void main(String[] args) {
    MyThread myThread = new MyThread();
    myThread.start(); // 调用start方法，执行run方法
  }
}

- 异常处理示例代码：


public class ExceptionTest {
  public static void main(String[] args) {
    try
      int a = 0;
      int b = 1 / a;
     catch (ArithmeticException e) {
      System.out.println("除数不能为0！");
    }
  }
}

- IO与文件操作示例代码：


public class FileTest {
  public static void main(String[] args) {
    File file = new File("test.txt");
    try {
      BufferedWriter bw = new BufferedWriter(new FileWriter(file));
      bw.write("hello,world");
      bw.flush();
      bw.close();
      BufferedReader br = new BufferedReader(new FileReader(file));
      String str = "";
      while ((str = br.readLine()) != null) {
        System.out.println(str);
      }
      br.close();
    } catch (IOException e) {
      e.printStackTrace();
    }
  }
}

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