What is .intValue() in Java?

Question

What is the difference between them?

l is an arraylist of Integer type.

version 1:

int[] a = new int[l.size()];
for (in         


        

Answer 1

It's just a convenience method for getting primitive value from object of Number: http://docs.oracle.com/javase/1.4.2/docs/api/java/lang/Number.html

Consider the code:

Integer integerValue = Integer.valueOf(123);
float floatValue = integerValue.floatValue();

The last line is a convenient method to do:

float floatValue = (float)(int)integerValue;

Since any numeric type in Java can be explicitly cast to any other primitive numeric type, Number class implements all these conversions. As usual, some of them don't make much sense:

Integer integerValue = Integer.valueOf(123);
int intValue = integerValue.intValue();
int intValue2 = (int)integerValue;
int intValue3 = integerValue;