Java入门第三季_随机字符串排序

// 对各种类型的List进行排序

package com.imooc.collection;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Random;

public class CollectionsTest {

// sortList()
public void sortList() {
    // 基本类型做泛型要使用包装类
    List<Integer> integerList = new ArrayList<Integer>();
    Random random = new Random();
    Integer k;
    // 10个100以内不重复整数
    for (int i=0;i<10;i++) {
        do {k = random.nextInt(100);} while (integerList.contains(k));      
        integerList.add(k);
    }
    System.out.println("添加成功：10个100以内不重复整数");
    // 未排序前
    System.out.print("未排序前：");
    for (Integer integer : integerList) System.out.print(integer+" ");
    // 排序之后
    System.out.print("\n排序之后：");
    Collections.sort(integerList);
    for (Integer integer : integerList) System.out.print(integer+" ");
}

// sortString()    0-9 A-Z a-z
public void sortString() {
    List<String> sl = new ArrayList<String>();
    sl.add("Apple");
    sl.add("Nike");
    sl.add("Google");
    System.out.println("\n添加成功：3个字符串");
    System.out.print("未排序前：");
    for (String string : sl) {
        System.out.print(string+" ");
    }
    Collections.sort(sl);
    System.out.print("\n排序之后：");
    for (String string : sl) {
        System.out.print(string+" ");
    }
}

// sortString() v2
public void homework() {
    List<String> hw = new ArrayList<String>();
    // 10条字符串
    for (int i=0; i<10; i++) {
        // 长度10以内
        String s = "";    // 方法里面的变量要赋初值！！！
        do {
            Random r = new Random();
            int digit = r.nextInt(10);
            for (int j=0; j<digit; j++) {
                // 随机生成字符
                int a = 0;
                do {
                    a = r.nextInt(75)+48;
                } while ( (a>57&&a<65) || (a>90&&a<97) );
                char b = (char) a;
                s+=b;
            } 
        } while (hw.contains(s));
        hw.add(s);
    }
    System.out.println("\n未排序的10个随机字符串：");
    for (String string : hw) System.out.println(string);
    System.out.println("排序后的10个随机字符串：");
    Collections.sort(hw);
    for (String string : hw) System.out.println(string);
}

public static void main(String[] args) {
    CollectionsTest ct = new CollectionsTest();
    ct.sortList();  
    ct.sortString();
    ct.homework();
}

}