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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