Difference between array definition and declaration?

Answer 1

Have a look at this example with an abstract class... Declaration means you just tell the compiler that there is a class, variable or method, but not what it is doing. Just like a template.
To actually 'use' a class, method, variable you have to tell the compiler what it is supposed to do by defining them. Example:

// ** declaration
// class
abstract class myClass {
// variable
int i;
// method
abstract void doSomething(){};
};

// ** definition
// class
public class myDerivedClass extends myClass{
// variable
int x =1;
// method
@Override
void doSomething (){
System.out.print ('method body defines
what this method is supposed to do');
};
};

Answer 2

For an array:
int[] myArray; // declaration
myArray = new int[]{1, 2, 3}; // definition

Answer 3

array definition ..it is all about creating a reference variable..but when you declare it ..you are asigning(alocating) a memory location and size of your array.