Convert int[] to Integer[]

Convert int[] to Integer[]:

int[] primitiveArray = {1, 2, 3, 4, 5};
Integer[] objectArray = new Integer[primitiveArray.length];

for(int ctr = 0; ctr < primitiveArray.length; ctr++) {
objectArray[ctr] = Integer.valueOf(primitiveArray[ctr]); // returns Integer value
}


Convert Integer[] to int[]:

Integer[] objectArray = {1, 2, 3, 4, 5};
int[] primitiveArray = new int[objectArray.length];

for(int ctr = 0; ctr < objectArray.length; ctr++) {
primitiveArray[ctr] = objectArray[ctr].intValue(); // returns int value
}


В Java 8 мы можем сделать это

int[] ints = {1,2,3};
List list = Arrays.stream(ints).boxed().collect(Collectors.toList());

Integer обертка для int

Java caches the integer objects in the range -128 to 127

Integer i = 126;
Integer i2 = 126;

Integer i3 = 128;
Integer i4 = 128;

System.out.println(i == i2); // true, reference pointing to same literal
System.out.println(i3 == i4); // false, reference pointing to different objects

Integer i = new Integer(126);
Integer i2 = new Integer(126);

System.out.println(i == i2); // false