类变量/静态变量

该变量最大的特点就是能被一个类的所有对象实例共享

该变量在类加载的时候就生成了

方法中不涉及到任何跟对象相关的成员，可以把方法设置成静态方法 

【不创建对象也能使用方法（把方法当作工具用）】

类方法无this，无super

类方法只能访问静态变量或者静态方法（普通成员方法二者都可以访问）

package Static_;

//类变量
public class Static01 {
    public static void main(String[] args) {
        child c1 = new child();
        child c2 = new child();
        child c3 = new child();
        //访问方法（遵循访问规则）
        //类变量随着类的创建而创建，所以不创建类的对象也可以访问类变量
        System.out.println(child.getWeight());//类名.类变量名
        System.out.println(c1.weight);//用对象去访问
    }
}
class child{
    private int age;
    //类变量的两种定义方法
    public static int weight = 9;
    static private int height = 7;
    public int getAge() {
        return age;
    }

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

    public static int getWeight() {
        return weight;
    }

    public static void setWeight(int weight) {
        child.weight = weight;
    }

    public static int getHeight() {
        return height;
    }

    public static void setHeight(int height) {
        child.height = height;
    }

    public void print(){
        System.out.println(this.age);
    }
}

package Static_;

//类变量
public class Static01 {
    public static void main(String[] args) {
        child c1 = new child();
        child c2 = new child();
        child c3 = new child();
        //访问方法（遵循访问规则）
        //类变量随着类的创建而创建，所以不创建类的对象也可以访问类变量
        System.out.println(child.getWeight());//类名.类变量名
        System.out.println(c1.weight);//用对象去访问
    }
}
class child{
    private int age;
    //类变量的两种定义方法
    public static int weight = 9;
    static private int height = 7;
    public int getAge() {
        return age;
    }

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

    public static int getWeight() {
        return weight;
    }

    public static void setWeight(int weight) {
        child.weight = weight;
    }

    public static int getHeight() {
        return height;
    }

    public static void setHeight(int height) {
        child.height = height;
    }

    public void print(){
        System.out.println(this.age);
    }
}