Methods to implement static and dynamic initialization of one-dimensional and two-dimensional arrays in Java

Today I will share with you arrays in Java through this article, including static initialization and dynamic initialization of one-dimensional arrays and two-dimensional arrays. Friends who are interested should take a look.

Today we are going to start talking about Talk about arrays in Java, including static initialization and dynamic initialization of one-dimensional arrays and two-dimensional arrays

Overview of arrays:

Arrays can be seen It is a combination of multiple data of the same type, and the unified management of these data;

Array variables belong to the reference data type. Arrays can also be regarded as objects. Each element in the array is equivalent to a member of the object. Variable;

The elements in the array can be of any data type, including basic data types and reference data types;

Declaration of one-dimensional array:

Declaration method: For example; int a [ ] = new int [3];

The declaration in Java language cannot specify its length [the number of elements in the array] Number];

Illegal statement; int a [5];

Creation of array object:

public class Test {
　　　public static void main (String args[ ] ) {
　　　　　int [ ] s;
　　　　　s = new int [5];
　　　　　for(int i = 0; i < 5; i ++) {
　　　　　s[i] = 2 * i + 1;
　　　　　}
　　　}
}

One-dimensional array initialization

Dynamic initialization:

public class Test {
　　public static void main (String args [ ] ) {
　　int a [ ];
　　a = new int [3];
　　//int a [ ] = {1,2,3};
　　Date days [ ];
　　days = new Date [3];
　　days [0] = new Date(1,4,20040);
　　days [1] = new Date(2,4,20040);
　　days [2] = new Date(3,4,20040);
　　}
}
class Date {
　　int year,month,day;
　　Date (int y,int m,int d) {
　　　　year = y; month = m; day = d;
　　}
}

Static initialization

public class Test {
　　public static void mian (String args [ ] ) {
　　　　int a[ ] = new int [ ] {3,9,8};
　　　　Date days[ ] = {
　　　　new Date(1,4,2004),
　　　　new Date(2,4,2004),
　　　　new Date(3,4,2004)
　　　　};
　　}
}
class Date {
　　int year,month,day;
　　Date(int y,int m,int d) {
　　　　year = y; month = m;day = d;
　　}
}

Two-dimensional array

Two-dimensional array can be regarded as an array An array of elements, for example:

int a [ ][ ] = {{1,2},{3,4,5,6},{7,8,9}};

Two-dimensional array initialization

Static initialization:

　int intA [ ] [ ] = {{1,2},{2,3},{3,4,5}};
　　int intB [ 3] [ 2] = {{1,2},{2,4},{4,5}};　　非法

Dynamic initialization:

int a [ ] [ ] = new int [3] [5];
　　int b [ ] [ ] = new int [3] [ ];
　　b[0] = new int [2];
　　b[1] = new int [3];
　　b[2] = new int [5];

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