What are static objects and methods in java

What is a static variable

Members modified by static in Java are called static members or class members. It belongs to the entire class, not to an object, that is, it is shared by all objects of the class. Static members can be accessed directly using the class name, or they can be accessed using the object name.

Use static to modify variables, methods and code blocks.

public class Test1 {
    // static修饰的变量为静态变量，所有类的对象共享hobby
    static String hobby = "Tedu";
    
    public static void main(String[] args) {
        // 静态变量可以直接使用类名来访问，无需创建对象
        System.out.println("通过类名访问hobby：" + Test1.hobby);
        // 创建类的对象
        Test1 t1 = new Test1();
        // 使用对象名访问静态变量
        System.out.println("使用对象名访hobby:" + t1.hobby);
        // 使用对象名的形式修改静态变量的值
        t1.hobby = "cjj";
        // 再次使用类名访问静态白变量，值已经被修改
        System.out.println("通过类名访问hobby：" + Test1.hobby);
    }
}

Running result:

通过类名访问hobby：Tedu
使用对象名访hobby:Tedu
通过类名访问hobby：cjj

Note: Static members belong to the entire class. When the system uses the class for the first time, it will allocate memory space until the Resources will be recycled only after the class is unloaded!

What is a static method

Like static variables, we can also use static modified methods, called static methods or class methods. In fact, the main method we have been writing before is a static method.

public class Test01 {
    //使用static关键字声明静态方法
    public static void print() {
        System.out.println("欢迎你：Cjj!");
    }
    public static void main(String[] args) {
        //直接使用类名调用静态方法
        Test01.print();
        //也可以通过对象名调用，当然更推荐使用类名调用
        Test01 t1 = new Test01();
        t1.print();
    }
}

Running result:

欢迎你：Cjj!
欢迎你：Cjj!

Note:

1. Static methods can directly call static members of the same class, but cannot directly call non-static members. static members. For example:

If you want to call non-static variables in a static method, you can create an object of the class and then access the non-static variables through the object. For example:

2. In ordinary member methods, you can directly access non-static variables and static variables of the same type, such as:

3. Non-static methods cannot be directly called in static methods. Non-static methods need to be accessed through objects. Such as:

public class Test01 {
    String name = "Cjj"; //静态成员变量
    static String hobby = "study"; //非静态成员变量
    
    //普通成员方法
    public void print1() {
        System.out.println("普通成员方法~~~"); 
    }
    
    //静态成员方法
    public static void print2() {
        System.out.println("静态成员方法~~~");
    }
    
    public static void main(String[] args) {
        //普通成员方法必须通过对象来调用
        Test01 t1 = new Test01();
        t1.print1();
        //可以直接调用静态方法
        print2();
    }
}

Recommended tutorial: java introductory tutorial

The above is the detailed content of What are static objects and methods in java. For more information, please follow other related articles on the PHP Chinese website!