【java学习笔记】第六章-数组

// 数组练习
public class Array01 {
    public static void main(String[] args) {
        /*
        它们的体重分别是3kg.5kg，1kg，3.4kg，2kg，50kg
        请问这六只鸡的总体重是多少?平均体重是多少?
         */

        // double[] 表示是double 类型的数组， 数组名 heans
        // {3,5,1,3.4,2,50} 表示数组的值或元素，依次表示数组的第几个元素
        double[] hens = {3,5,1,3.4,2,50};

        double totalWeight = 0;
        // 遍历数组
        for (int i = 0; i < hens.length; i++){
            totalWeight += hens[i];
        }
        System.out.println("总体重为= " + totalWeight + "平均体重为：" + (totalWeight/hens.length));

    }
}

public class one {
    public static void main(String[] args) {
        /*
        创建一个char类型的26个元素的数组，
        分别放置A-Z、使用for访问所有元素并打印出来
         */
        char[] z = new char[26];
        int i = 0;
        for (char n= 'A'; n <= 'Z'; n++){
            z[i] = n;
            i++;
        }
        for (int a = 0; a < z.length; a ++){
            System.out.print(z[a]);
        }
    }
}

public class one {
    public static void main(String[] args) {
        /*
        请求出一个数组int[]的最大值[4，-1，9，10，23并得到对应的下标
         */

        int[] ints = {4 , -1 , 9 , 10 , 23 };
        int max = ints[0];
        int maxIndex = 0;

        for (int i = 1; i < ints.length; i++){
            if (max < ints[i]){
                max = ints[i];
                maxIndex = i;
            }
        }
        System.out.println("最大值为" + max + "下标为：" + maxIndex);
    }
}

import java.util.Scanner;
public class one {
    public static void main(String[] args) {
        int[] arr = {1, 2, 3, 4, 5};
        do {
            int[] arr1 = new int[arr.length + 1];
            Scanner myScanner = new Scanner(System.in);
            System.out.println("请输入增加的数");
            int k = myScanner.nextInt();
            for (int i = 0; i < arr.length; i++){
                arr1[i] = arr[i];
            }
            arr1[arr.length] = k;
            arr = arr1;
            for (int i = 0; i < arr.length; i++){
                System.out.print(arr[i]);
            }
            System.out.println("是否继续添加？ y//n");
            char key = myScanner.next().charAt(0);
            if (key == 'n'){
                break;
            }
        }while (true);
    }
}

import java.util.Scanner;
public class one {
    public static void main(String[] args) {
        int[] arr = {1 ,2 ,3 ,4 ,5};
        while (true){
            int[] arr1 = new int[arr.length - 1];
            System.out.println("对数组进行缩减!");
            for (int i = 0; i < arr.length - 1; i++){
                arr1[i] = arr[i];
            }
            arr = arr1;
            for (int i = 0; i < arr.length; i++){
                System.out.print("缩减后的数组为" + arr[i] + "\t");
            }
            if (arr.length == 1){
                System.out.println("不能继续缩减了，推出程序了哦");
                break;
            }
            Scanner myScanner = new Scanner(System.in);
            System.out.println("是否继续缩减 y/n");
            char key = myScanner.next().charAt(0);
            if (key == 'n'){
                break;
            }
        }

    }
}