package ImoocTest;

import java.util.*;
import java.util.ArrayList;

/**
 * 随机生成10个长度10以内的字符串添加进List集合
 * 输出排序前集合元素
 *用Collections.sort(list)排序后再次输出，对比两次结果
 */
public class CollectionsTest {
    public static List<String> slist = new ArrayList<String>();

    /**
     * 随机生成字符串 参数为字符串长度
     * 
     */
    public static String getRandomString(int length) {
        String base = "abcdefghijklmnopqrstuvwxyz0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        Random random = new Random();
        StringBuffer sb = new StringBuffer();
        for (int i = 0; i < length; i++) {
            int number = random.nextInt(base.length());
            sb.append(base.charAt(number));
        }
        return sb.toString();
    }

    /**
     * 遍历显示集合
     */
    public void listShow() {
        for (String string : slist) {
            System.out.println(string);
        }

    }

    /**
     * 调用getRandomString()方法生成长度随机10以内的字符串10个 将字符串保存进List集合中
     * 
     */
    public void stringListTest() {
        String aString;
        for (int i = 0; i < 10; i++) {
            do {
                Random random = new Random();               
                 int length = random.nextInt(9)+1;
                // 上面语句字符串长度为1-10，下面语句为0到10，可能出现空字符串
                 //int length = random.nextInt(10);
                aString = getRandomString(length);
            } while (slist.contains(aString));
            slist.add(aString);
        }
    }

    public static void main(String[] args) {
        CollectionsTest cTest = new CollectionsTest();
        cTest.stringListTest();
        System.out.println("排序前数组元素");
        cTest.listShow();
        Collections.sort(slist);
        System.out.println("排序后数组元素");
        cTest.listShow();
    }
}