public void binarySearch(int value){
	int low = 0;
	int upper = nElements - 1;
	int currtIn = (low+upper)/2;
	while(true){
		if(array[currtIn] == value){
			System.out.println("find it :_"+currtIn+" "+array[currtIn]);
			return;
		}else if(array[currtIn] > value){//若當前值比關鍵字大，說明關鍵字在其前，upper要變為當前下標-1
			upper = currtIn-1;	
		}else{
			low = currtIn+1;
		}
		if(low>upper){
			System.out.println("can`t find it :"+value);
			return;
		}
		currtIn = (low+upper)/2;
	}
}

遞迴實現：
public void recBinarySearch(int value,int low,int upper){
        int current = (low+upper)/2;
        if(array[current] == value){
            System.out.println("find it:"+current+" value:"+array[current]);
            return;
        }else if(low > upper){
            System.out.println("can`t find it");
        }else{
            if(value > array[current]){
                recBinarySearch(value, current+1,upper);
            }else{
                recBinarySearch(value, low, current-1);
            }
        }
    }