java-array definition-array print-array copy-array sort

Array definition:

1. Declare variables

int[ ] a;

2. Create an array

int[ ] a=new int[100];

3. Array assignment

a)int[ ] smallPrimes={2,3,4,5,7,11,13};`
b)可以用for循环赋值

4. Anonymous functions

new int [ ]{1,2,3,4};
可以用此方法初始化一个数组，无需创建新变量
int smallPrimes=new int[]{1,2,3,4};
这是下列语句的简写形式：
int[] anonymous={1,2,3,4}; 
smallPrimes=anonymous;

Print array

1. for loop traversal
2. for each loop
for (variable: collection) statement
for example:

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

 System.out.println(Arrays.toString(collection));

Array copy

1. Assign an array variable to another array variable, and the two variables point to the same array.
int[] smallPrimes={2,3,4,5,7,11,13};`
int [] a=smallPrimes;
a[5]=12;
2. If you want to copy all the values ​​of an array to a new one To go to an array, use the copyOf method of the Arrays class:

int[] b=Arrays.copyOf(a,a.length);

The second parameter is the length of the new array. This method is usually used to increase the size of the array:

int[] c=Arrays.copyOf(a,2*a.length);

Array sort

Arrays.sort(a);

Reference: Java Core Volume 1 finishing