matrix array

[dejie lin]

hi all,
i have defined a class "matrix" by my self, i wanna have an array of matrix, the code is in the following:
....
matrix[][] m=new matrix[20][15];
for(int i=0;i<20;i++)
for(int j=0;j<20;j++)
m[i][j] = new matrix();
....
class matrix
{
public int type;
public int NodeNo;
public matrix()
{
type=0;
NodeNo =0;
}
void settype(int t)
{
type =t;
}
void setNodeNo(int n)
{
NodeNo =n;
}
}
Problem : there's no compiling error, but there will be arrayIndexOutOfBoundsException ....
Anybody can help me?
thanks
dejie

[Ashish Hareet]

Hi Dejie,
j will max out at 14 so j < 20 is gonna throw an exception, it should read j < 15.
A better approach would be -

matrix[][] m = new matrix[20][15] ;
        for(int i=0 ; i < m.length ; i++)
            for(int j=0 ; j < m[i].length ; j++)
                m[i][j] = new matrix() ;

I don't think I have got this wrong, but do check, no JVM on this machine.
HTH
Ashish Hareet