Static and dynamic initialization of one-dimensional, two-dimensional arrays in Java

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

Array Overview:

The array can be regarded as a combination of multiple identical types of data, and the unified management of these data;

An array variable is a reference data type, and an array can be considered an object, and each element in the array is equivalent to the member variable of that object;

The elements in the array can be any data type, including the base data type and the reference data type;

Declaration of one-dimensional array:

Way of declaring: for example; int a [] = new int [3];

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

unlawful declaration; int a [5];

Creation of Array objects:

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 [] = {n/a};

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 arrays

A two-dimensional array can be considered an array of elements, such as:

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}}; Illegal

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];

Static and dynamic initialization of one-dimensional, two-dimensional arrays in Java