java - How to write a generic method to insert an element in an array? -

i have input array [3, 5, 12, 8] , want output array (the input must not affeccted) identical input, element 7 inserted between 5 , 12, @ index 2 of input array.

here have far. commented out code doesn't event compile, , added couple of questions arose while trying or way:

public static <o>arraylist<o> addtoset(o[] in,o add,int newindex){ //    o obj = (o) new object(); //this doesnt work //    parameterizedtype obj = (parameterizedtype) getclass().getgenericsuperclass(); // not recognized     arraylist<o> out = multipleofsameset(obj, in.length);     if (newindex > in.length){         out = new arraylist<>(newindex+1); // noticed initializing arraylist          //like throws indexoutofboundsexception when try run out.get(),         // explain why??           out.set(newindex, add);     }     int j = 0;     int = 0;     while(j<in.length+1){         if (j==newindex){             out.set(j, add);         } else if(i<in.length){             out.set(j, in[i]);             i++;         }         j++;     }     return out; } 

the array component type string, integer or jpanel.

here generic version of code

@suppresswarnings("unchecked") public <t> t[] insertincopy(t[] src, t obj, int i) throws exception {     t[] dst = (t[]) array.newinstance(src.getclass().getcomponenttype(), src.length + 1);     system.arraycopy(src, 0, dst, 0, i);     dst[i] = obj;     system.arraycopy(src, i, dst, + 1, src.length - i);     return dst; } 

but may want specialize method dealing primitive types. mean, generics , arrays don't mix - you'll have troubles int , need use wrapper types:

@test public void testinsertinthemiddle() throws exception {     integer[] in = {3, 5, 12, 8};     integer[] out = target.insertincopy(in, 7, 2);     assertequals(out, new integer[] {3, 5, 7, 12, 8}); }