二分查找法 java

public class Erfen
{
public static int erfen(int a[], int key)
{
int start = 0;
int end = a.length;
while (start < end)
{
int mid = (start + end) / 2;

if (key == a[mid])
{
System.out.println("@@");
return mid;

}
else if (key < a[mid])
{
end = mid - 1;
System.out.println(mid + "$$" + end);
}
else
{
start = mid + 1;
System.out.println("&&");
}
}
return -1;

}

public static int digui(int a[], int start, int end, int key)
{
if (start < end)
{
int mid = (start + end) / 2;
if (key == a[mid])
{
return mid;
}
else if (key < a[mid])
{
digui(a, start, mid - 1, key);
}
else
{
digui(a, mid + 1, end, key);
}
}

return -1;
}

public static void main(String[] args)
{
int[] a = { 1, 2, 3, 6, 8, 9 };
System.out.println(a.length);
int re = Erfen.erfen(a, 6);
System.out.println(re);

int ret = Erfen.digui(a, 0, 6, 6);
System.out.println(ret);
}

}