Java static关键字

未使用static

class Test {
    private int age;

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public Test(int age) {
        super();
        this.age = age;
    }

};

public class Static {

    public static void main(String[] args) {
        // TODO Auto-generated method stub

        Test t1 = new Test(10);
        System.out.println(t1.getAge());

        Test t2 = new Test(11);
        System.out.println(t2.getAge());
    }

}

//运行结果
10
11

使用static

class Test {
    static int age; //全局有效

    public int getAge() {
        return age;
    }

    public static void setAge(int age) { //必须声明static
        Test.age = age; //用类名的方式
    }

    public Test(int age) {
        super();
        Test.age = age;
    }

};

public class Static {

    public static void main(String[] args) {
        // TODO Auto-generated method stub

        Test t1 = new Test(10);
        Test t2 = new Test(11);

        Test.age = 5; //用类名调用

        System.out.println(t1.getAge());
        System.out.println(t2.getAge());
    }

}

//运行结果
5
5