What are the formats for defining arrays in java?

The format for defining arrays in java is: 1. [int[] arr = new int[5]]; 2. [int[] arr = new int[]{1,2,3,4, 5}]. In the Java language, the length (the number of elements in the array) cannot be specified when declaring an array.

The definition format of arrays is as follows:

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When defining an array, the declaration and space initialization are usually written together, as follows:

int[] arr = new int[5];
int arr[] = new int[5];  //不推荐
int[] arr = new int[]{3,1,2,5,6}
int[] arr = {3,1,2,5,6}

Example:

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The following is a way to only declare an array, but not initialize it:

 // 声明整型数组
 int[] intArray0 ;
 int intArray1 [];
 // 声明浮点型数组
 float floatArray0 [];
 float[] floatArray1 ;
 // 声明布尔型数组
 boolean boolArray0 [];
 boolean[] boolArray1 ;
 // 声明字符型数组
  char charArray0 [];
 char[] charArray1 ;
 // 声明字符串数组
 String stringArray0[];
 String[] stringArray1;
 // 错误的声明数组的方式，声明数组的时候不能指定其大小
 // int [5] intErrorArray0;
  // int intErrorArray1[5];

Note: When declaring an array in Java language, you cannot specify its length (the number of elements in the array ).

This is because the array is a reference type variable, so when you use it to define a variable, it only means that a reference variable is defined (that is, a pointer is set). This reference variable also It does not point to any valid memory, so the length of the array cannot be specified when defining the array.

And since defining an array only defines a reference variable and does not point to any valid memory space, there is no memory space to store the array elements, so this array cannot be used until the array is initialized. can use.

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