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In Java, all parameters are passed by value, but for arrays and objects of classes only a reference to the actual parameter, which really is a pointer, is passed. Therefore changing an array element or a class field inside the function does change the actual parameter's element or field. Being a programmer, this demands extra care from you. This would become clearer as you go through the following code examples of parameter passing by value and parameter passing by reference in Java:

PARAMETER PASSING BY REFERENCE:

void f( int [ ] A ) { 
   A[0] = 10; 	// change an element of parameter A 
} 

void g() { 
   int [ ] B = new int [3]; 
   B[0] = 5; 
   f(B); 
			// B[0] is now 10, because function f changed the
			// first element of the array 
}

PARAMETER PASSING BY VALUE:

void f( int A ) { 
   A = 10; 	// change the value of parameter A to 10
} 

void g() { 
   int B =  5; 
   f(B); 
			// B has not changed even though the function f changed the
			// value to 10 
}

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