All data fields in an object have default values

Question

Problem:

Are the all data type has default values in Java? I am just wondering what is the default value of an integer if I write:

int a;
boolean b;
System.out.println(a);
System.out.println(b);

All data fields in an object have default values or not? If they have default values what are they?

Thanks

Answer 1

In java, you can declare three different types of variables. They are instance, local, and class variables.

For instance variables:

# The primitive type (byte, short, int, long, float, double) variables are initialized to 0.

# Boolean initialized to false.

# char initialize to null. 

For 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 the same initialized as an instance variable.

For Local variables:

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

In a nutshell:

Data Type:              Default Value:
boolean                 false 
char                    \u0000 
int,short,byte / long   0 / 0L 
float / double          0.0f / 0.0d 
any reference type      null