Java基础学习:3、数组

1、三种声明方式:

    // 创建一个double数据类型的数组,长度为5
    double array[] = new double[5];
   // 创建int数据类型数组,长度为6 
   int age[] = {12,11,22,32,90,17};

  

数组扩容:

public static void main(String[] args) {
    int[] oldArray = {1, 2, 3, 4};
    Scanner myScanner = new Scanner(System.in);
    do {
      int[] newArray = new int[oldArray.length + 1];
      for (int i = 0; i < oldArray.length; i++) {
        newArray[i] = oldArray[i];
      }
      System.out.println("请输入要要添加元素");
      int addNum = myScanner.nextInt();
      newArray[newArray.length - 1] = addNum;
      oldArray = newArray;
      System.out.println("====newOld扩容后情况====");
      for (int i = 0; i < newArray.length; i++) {
        System.out.println(newArray[i]);
      }
      System.out.println("=====是否继续添加 y/n =======");
      char key = myScanner.next().charAt(0);
      if(key == 'n') {
        break;
      }
    } while(true);

  }

  

 

2、二维数组:

动态初始化:

    // [2]:表示二维数组里面有两个一维数组,[3]:每一个一维数组里面有三个元素
    int arr[][] = new int[2][3];
  arr[1][1] = 8; // 将第一个一维数组里面的第二个元素赋值为8 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(); } }

/** 打印结果
000
080*/

  静态初始化:

  public static void main(String[] args) {
    int[][] arr = {{1,2, 3, 4, 5},{6,7,8,9,10},{11,12,13,14,15},{16,17,18,19,20}};
   // 二维数组里面每一个一维数组个数可以不一致
  int[][]arr2 = {{1,2,3},{4,5},{7,2,23,12}}; 
   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(); } }

  

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posted @ 2021-07-11 18:04  Y字仇杀队  阅读(67)  评论(0编辑  收藏  举报