Here is the code for shacker sort or bidirectional bubble sort. Something is wrong. Error is

java.lang.ArrayIndexOutOfBoundsException

Can anybody help me?

public class bidirectional{

  public static void main(String[]args){

    int x[]=new int[]{12,9,4,99,120,1,3,10};
    int j;
    int n=x.length;
    int st=-1;

    while (st<n){
      st++;
      n--;
      for (j=st;j<n;j++){
        if (x[j]>x[j+1]){
          int t=x[j];
          x[j]=x[j+1];
          x[j+1]=t;
        }
      }

      for (j=n;--j>=st;){

        if (x[j]>x[j+1]){
          int t=x[j];
          x[j]=x[j+1];
          x[j+1]=t;
        }
      }
    }

    for (int k=0;k<x.length;k++){
      System.out.println(x[k]);
    }
  }
}

thanks i have got result thanks guys i have accepted all answers