java - Are default field values assigned by the compiler or the JVM?

Question

I have one question: in java we declare int,long,double etc.,(primitive data) or non primitive (object data), not initialized with default values, but at run time it will take default values. Now my question is which one assigns default values: java compiler or Java Virtual Machine (JVM)?

For Example:

int x;
System.out.println(x) //Result is 0;

Answer 1

There are three different types of declared variables in Java. They are instance, class and local variables.

Instance Variables

Instance variables are the non-static fields of your class, often referred to simply as fields.

• Primitive numeric fields initialize to 0. This includes byte, short, int, long, float and double.

• booleans initialize to false .

• chars initialize to the null character u0000.

• Reference types initialize to null.

Class Variables

A class variable is a field within a class declared as static, often referred to as a static variable or static field. It is also same initialize as instance variable.

Local Variables

A local variable is a variable defined within a method, which includes any method parameters. Local variables must be initialized before use. They do not have a default value.

Initialization process is done by JVM when method is create.