Examples of initialization and basic manipulation of two dimensional arrays in Java programming
- 2020-04-01 04:20:05
- OfStack
Declaration and initialization of Java two-dimensional arrays
1. A two-dimensional array can be regarded as an array with an array as an element;
2. Two-dimensional arrays in Java should be declared and initialized in the order from high to low dimensions.
Example:
Static initialization:
Array2. Java:
The program code
public class Array2
{
public static void main(String args[]) {
int a[][] = {{1,2},{3,4,5,6},{7,8,9}} ;
for(int i=0 ; i <a.length ; i++) {
for(int j=0 ; j<a[i].length ; j++) {
System.out.println("a[" + i + "][" + j + "]=" + a[i][j]) ;
}
}
}
}
Dynamic initialization:
The program code
public class Array2D
{
public static void main(String args[]) {
int i , j ;
String s[][] ;
s = new String[3][] ;
s[0] = new String[2] ;
s[1] = new String[3] ;
s[2] = new String[2] ;
for(i=0 ; i<s.length ; i++) {
for(j=0 ; j <s[i].length ; j++) {
s[i][j] = new String(" My position is: " + i + "," + j) ;
}
}
for(i=0 ; i<s.length ; i++) {
for(j=0 ; j<s[i].length ; j++) {
System.out.println(s[i][j]) ;
}
}
}
}
About two-dimensional array operations in Java [example] :
public class Lesson{
public static void main(String [] args){
//Declaration of two-dimensional array:
//Data type [][] array name = new data type [length][length];
//Data type [][] array name = {{123},{456}};
/*
int [][] arr = {{123},{456}}; //Defines and assigns a two-dimensional array of two rows and three columns
for(int x = 0; x<arr.length; x++){ //Positioning line
for(int y = 0; y<arr[x].length; y++){ //Locate the number of elements per row
System.out.print(arr[x][y]);
}
System.out.println("/n");
}
*/
int [][] num = new int [3][3]; //Defines a two-dimensional array of three rows and three columns
num[0][0] = 1; //Assign a value to the first element in the first row
num[0][1] = 2; //Assign a value to the second element in the first row
num[0][2] = 3; //Assign a value to the third element in the first row
num[1][0] = 4; //Assign the first element in the second row
num[1][1] = 5; //Assign a value to the second element in the second row
num[1][2] = 6; //Assign a value to the third element in the second row
num[2][0] = 7; //Assign the first element in the third row
num[2][1] = 8; //Assign a value to the second element in the third row
num[2][2] = 9; //Assign a value to the third element in the third row
for(int x = 0; x<num.length; x++){ //Positioning line
for(int y = 0; y<num[x].length; y++){ //Locate the number of elements per row
System.out.print(num[x][y]);
}
System.out.println("/n");
}
}
}
//The array value arr[x][y] indicates that the specified value is row x and column y.
//When using two-dimensional array objects, pay attention to the length represented by the length,
//After the array name, add the length(such as arr.length), which refers to the number of lines (Row).
//Specify the index followed by a length(such as arr[0].length), which refers to the number of elements that the row has, that is, the number of columns.
Let's take another example: two two-dimensional arrays, and combine them into a new two-dimensional array, with the elements being the sum of the corresponding elements of the two arrays. Enter two arrays: {{1,5},{2,3},{6,5}},& noon; {{4, 2}, {2}, {5, 7}}
Output print: {{5,7},{4,9},{11,12}}
Code:
class arraysCtrl{
static void arraysAdd(int[][] a,int[][] b)
{
StringBuffer sbResult = new StringBuffer("{");
int[][] result = new int[a.length][b.length];
for(int i=0;i<a.length;++i)
{
sbResult.append("{");
for(int j=0;j<a[i].length;++j)
{
result[i][j] = a[i][j]+b[i][j];
sbResult.append(result[i][j]);
if(j == a[i].length-1)
{
if(i == a.length-1)
{
sbResult.append("}");
}else{
sbResult.append("},");
}
break;
}
sbResult.append(",");
}
if(i == a.length-1)
{
sbResult.append("}");
break;
}
}
System.out.println(sbResult);
}
public static void main(String[] args) {
int[][] aTst1 = {{1,5},{2,3},{6,5}}, aTst2 = {{4,2},{2,6},{5,7}};
arraysAdd(aTst1,aTst2);
}
}