Java Arrays Tutorial Part2

 

Java arrays Notes  Part-2

👈PART-1

Table of Contents

1. Double Dimensional Array
1. Double Dimensional Array structure
2. Declaration of Double Dimensional Array
3. Initialization of Double Dimensional Array
1.     Direct initialization
2.     Creating array using new
4. Printing   Dimensional Array
5. char Array
6. String Array

 Double Dimensional Array

 In a double dimensional array, values are stored in the form of rows and columns.

2D Array structure:

 

1  is stored at 0, 0  (first row and first col)

2  is stored at 0, 1  (first row and second col)  

3  is stored at 1, 0  (second row and first col)  

4  is stored at 1, 1  (second row and second col)

Declaration of Double Dimensional Array

syntax:

datatype arrayname [rows][cols];

example:  

  int a[][]; 

 

Array can be declared as shown below.

     
int [][]a;
int []a[];

 

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Initialization of Double Dimensional Array

It can be done in two ways -

type1:
 

    int a[][] = {{2,3}, {4,5}}; //direct initialization
 

type2: 

Declaring double dimensional array using new operator and using index position storing array values.

int a[][] = new int[2][2]; 

 a[0][0] = 1;

 a[0][1] = 2; 

 a[1][0] = 3;
 a[1][1] = 4;  

 

if size is not specified, it can any size.

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Printing  DDarray:

a[][] = {{1,2},{3,4}};

System.out.print(a[0][0]);
System.out.print(a[0][1]);
System.out.print("\n");
System.out.print(a[1][0]);
System.out.print(a[1][1]); 

program:

ddarray.java

class DDarray
{
public static void main(String args[]){

int a[][] = {{1,2},{3,4}}; 

System.out.print(a[0][0]);
System.out.print(a[0][1]);
System.out.print("\n");
System.out.print(a[1][0]);
System.out.print(a[1][1]); 
 

}
}

o/p:
---
1 2
3 4

 

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Initialization of Double Dimensional char Array :

char names[4][10] = {{'a','a','a','a'},

                     {'b','b','b'},
                     {'c','c','c','c'},

                     {'d','d','d','d'}

                    };
 

//4 rows, any no. of columns less than 10.

program:

public class DDarray
{
public static void main(String args[]){
char names[][] =  {{'a'},
                   {'b','b'},
                   {'c','c','c'},
                   {'d','d','d','d'}
                    };
                        
for(int i = 0;i<4;i++)
{
System.out.println(names[i]);
}
System.out.println("");
}
}

Declaration of String in Double Dimension Array:

Example-1

String names [3][20] = {{"india"},{"Briton"},{"America"}}; 

names are 3, and length of the name can be max. of 20.
 

Example-2

String names[][] = {{"india","Rupee"},{"France","Euro"},
                    {"Us","dollar"},{"japan","yen"}};
 

public class DDarray1
{
public static void main(String args[]){ 

 

String names[][] = {{"India","Rupee"},

                    {"France","Euro"},
                    {"USA","Dollar"},

                    {"Japan","Yen"}};
 

for(int i=0; i<4; i++)
{
for(int j=0; j<4; j++)
{
System.out.print(names[i][j]+"\t"+names[i][j+1]);
break;
}
System.out.println("");
}
}
}

 o/p:

India    Rupee
France    Euro
USA    Dollar
Japan    Yen

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Practice Questions on Java Arrays:

1. Create cities and capitals arrays. Accept city from keyboard and print its capital.
2. Print names contact numbers in dd array.
3. Create items and prices arrays, calculate total, print all items, prices, total.
4. Take marks and subjects arrays, find the highest marks in which subject.