Java instanceof operator __effective Java 2.0_item 8 knowledge Point __java

Article Author: Tyan
Blog: noahsnail.com |  CSDN | Jianshu

The instanceof operator is a two-dollar operator and is a reserved keyword in java. Its role is to determine whether its left object is an instance of its right class, and returns a Boolean type of data. Can be used to determine whether an object is an instance of a particular class or an instance of its subclass.

The use of instanceof is:

Boolean result = Object instanceof class

Its parameters are:

Result: Boolean type.

Object: Any expression of objects.

Class: Any defined object class.

Example:

Import java.util.ArrayList;
Import java.util.Collection;
Import java.util.List;

public class Test {public

    static void Main (string[] args) {
        String s  = ' abc ';
        System.out.println (S instanceof String);

        list<string> list = new arraylist<> ();
        SYSTEM.OUT.PRINTLN (list instanceof Collection);

        SYSTEM.OUT.PRINTLN (null instanceof String);
    }

Test results:

True
True
False

Note: The instanceof operator is primarily used to determine the type of object that is used by the Equals method of the object.