Array 数组操作

古城微笑少年丶 2022-10-21 03:44 183阅读 0赞

# 系列文章目录 #

[Array 数组操作][Array]  
[Linked List 链表操作][Linked List]  
[Stack 栈操作][Stack]

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# 前言 #

本文简单介绍了如何利用Java自带的类创建数组，掌握这些将有助于在Leetcode中刷题。

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## Java ##

1.  创建数组
    
        int[] a = {
              1, 2, 3};
        
        int[] b = new int[]{
              1, 2, 3};
        
        int[] c = new int[3];
        for (int i = 0; i < a.length; i++) {
              
            c[i] = i + 1;
        }
        
        ArrayList<Integer> arr = new ArrayList<>();
        for (int i = 0; i < 3; i++) {
              
            arr.add(i + 1);
        }
2.  添加元素
    
        arr.add(99);
        arr.add(3, 88);		// 在索引为3的位置添加元素88
3.  访问元素
    
        int c1 = c[1];
        int arr1 = arr.get(1);
4.  更新元素
    
        c[1] = 11;
        arr.set(1, 11);
5.  移除元素
    
        arr.remove(3);	// 删除元素3
6.  数组长度
    
        int cSize = c.length;
        int arrSize = arr.size();
7.  遍历数组
    
        for (int i = 0; i < c.length; i++) {
              
            int current = c[i];
        }
        
        for (int i = 0; i < arr.size(); i++) {
              
            int current = arr.get(i);
        }
8.  查找元素
    
        for (int i = 0; i < c.length; i++) {
              
            if (c[i] == 99) {
              
                System.out.println("We found 99 in c");
            }
        }
        
        boolean is99 = arr.contains(99);
9.  数组排序
    
        c = new int[]{
              2, 3, 1};
        Arrays.sort(c);
        
        arr = new ArrayList<>{
              };
        arr.add(2);
        arr.add(3);
        arr.add(1);
        Collections.sort(arr);		// 从小到大
        Collections.sort(arr, Collections.reverseOrder());	// 翻转，从大到小
10. 打印数组  
    System.out.println(array); 这样是不行的，这样打印是的是数组的首地址
    
    1.  一维数组
        
            int[] array = {
                    1, 2, 3, 4, 5};
        
        1.  for 循环
            
                for (int i = 0; i < array.length; i++) {
                          
                	System.out.println(array[i]);
                }
        2.  for each
            
                for (int a : array) {
                          
                	System.out.println(a);
                }
        3.  Arrays的toString()  
            调用Array.toString(a)，返回一个包含数组元素的字符串，这些元素被放置在括号内，并用逗号分开
            
                System.out.println(Arrays.toString(array));
    2.  二维数组
        
            int[][] arrays = {
                    
                {
                    16, 3, 2, 13},
                {
                    5, 10, 11, 8},
                {
                    9, 6, 7, 3}
            };
        
        1.  for 循环
            
                for (int i = 0; i < arrays.length; i++) {
                          
                    for (int j = 0; i < arrays[0].length; i++) {
                          
                        System.out.print(array[i][j] + " ");
                    }
                	System.out.println();
                }
        2.  for each
            
                for (int[] a : arrays) {
                          
                	for (int b : a) {
                          
                        System.out.print(b + " ");
                	}
                    System.out.println();
                }
        3.  Arrays的toString()
            
                for (int i = 0; i < array.length; i++) {
                          
                	System.out.println(Arrays.toString(arrays[i]));
                }

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# 总结 #

参考资料来源：[手把手带你刷Leetcode力扣][Leetcode]

[Array]: https://blog.csdn.net/weixin_45118180/article/details/116377659
[Linked List]: https://blog.csdn.net/weixin_45118180/article/details/116377977
[Stack]: https://blog.csdn.net/weixin_45118180/article/details/116378036
[Leetcode]: https://www.bilibili.com/video/BV1sy4y1q79M?p=6