They say in java "every thing is an object". Is that true?

Every object is a java.lang.Object (NOTE:java.lang.Object has no super class. ;) )

However, there are many things which are not Objects.

  • primitives and references.
  • fields (the fields themselves not the contents)
  • local variables and parameters.
  • generic classes (that may change in Java 8)
  • methods (that will change in Java 8)
  • blocks of code (that will change in Java 8)

Having a block of code as an object is one of the most exciting features in Java 8. The following examples will all be Closures and therefore objects.

x => x + 1
(x) => x + 1
(int x) => x + 1
(int x, int y) => x + y
(x, y) => x + y
(x, y) => { System.out.printf("%d + %d = %d%n", x, y, x+y); }
() => { System.out.println("I am a Runnable"); }

e.g. the block of code here will be passed as a Runnable Object

new Thread(() => { System.out.println("I am a Runnable"); }).start();

http://mail.openjdk.java.net/pipermail/lambda-dev/2011-September/003936.html


No, this is not an Object.Java is not purely Object Oriented Language because of primitives andstatic. To make primitive variable as Object java has introduced wrapper classed like Integer, Boolean etc.

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Java

Oop

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