"Non-static method cannot be referenced from a static context" ?

[Kristian Andersson]

I got a class in which I want to call three methods. The problem is as stated in the subject of this post. I got no clue whatsoever of what I should to to make it work. Anyway, heres the code:

import java.util.*;
public class and_kri {
public static void main(String[] args)
{
String[] array1 = {"woe", "moe", "cloe"};
String[] array2 = {"blip", "blop"};
String[] array3 = {"snap", "lap", "tap"};
String[][] matrix = {array1, array2, array3};

eraseMatrixValues(matrix);

}
public void printMatrix(String[][] matrix) {

for (int f = 0; f < matrix.length; f++)
{
int h = matrix[f].length - 1;
for (int g = 0; g < matrix[f].length; g++)
{
if (g < h)
{
System.out.print(matrix[f][g] + ", ");
}
else if (g == h)
{
System.out.println(matrix[f][g]);
}
}
}
}
public String[][] eraseMatrixValues(String[][] matrix) {
for (int f = 0; f < matrix.length; f++)
{
for (int g = 0; g < matrix[f].length; g++)
{
matrix[f][g] = null;
}
}
return matrix;
}
public String[][] reverseArrayOrder(String[][] matrix) {
String[][] matrix2 = new String[1000][1000];
for (int j = 0; j < 2; j++)
{
int h = 0;
for (int f = matrix.length - 1; f >= 0; f--)
{
int i = 0;
for (int g = 0; g < matrix[f].length; g++)
{
if (j == 0)
{
matrix2[h][i] = matrix[f][g];
}
else if (j == 1)
{
matrix[h][i] = matrix2[h][i];
}
i++;
}
h++;
}
}
return matrix;
}
}
  

Would anyone please tell me what to do?
And if you want to help out further, I would like some help with the method "reverseArrayOrder". The point with this one is, as the name suggests, to reverse the array order. I either need a way to copy the matrix that comes with the method-call, or I need to create an empty matrix with the same size and use this to temporarily store contents of the arrays while moving their contents around. Right? I've thought of using an ArrayList, but I can't come up with a way to make it work...

[Greg T Robertson]

You are attempting to call the eraseMatrixValues from the static method "main". If you did

and_kri and_kri = new and_kri();
and_kri.eraseMatrixValues(matrix);

Reason is that you can't call "non static" methods from a static method. As an alternative you could make the methods all static.
As an aside classes are usually named with the first letter as a capital.
[ May 10, 2004: Message edited by: Greg T Robertson ]

[Gary Down]

I take it you're fairly new to Java (as I am) so I don't want you to get ahead of what you are learning but this looks like a good problem for the "Collections" interfaces.
try reading
http://java.sun.com/docs/books/tutorial/collections/interfaces/index.html
Good Luck,
Gary.

[Ben Cramphorn]

I had this problem when I was working with an object earlier. I kept on getting this error popping up when I kept on trying to write and retrieve data from the class file instead of the object I had created from the class..

Maybe this is what youare doing??

[Ben Baker]

change to public void main(String []args)

insted..... it should run.... Dynamic non static methords can not be static...

[Layne Lund]

Originally posted by I Dispise:
change to public void main(String []args)

insted..... it should run.... Dynamic non static methords can not be static...

Java requires that main() be declared static, so this is not an option. I think other people have given the correct answer, though.

Layne

[Aurelian Tutuianu]

On the other hand you should try to move all the code from main function into something else (for example public void run() {...}).
After you've done this, rewrite the main method:

  
import java.util.*;
public class and_kri {
    public static void main(String[] args) {
        and_kri ak = new and_kri();
        ak.run();
    }
 
    public void run() {
String[] array1 = {"woe", "moe", "cloe"};
String[] array2 = {"blip", "blop"};
String[] array3 = {"snap", "lap", "tap"};
String[][] matrix = {array1, array2, array3};

eraseMatrixValues(matrix);
    }
 
    // the rest is like you allready had
    //....

an alternate solution in respect to change all methods into static.

hope will help.

[Mike Gershman]

I somewhat disagree with Greg's code:

 and_kri and_kri = new and_kri();
and_kri.eraseMatrixValues(matrix);
 

The dual use of the identifier and_kri is correct, but confusing. I guess class names and variable names occupy different name spaces, but I would write:

 AndKri andKri = new AndKri();
andKri.eraseMatrixValues(matrix);