How to change array elements?

Changing size of array?

• I'm doing a project for my java class and I need to change the size of an array. I know you can't actually change the size but I've heard you can do it some other way. Basically I'm writing a class for a list of int's and one of the methods I'm working on returns an array of the first few elements in the original array. The parameter is the number of elements to return. I've figured that out but the second part has me stuck. The method also has to take the original array and shorten it so that the elements returned are removed. I know you can make a shorter new array and transfer the data from the original to the new. But I need to make it so that after this method is called, any reference to the original array would be referring to the shorter one. Anyone know how i can do this?

• Answer:

  Addressing your last sentence. You can easily have the identifier point to a different array. Here's the skeleton of what you want: public int[] shortArr( int[] longArr ) { ...int shorter = // some length to be determined ...int[] retArr = new int[shorter]; // logic to fill the retArr ...return retArr; } Then in your invoking method int[] longArr = { 1,7,8,24,44 100, 72,...}; // whatever that array is longArr = shortArr( longArr ); and now longArr points to the array returned by your method. +add A comment about Ratchetr's post. You have a choice. If you want the original name to point to the new, shorter array then do what I wrote in that last statement. If you want to keep the old array then use int[] shorterArr = shortArr( longArr ); Your choice. ++add I interpret: "But I need to make it so that after this method is called, any reference to the original array would be referring to the shorter one." to mean that the identifier would now point to the newer, shorter array. That is what would happen with my last statement, repeated here: longArr = shortArr( longArr ); In a way, this is similar to what the String method substring CAN do: String str = new String( "a big ole string" ); str = str.substring( 0, 5 ); now str is "a big" The original string is gone, the identifier points to a different string. You can also say: str = "a different animal"; and now the same identifer points to still another string. Object identifiers can be reassigned, ie, point to a different object. In retrospect I see that I shouldn't have given that method a name so similar to the arrays that's it's involved with!! +++add Now I see what you're getting at with 'ANY'. I don't think that is what's meant. I think that what is meant is that of the same identifer pointing to a shorter array. +iv add Wow, there's a method in the Arrays class to do exactly what you want: int[] shortArr = Arrays.copyOf( original, newLength ); This will produce an array that only have the first newLength elements of the original array. http://docs.oracle.com/javase/6/docs/api/java/util/Arrays.html#copyOf(int%5B%5D, int)