Java的instanceof用法

instanceof的作用是判斷左面的對象是否是右面類的實例
1.instanceof是一個雙目運算符，該運算符與“==”，“>”等類似，該運算符左面是一個實例化的對象，右面是類。
2.當左面的對象是右面類創建的對象時，既是左面的對象是右面類的實例，返回true，否則返回false。
示例：

Animal類：

public class Animal {
public String weight;
public String height;
public String getWeight() {
    return weight;
}
public void setWeight(String weight) {
    this.weight = weight;
}
public String getHeight() {
    return height;
}
public void setHeight(String height) {
    this.height = height;
}
}

Cat類：

public class Cat extends Animal {
public String  paw;
public String getPaw() {
    return paw;
}
public void setPaw(String paw) {
    this.paw = paw;
	 }
}

Rabbit類：

public class Rabbit extends Animal{
}

Rose類：

public class Rose extends Rabbit {
}

Main：

public class Main {
public static void main(String[] args){
    Cat cat = new Cat();
    Rose rose = new Rose();
    Boolean in = cat instanceof  Cat;
    System.out.println("cat是Cat的實例: "+in);

    Boolean in1 = cat instanceof Animal;
    System.out.println("cat是Animal的實例: "+in1);

    Boolean in2 = rose instanceof Animal;
    System.out.println("rose是Animal的實例: "+in2);

    Rose rose1 = null;
    Boolean in3 = rose1 instanceof  Rose;
    System.out.println("rose（null）是Rose的實例 :"+in3);
}
}

返回結果：

cat是Cat的實例true
cat是Animal的實例true
rose是Animal的實例true
rose（null）是Rose的實例false