Java数组详解

朴灿烈づ我的快乐病毒、 2022-02-23 05:24 187阅读 0赞

## 声明数组 ##

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## 数组for each循环 ##

有点像python语法：

for(int element : a)
                System.out.println(element);

数组打印:

import java.util.Arrays;
    
    public class array { 
        public static void main(String[] args){ 
            //int[] a;
            int[] a = new int[100];   //创建可以存储100个数字的数组
            for(int i = 0; i < 100; i ++){ 
                a[i] = i;
            }
            for(int i = 0; i < 100; i ++){ 
                System.out.println(a[i]);
            }
            //同样是可以打印的
            for(int element : a)
                System.out.println(element);
    
            System.out.println(Arrays.toString(a));
        }
    }

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## 数组拷贝(浅拷贝、深拷贝) ##

import java.util.Arrays;
    
    public class arrayCopy { 
        public static void main(String[] args){ 
            int[] a = { 17, 19, 23, 29, 31, 37};
            int[] small = a;   //浅拷贝
            small[1] = 33;
            System.out.println(Arrays.toString(a));
            int[] copy = Arrays.copyOf(a, a.length); //深拷贝
            copy[0] = 12;
            System.out.println(Arrays.toString(a));
            System.out.println(Arrays.toString(copy));
        }
    }

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl8zNjM3Mjg3OQ_size_16_color_FFFFFF_t_70 2]  
浅拷贝拷贝的引用：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl8zNjM3Mjg3OQ_size_16_color_FFFFFF_t_70 3]  
深拷贝拷贝的整个数组。

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## Arrays API ##

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## 多维数组 ##

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1.  声明比较简单
2.  如果需要声明固定的二维数组，使用new方法
3.  如果一直元素，可以直接声明

**二维数组也可以使用for each来遍历**

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl8zNjM3Mjg3OQ_size_16_color_FFFFFF_t_70 7]

注意每一行是一个\*\*double\[\]\*\*类型的数据  
也可以使用Arrays.deepToString来将二维数组打印出来

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## 不规则数组 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl8zNjM3Mjg3OQ_size_16_color_FFFFFF_t_70 8]  
可以使用下面的放来先确定行的个数，然后再确定列的个数

int[][] odds = new int[NMAX + 1][]

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