1.请将”我” “爱” “中”“国”存入数组,然后正着和反着输出
public static void main(String[] args) { print(); } public static void print() { //创建一个数组 String[] arr = new String[]{"我", "爱", "中", "国"}; int index = 0; for (int i = 0; i < arr.length; i++) { System.out.print(arr[i]); } System.out.println(); for (int i = arr.length - 1; i < arr.length; i--) { if (i < 0) { break; } System.out.print(arr[i]); } }
运行结果:
2.定义一个长度为10的整型数组,循环输入10个整数。 然后将输入一个整数,查找此整数,找到 输出下标,没找到给出提示。 ?
public static void main(String[] args) { int[] arr = new int[10]; Scanner sc = new Scanner(System.in); System.out.println("请输入10个数"); int index = 0; for (int i = 0; i < arr.length; i++) { arr[i] = sc.nextInt(); } while (true) { System.out.println("请输入要查找在的数"); int a = sc.nextInt(); for (int i = 0; i < arr.length; i++) { if (a == arr[i]) { index = i; System.out.println("该数的下标为:" + index); return; } } System.out.println("没有您需要查找的数字"); } } }
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?3.求一个3*3矩阵对角线元素之和,要求矩形里面的值为随机赋值
public static void main(String[] args) { int[][] arr = new int[3][3]; Scanner sc = new Scanner(System.in); for (int i = 0; i < arr.length; i++) { for (int j = 0; j < arr[i].length; j++) { System.out.println("请输入数组中arr[" + i + "][" + j + "]" + "的值:"); arr[i][j] = sc.nextInt(); } } System.out.println("您输入的二维数组元素是:"); for (int i = 0; i < arr.length; i++) { for (int j = 0; j < arr[i].length; j++) { System.out.print(arr[i][j] + " "); } System.out.println(); } int sum = 0; for (int i = 0; i < arr.length; i++) { for (int j = 0; j < arr[i].length; j++) { if (i == j && i + j != 2 || i + j == 2) { sum += arr[i][j]; } } } System.out.println("您输入的二维数组对角线元素之和是:" + sum); sc.close(); } }
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4.自定义一个字符串数组,提示用户输入5个字符串,通过循环语句实现将用户输入的字符串存放到数
组里,然后反向输出这五个字符串。
public static void main(String[] args) { int[] arr = new int[5]; Scanner sc = new Scanner(System.in); for (int i = 0; i < arr.length; i++) { System.out.println("请输入数组中arr[" + i + "]的值:"); arr[i] = sc.nextInt(); } System.out.println("您输入的数组元素是:"); for (int i = 0; i < arr.length; i++) { System.out.print(arr[i] + " "); } System.out.println(); System.out.println("反转后的元素:"); for (int j = arr.length - 1; j < arr.length; j--) { if (j < 0) { break; } System.out.print(arr[j] + " "); } } }
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5.打印扑克牌
提示:可定义如下的数组
String[] hs = {"?","?","?","?"};
String[] ds = {"A","2","3","4", "5","6","7","8","9","10","J","Q","K"};
代码实现,效果如图所示:
?A ?2 ?3 ?4 ?5 ?6 ?7 ?8 ?9 ?10 ?J ?Q ?K?
?A ?2 ?3 ?4 ?5 ?6 ?7 ?8 ?9 ?10 ?J ?Q ?K?
?A ?2 ?3 ?4 ?5 ?6 ?7 ?8 ?9 ?10 ?J ?Q ?K?
?A ?2??3 ?4 ?5 ?6 ?7 ?8 ?9 ?10 ?J ?Q ?K?public static void main(String[] args) { String[] hs = {"?", "?", "?", "?"}; String[] ds = {"A", "2", "3", "4", "5", "6", "7", "8", "9", "10", "J", "Q", "K"}; //遍历两个数组打印 for (int i = 0; i < hs.length; i++) { for (int j = 0; j < ds.length; j++) { //拼接字符串 System.out.print( hs[i] + ds[j]); } //换行输出 System.out.println(); } }
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?6.判断数组中的元素值是否对称.
效果展示:java
{1,2,3,4,3,2,1}是否对称:true
{1,2,3,4,5,6,7}是否对称:falsepublic static void main(String[] args) { int[] arr = new int[7]; Scanner sc = new Scanner(System.in); System.out.println("请输入数组中arr的7个值:"); for (int i = 0; i < arr.length; i++) { arr[i] = sc.nextInt(); System.out.print(arr[i] + " "); } boolean flag = true; for (int left = 0, right = arr.length - 1; left <= right; left++, right--) { if (arr[left] != arr[right]) { flag = false; System.out.println("是否对称:" + flag); break; } else { System.out.println("是否对称:" + flag); break; } } } }
运行结果: