Different between parseInt() and valueOf() in java?

Question

How is parseInt() different from valueOf() ?

They appear to do exactly the same thing to me (also goes for parseFloat(), parseDouble(), parseLong() etc, how are they different from Long.valueOf(string) ?

Also, which one of these is preferable and used more often by convention?

Answer 1

Well, the API for Integer.valueOf(String) does indeed say that the String is interpreted exactly as if it were given to Integer.parseInt(String). However, valueOf(String) returns a new Integer() object whereas parseInt(String) returns a primitive int.

If you want to enjoy the potential caching benefits of Integer.valueOf(int), you could also use this eyesore:

Integer k = Integer.valueOf(Integer.parseInt("123")) 

Now, if what you want is the object and not the primitive, then using valueOf(String) may be more attractive than making a new object out of parseInt(String) because the former is consistently present across Integer, Long, Double, etc.

Answer 2

From this forum:

parseInt() returns primitive integer type (int), whereby valueOf returns java.lang.Integer, which is the object representative of the integer. There are circumstances where you might want an Integer object, instead of primitive type.

Of course, another obvious difference is that intValue is an instance method whereby parseInt is a static method.