Generic Array Tools (lend me a critical eye)

[KAJLogic]

Is there a problem with this conceptually - as in do you foresee any issues?

/*
*  Trying to make a universal tool for increment an array by one while keeping all the previous values in place.
* 
*/
                public K[] increment(K[] k){
		int i = 0;
		K[] tmp = (K[])new Object[Array.getLength(k)+1]; 
/*
* Parses through the passed k and fills tmp with all of ks values
*                
*/
		for(K kk: k){
			tmp[i] = kk;
			++i;
					}
					return tmp;
				    }

Consequently then this.

/*
*  Same with the first one, but for 2D arrays.
*
*/
	public K[][] increment(K[][] k){
		int i = 0;
		int ii = 0;
		K[][] tmp = (K[][])new Object[Array.getLength(k)+1][];
		for(K[] kara: k){
 
//          instantiate a new array at i with the length of the current iteration ( kara )
 
			tmp[i] = (K[])new Object[Array.getLength(kara)];
			for(K kay: kara){
 
   //              fill tmp's array at i with the same values of kara
 
				tmp[i][ii]=kay;
				++ii;
							}
							++i;
							ii=0;
						}	
							return tmp;	
								   }

[Norm]

What is the code supposed to do? Add some comments describing what it does and any problems it had to solve to get it to work.

[KAJLogic]

Apologies I did that. while I was looking at it I noticed I probably could have for the 2D array simply made tmp[i] = kara.

 
 
 
 
/*
*  Same with the first one, but for 2D arrays.
*
*/
	public K[][] increment(K[][] k){
		int i = 0;
		K[][] tmp = (K[][])new Object[Array.getLength(k)+1][];
		for(K[] kara: k){
 
//          just make tmp[i] = kara iteration 
// essentially use Java's built in array copy tool
			tmp[i] = kara;
							++i;
 
						}

The only thing that makes me a little uneasy about this is my lack of knowledge on how an array is copied by the API implementation.

[Norm]

The Arrays class has methods that do some of that more efficiently.

[KAJLogic]

which part?

[Norm]

The copy part

[copeg]

I'm not sure about the goal here, but if you are wishing for a more dynamic array perhaps use a List. Alternatively you can make your methods more flexible by adding a parameter which allows one to expand the array by a given value (rather than 1 every time).

Also see System (Java Platform SE 7 )

And lastly, are you looking to make a copy of the array, or reference the same (your 2D array references...and it should be noted in the comments that it does this - thus changes in the parameter array affect the returned array)

[KAJLogic]

Can you elaborate on your lastly; where does it reference?

P.S: your first suggestion is excellent I will add that.

[copeg]

Can you elaborate on your lastly; where does it reference?

Consider the following - an adaptation of your 2D array code:

public static void main(String[] args){
	int[][] a = {{1,2},{3,4}};
	int[][] b = new int[a.length+1][];
	for ( int i = 0; i < a.length; i++ ){
		b[i] = a[i];
	}
 
	System.out.println(Arrays.toString(a[0]));
	System.out.println(Arrays.toString(b[0]));
	a[0][0] = 10000;
	System.out.println(Arrays.toString(a[0]));
	System.out.println(Arrays.toString(b[0]));		
}
/*
prints:
[1, 2]
[1, 2]
[10000, 2]
[10000, 2]
 
*/

Note the above code changes a value within the a array, which also changes the value in array b because b[n] references a[n] rather than copies. Whether this is the behavior you seek I do not know, but it should be explicit in the comments. You might be better off getting explicit advice (or advice for easier alternatives) to expand upon what your goal/requirement(s) actually is

[KAJLogic]

/*
*  Same with the first one, but for 2D arrays.
*
*/
	public K[][] increment(K[][] k){
		int i = 0;
		int ii = 0;
		K[][] tmp = (K[][])new Object[Array.getLength(k)+1][];
		for(K[] kara: k){
 
//          instantiate a new array at i with the length of the current iteration ( kara )
 
			tmp[i] = (K[])new Object[Array.getLength(kara)];
			for(K kay: kara){
 
   //              fill tmp's array at i with the same values of kara
 
				tmp[i][ii]=kay;
				++ii;
							}
							++i;
							ii=0;
						}	
							return tmp;	
								   }

In my program I often find myself adding entires to arrays but of different types. I want to add this to my utility class, so I can just instantiate the type using a generic and increment my arrays with ease. I do not need to refrence each array in the parameter 2D array just copy so I can return an array exactly the same as the one in the paremeter, but the length should be greater by one.
I instantiate after the method.