CODEWITHSUNDEEP
javastatic
user2158735
user2158735

Reputation: 47

java- method cannot be found from non static

I have 2 classes, dog and printing, the dog class is meant to send over a char[][] to printing so it can print to a printer. However, the dog class can't find the printing method in printing class.

//Printing class-
public class Printing implements Printable, ActionListener {
    String str = "";

    public String printString(char [][] grid ){  
        for(int i=0;i<9;i++){
            for (int j=0;j<9;j++){    
                str += String.valueOf(grid[i][j]);
            }
            str += "\n";
        } 
        return str;
    }
}

I then require this str in another method as well. When I type Printing.printString(grid); it cannot be referenced from static context. When I change it to public static String(char [][] grid ) its method then can't find the str string variable.

Upvotes: 0

Views: 77

Answers (4)

Salah
Salah

Reputation: 8657

You can't call Printing.printString(grid); like this unless you make it a static.

Also if you made printString() method as a static you need to declare str as a static because you cant refer a non-static variables within a static methods.

So you code should look like this:

public class Printing  implements Printable, ActionListener {
static String str = "";

    public String printString(char [][] grid ){  
        for(int i=0;i<9;i++){
            for (int j=0;j<9;j++){    
                str += String.valueOf(grid[i][j]);
            }
            str += "\n";
        } 
        return str;
    }
}

Read more about static variables and methods

Upvotes: 1

Kick
Kick

Reputation: 4923

static String str = "";

 public static String printString(char [][] grid ){  
        for(int i=0;i<9;i++){
            for (int j=0;j<9;j++){    
                str += String.valueOf(grid[i][j]);
            }
            str += "\n";
        } 
        return str;
}

Now you can call the method using Printing.printString(grid);

The non-static instance variable can't be refer in static class and vice versa

Upvotes: 0

WeMakeSoftware
WeMakeSoftware

Reputation: 9162

this will help

public String printString(char [][] grid ){  
     String str = "";

        for(int i=0;i<9;i++){
            for (int j=0;j<9;j++){    
                str += String.valueOf(grid[i][j]);
            }
            str += "\n";
        } 
        return str;
}

Upvotes: 0

RymplEffect
RymplEffect

Reputation: 151

The str member must also be static. Just make sure that you reset it with each call to printString.

  class Printing
  {
    private static String str = "";

    public static printString( char[][] grid )
    {
      str = "";

      for(int i=0;i<9;i++)
      {
        for (int j=0;j<9;j++)
        {
          str += String.valueOf(grid[i][j]);
        }

        str += "\n";
      }

      return str;
    }
  }

Also, this isn't really part of the question, but I recommend the use of the StringBuffer class in situations like this.

Upvotes: 0

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