The instance of keyword
The keyword instanceOf in java
programming language is a boolean operator that is used to test whether an object is
of an specified type or not and returns the value accordingly. Keywords
are basically reserved words which have specific meaning relevant to a compiler.
It takes an
object reference as its first reference and a class or interface as its second
operand and produces a result true or false based on the condition. It also lets the
developer to create their own type classes having runtime behavior specified by
the developer. aMoneyType, aDateType, aCheckingAccountID, etc are some to the
examples of the such type of classes.
Syntax: Here is the syntax for
using an instanceOf keyword
|
if (node instanceof TreeNode){
/ write your code here
}
|
Where, condition (node instanceOf TreeNode)
returns true if the class node is an instance or is an instance of a subclass of
TreeNode.
Example: Here is the example how the instanceOf
operator is used.
public class MainClass {
public static void main(String[] a) {
String s = "Hello";
if (s instanceof java.lang.String) {
System.out.println("is a String");
}
}
}
|
It returns the output "is a String" after
checking the condition because the condition returns true.
Note: Here are some points which must be noted.
- While applying the instanceOf operator on a null
reference then it returns false.
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