Binary Search

public class BSearch {
    int [] array={1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20};
    int n;
    int key;
  public BSearch(){
      //this.key=key;
     // array={1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20};
      n=array.length;

  }
  public int serch(int key){
     return serch(key,0,n-1);
  }

    public int serch(int key,int s, int e) {
        int mid=(s+e)/2;
       if(e<s){return -1;}
      
       else if(key==array[mid]){return mid;}

        else if(key<array[mid]){return serch(key,s,mid-1);}
    else{return serch(key,mid+1,e);}
    }
public void print(int key){
    System.out.println("index of "+key+"  =   "+serch(key));
  
}
public static void main(String[] a){
BSearch s1=new BSearch();
s1.print(20);
}
}