Thread: Matrix Program

I was writing a simple Java program to input a matrix and then display it using 2-dimensional arrays. I used the same logic which I had previously used for the same program in C. But it isn't working. It goes on taking taking values until the index goes out of bound and then displays an error :

"Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 4
at apples.main(apples.java:136)"

The line 136 is: a[i][j] = mad.nextInt(); in bold below

import java.util.Scanner;

class apples{
public static void main(String args[]){
int a[][] = new int[4][4];
int m,n;
Scanner mad = new Scanner(System.in);

System.out.println("Enter the order");
m = mad.nextInt();
n = mad.nextInt();
System.out.println("Order is " + m + "x" + n);
System.out.println("Enetr the elements");
for(int i=0;i<m;i++){
for(int j=0;i<n;j++){
a[i][j] = mad.nextInt();
}
}
System.out.println("The matrix is");
for(int i=0;i<m;i++){
for(int j=0;i<n;j++){
System.out.println(a[i][j]);
System.out.println("\t");
}
System.out.println();
}

}
}

Are there other methods of doing this. The user has to give the input for the matrix and then it should be displayed.


Thank you,

hmmmm......

how about try changing your for loops:

for(int i=0;i<4;i++){
for(int j=0;i<4;j++){
a[i][j] = mad.nextInt();
}
}

Few edits are there to run the program correctly------------


import java.util.Scanner;

class apple{
public static void main(String args[]){
int a[][] = new int[4][4];
int m,n;
Scanner mad = new Scanner(System.in);

System.out.println("Enter the order");
m = mad.nextInt();
n = mad.nextInt();
System.out.println("Order is " + m + "x" + n);
System.out.println("Enetr the elements");
for(int i=0;i<m;i++){
for(int j=0;j<n;j++){
a[i][j] = mad.nextInt();
}
}
System.out.println("The matrix is");
for(int i=0;i<m;i++){
for(int j=0;j<n;j++){
System.out.print(a[i][j]);
}
System.out.println();
}

}
}



the major mistake is in the loops!!