How to implement array declaration and initialization in Java

Declaration method of one-dimensional array:
type var[]; or type[] var;

The length (the number of elements in the array) cannot be specified when declaring an array,

Use the keyword new in Java to create an array object, the format is:
Array name = new Type of array element [number of array elements]

Example:
TestNew.java:

Program code:

public class TestNew  {       public static void main(String args[]) {           int[] s ;           int i ;           s = new int[5] ;           for(i = 0 ; i < 5 ; i++) {               s[i] = i ;           }           for(i = 4 ; i >= 0 ; i--) {               System.out.println("" + s[i]) ;           }       }   }

Initialization:

1. Dynamic initialization: Array definition is performed separately from the operations of allocating space and assigning values ​​to the array;
2. Static Initialization: Allocate space and assign values ​​to the array elements while defining the number;
3. Default initialization: The array is a reference type, and its elements are equivalent to the member variables of the class. Therefore, after the array allocates space, each element is also Initialized by hermit according to the rules of member variables.
Example:

TestD.java(dynamic):

Program code:

public class TestD  {       public static void main(String args[]) {           int a[] ;           a = new int[3] ;           a[0] = 0 ;           a[1] = 1 ;           a[2] = 2 ;           Date days[] ;           days = new Date[3] ;           days[0] = new Date(2008,4,5) ;           days[1] = new Date(2008,2,31) ;           days[2] = new Date(2008,4,4) ;       }  }   class Date  {       int year,month,day ;       Date(int year ,int month ,int day) {           this.year = year ;           this.month = month ;           this.day = day ;       }  }

TestS.java(static):

Program code:

public class TestS     {          public static void main(String args[]) {              int a[] = {0,1,2} ;              Time times [] = {new Time(19,42,42),new Time(1,23,54),new Time(5,3,2)} ;          }     }      class Time     {          int hour,min,sec ;          Time(int hour ,int min ,int sec) {              this.hour = hour ;              this.min = min ;              this.sec = sec ;          }     }

TestDefault.java (default):

Program code:

public class TestDefault     {          public static void main(String args[]) {              int a [] = new int [5] ;              System.out.println("" + a[3]) ;          }     }

The above is the detailed content of How to implement array declaration and initialization in Java. For more information, please follow other related articles on the PHP Chinese website!