package cn.test.logan.day04;

import java.util.ArrayList;

/**

 * 编写一个工具类：对整型的Arraylist实现排序、求最大值、最小值、平均值等

 * @author QIN

 *

 */

public class ListUtils {

    // 排序

    public static void sort(ArrayList<Integer> list) {

        for(int i=0;i<list.size()-1;i++) {

            for(int j=0;j<list.size()-1-i;j++) {

                if(list.get(j)>list.get(j+1)) {

                    int tmp = list.get(j);

                    list.set(j, list.get(j+1));

                    list.set(j+1, tmp);

                }

            }

        }

    }

    // 求最大值

    public static int getMax(ArrayList<Integer> list) {

        int tmp = list.get(0);

        for(int i=0;i<list.size();i++) {

            if(list.get(i) > tmp) {

                tmp = list.get(i);

            }

        }

        return tmp;

    }

    public static int getMin(ArrayList<Integer> list) {

        int tmp = list.get(0);

        for(int i=0;i<list.size();i++) {

            if(list.get(i) < tmp) {

                tmp = list.get(i);

            }

        }

        return tmp;

    }

    public static float getAvg(ArrayList<Integer> list) {

        int sum=0;

        for(int i=0;i<list.size();i++) {

            sum+=list.get(i);

        }

        float avg = (float)sum/list.size();

        return avg;

    }

}

package cn.test.logan.day04;

import java.util.ArrayList;

public class ListUtilsTest {

    public static void main(String[] args) {

        // 定义ArrayList

        ArrayList<Integer> aylist = new ArrayList<Integer>();

        aylist.add(30);

        aylist.add(10);

        aylist.add(20);

        aylist.add(50);

        aylist.add(40);

        // 排序

        ListUtils.sort(aylist);

        System.out.println(aylist.toString());

        System.out.println("------------------------------");

        // 求最大值

        int max = ListUtils.getMax(aylist);

        System.out.println(max);

        System.out.println("------------------------------");

        // 求最小值

        int min = ListUtils.getMin(aylist);

        System.out.println(min);

        System.out.println("------------------------------");

        // 求平均值

        float avg = ListUtils.getAvg(aylist);

        System.out.println(avg);

        System.out.println("------------------------------");

    }

}