二分查找

package com.wh.ObjectHomeWork;

import java.util.Arrays;

public class CharArray {
    private char[] words;

    public CharArray(char[] words) { // 构造方法
        this.words = words;
    }

    public void sort() { // 对数组进行冒泡排序
        for (int i = 0; i < words.length - 1; i++) {
            for (int j = 0; j < words.length - 1 - i; j++) {
                if (words[j] > words[j + 1]) {
                    char t = words[j];
                    words[j] = words[j + 1];
                    words[j + 1] = t;
                }
            }
        }
    }

    public int search(char key){
        int start=0,ends=words.length-1;
        int middle;
        int index=0;
        for(;;){
            middle=(ends+start)/2+(ends+start)%2;
            if(words[middle]==key){
                index=middle;
                break;
            }else if(key<words[middle]&&key>=words[start]){
                ends=middle;
            }else if(key>words[middle]&&key<=words[ends]){
                start=middle;
            }else{
                index=-1;
                break;
            }
            System.out.print(index+",");
        }        
        return index;
    }

    public static void main(String[] args) {
        char[] arr = "qwertyuiopasdfghjklzxcvbnm".toCharArray();
        CharArray c1 = new CharArray(arr);
        System.out.println("排序前：" + Arrays.toString(arr));
        c1.sort();
        System.out.println("排序后：" + Arrays.toString(arr));
        char num=150;
        int index=c1.search(num);
        System.out.println(index);
    }
}

排序前：[q, w, e, r, t, y, u, i, o, p, a, s, d, f, g, h, j, k, l, z, x, c, v, b, n, m]
排序后：[a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u, v, w, x, y, z]
-1