java二分法查找

import java.util.ArrayList;
import java.util.List;


/**
 * 二分法查找
 * 
 * @author ZHao
 * 
 */
public class Test {
static List<Integer> numlst = new ArrayList<Integer>();


public static void main(String[] args) {
for (int i = 1; i <= 34320; i++) {
numlst.add(i);
}
System.out.println(count(34321, numlst));
}


public static int count(int needSearchNumber, List<Integer> numbers) {
if (needSearchNumber > numbers.get(numbers.size() - 1)) {
return -1;
}
int index = 0;
int front = 0;
int end = numlst.size() - 1;
while (front <= end) {
int mid = (front + end) / 2;
// 大于
if (needSearchNumber > numbers.get(mid)) {
front = mid + 1;
}
// 小于
else if (needSearchNumber < numbers.get(mid)) {
end = mid - 1;
}
// 等于
else {
index = mid;
break;
}
}
return index;
}
}