How to initialize java array

Arrays in Java language must be initialized before they can be used. The so-called initialization is to allocate memory space for the array elements of the array and attach an initial value to each array element.

Note: After the array is initialized, there is a default value for each element of the array in the memory space:

Integer type of basic data type (byte, short, int, long) The default value is 0;

The default value of the floating point type of the basic data type (float, double) is 0.0;

The default value of the character type of the basic data type (char) The value is '\u0000';

The Boolean type of the basic data type (boolean), the default value is false; The

type of reference type (class, array, interface, String) default value is null.

Initialization method:

1. Static initialization: During initialization, the programmer explicitly specifies the initial value of each array element, and a system determines the value of the array. length.

1.arrayName = new type[]{element1,element2,element3...}

Example:

int[] intArr;
intArr = new int[]{1,2,3,4,5,9};

2.Simplified static Initialization method: type[] arrayName = {element1,element2,element3...};

Example:

String[] strArr = {"张三","李四","王二麻"};

2. Dynamic initialization: The programmer specifies the size of the array during initialization Length, a default value initialized by the system for each array element.

arrayName = new type[length];

Example:

int[] price = new int[4];

Note: Do not use static initialization and dynamic initialization at the same time, that is, do not specify both the length of the array and each array element when initializing the array. Assign initial value.

Once the array is initialized, the space occupied by the array in memory will be fixed, so the length of the array cannot be changed.

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