Array Element Assignment

Case 1: In case of primitive types as array elements we can provide any type which can be implicitly promoted to declared type.

ex:  int[] x = new int[4];

x[0] = 12;

x[1] = 'a';

byte b = 13;

x[2] = b;

short s = 34;

x[3] = s;

x[4] = 16L;  // CE: Possible loss of precision
found long required int

 In case of float array the allowed data type are byte, short, char, int long float.

Case 2: In case of Object type arrays, As array elements we can provide either declare type objects or its child class objects.

Ex: Object[] obj = new Object[10];

obj[0] = new Object();

obj[1] = new Integer(1);

obj[2] = new String("Arrays");

Ex: Number[] num = new Number[10];

num[0] = new Integer(10);

num[1] = new Double(10.2);

num[2] = new String("Arrays");  CE: Incompatible Types foud java.lang.String required java.lang.Number

Case 3: For interface type arrays as array elements , its implementation class objects are allowed.

Runnabale[] r = new Runnable[2];

r[0] =  new Thread();

r[1] = new String("Arrays");  CE: Incompatible Types foud java.lang.String required java.lang.Runnable

ARRAY VARIABLE ASSIGNMENT

Case 1: Element level promotions are not applicable at array level
for ex char element can be promoted to int type whereas char array cannot be promoted to int array.
eg: char[] ch = {'a','b','c'};
int[] x = ch;    CE: incompatible types found char[] required int[].


Questions: Which of the following promotions will be performed automatically. 
char to int  //valid
char[] to int  //invalid
int to double  // valid
int[] to double[]  //invalid
float to int  //invalid
float[] to int[]  // invalid
String to Object  // valid
String[] to Object[]  // valid

But in the case of Object type arrays  child class type array can be promoted to Parent class type array.
String[] s = {"a","aa"};
Object[] c = s;

Case 2: Whenever we are assigning one array to another array internal elements won't be copied just reference variable will be reassigned.
ex: int[] a = {1,2,3,4};
int[] b = {1,2};
a = b;  valid
b = a; valid

Case 3: Whenever we are assigning one array to another array dimensions must be matched. 
for ex: In the place of int[] we  should provide One dimensional array only, If we are trying to provide any other dimension then we will get compile time error.
int[][] x = new int[3][2];
x[0] = new int[4][3];  CE: incompatible types found int[][] required int[]
x[0] = 10; incompatible type found int required int[]
x[0] = new int[10]; valid

Wheneever we are assigning one array to another array both dimensions of the type must be matched but sizes are not required to match.


QUESTION 
class Test{
public static void main(String [] srgs){
    for(int i =0; i <= args.length;i++){
        System.out.println(args[i]);
     }
  }
}

Java Test A B C : 
A
B
C
RE: IndexOutOfBoundsException

Java Test :
RE: IndexOutOfBoundsException



class Test{
public static void main(String [] srgs){
String[] argh = {"x","Y","Z"};
args = argh;
for(String s in args){
System.out.println(s);
}
}
}

Java Test A B C : 
X
Y
Z

Java Test :
X
Y
Z



int[][] x = new int[4][3];
a[0] = new int[4];
a[1] = new int[2];
a = new int[3][2];

Ques: How many objects are created ?   --> 11


Ques: How many objects eligible for Garbage Collection ?  --> 7