An analysis of the Java array-Basic explanation

What is an array: An array is one of the most important data structures for every programming language, and the implementation and processing of arrays of different languages are not identical.

Java array: Used to store the same type elements of a fixed size.

A declaration, creation, initialization of a Java array

Write in front: Defining a Java array includes declaration and creation: it can be declared, then created (two steps), or it can be declared and created at the same time (one step).

1. Disclaimer

Method 1 (preferred):dataType[] arrayname; Example: string[] country;

Method 2:dataType arrayname[];: example: String country[];

< Span class= "hl-brackets" > 2. Create

< Span class= "hl-brackets" > method: Arrayname = new Datatype[arraysize];&NBSP;

Explanation: An array was created using datatype[arraysize]. Assigns a reference to the newly created array to the variable arrayname.

Example: Country=new string[4]; Creates an array with a type of String, an array length of 4, and assigns a reference to the array to country;

3. Simultaneous declaration and creation

Method:dataType[] arrayname= new dataType[arraySize]; Example: string[] Country=new STRING[4];

4. Initializing an array

Method 1:datatype[] arrayname= new type[]{value1,value2,value3,......}; The red part can be saved slightly, so there are two kinds:

Example 1:string[] Country = {"China", "America", "England", "Japan"}

Example 2:string[] Country = new String[]{"China", "America", "England", "Japan"}

The array length cannot be added to [] in Example 2, because the number of elements is determined by the contents of the following curly braces.

Method 2: Create the array first, then assign the values separately, i.e. DataType[] arrayname= new dataType[arraySize];arrayname[0 ]=value1;......arrayname[arraysize-1]=value;

Example: string[] country=new string[4]; Country[0]= "China"; Country[1= "America"; country[2]= "England"; country[3]= "Japan";

Note: The subscript of an array is counted starting at 0, i.e. Arrayname[0] is the first value of the array

Common methods of two arrays

1. Traverse

Method One: For loop, example below

Package Bokeyuan;

public class Arraytest {

public static void Main (string[] args) {
/* Example 1*/
string[] Country = new string[]{"China", "America", "England", "Japan"};
for (int i=0;i<country.length;i++) {
System.out.print (country[i]+ ""); Output: China America England Japan
}

/* Example 2*/
Int[] MyNum = {1,2,3,4,5,6,7,8,9,10};
int numcount=0;
for (int i=0;i<mynum.length;i++) {
Numcount+=mynum[i];
System.out.print (mynum[i]+ ""); Output results: 1 2 3 4 5 6 7 8 9 10
}
System.out.println (Numcount); Output results: 55
}

}

Method 2:foreach traversal, as shown below

        /*Example 1*/string[] Country=Newstring[]{"China", "America", "England", "Japan"};  for(String element:country) {System.out.print (element+" ");//output: China America England Japan        }        /*Example 2*/        int[] MyNum = {1,2,3,4,5,6,7,8,9,10}; intNumcount=0;  for(intNum:mynum) {//where num is a temporary variable that is used to receive data and can be written as any other valid identifier; Aaa,elenumcount+=num; System.out.print (Num+" ");//Output Results: 1 2 3 4 5 6 7 8 9} System.out.println (Numcount); //Output Result:

　　　　　　

An analysis of the Java array-Basic explanation