java - Inserts an element into an array and returning the index reallocating the array in case of full array -

i need implement method public int insert (int x) inserts x in "elements" array keeping ordered, , returns index entered; if element present, don't insert x , returns -1; if array full, reallocates "elements" array in array of double size , insert item x. know there similar methods in api rather implement it.

i wrote this, not know how complete it...

public int insert(int x)  {     if(numelements == elements.length) {                 //code             }        int pos = binarysearch(x);     if(pos != -1)          return -1;     if(elements[-(pos + 1)] != null) {         for(int = numelements; >= -(pos + 1); i--)             elements[i + 1] = elements[i];     }     elements[-(pos + 1)] = x;     numelements++;     return -(pos + 1); } 

i not know if wrote correct, however, , miss case of full array. can me? thanks

---

private int binarysearch(int x) {     int inf = 0;     int sup = numelements - 1;     if(sup == -1 || elements[0] > x)         return -1;     if(elements[sup] < x)         return -(numelements + 1);     //invariante di ciclo: se x in a, allora x in a[inf...sup]     while(inf <= sup) {         int = (inf  + sup) >>> 1; //divide per due         if(elements[i] > x)             sup = - 1;         else if(elements[i] < x)             inf = + 1;         else             return i;     }     return -(inf + 1); } 

here go.

what did create new array twice size , use system.arraycopy move existing elements. lastly assigned reference of enlarged array elements variable.

i used system.arraycopy because faster manually made loop-copy. using native implementation jvm.

also replaced check array displacement , loop system.arraycopy. also, -(pos + 1) gives negative number.

public int insert(int x)  {     if(numelements == elements.length) {          int[] enlargedelements = new int[elements.length * 2];          system.arraycopy(elements, 0, enlargedelements, 0, elements.length);          elements = enlargedelements;     }        int pos = binarysearch(x);     if(pos == -1)          return -1;     if(pos < numelements) {         system.arraycopy(elements, pos, elements, pos + 1, numelements - pos);     }     elements[pos] = x;     numelements++;     return pos; }  private int binarysearch(int x) {     int inf = 0;     int sup = numelements - 1;     if(sup == -1 || elements[0] > x)         return 0;     if(elements[sup] < x)         return numelements;     //invariante di ciclo: se x in a, allora x in a[inf...sup]     while(inf <= sup) {         int = (inf  + sup) >>> 1; //divide per due         if(elements[i] > x)             sup = - 1;         else if(elements[i] < x)             inf = + 1;         else             return -1;     }     return inf; }