variable accessed within inner class

Question

I have the following code to use to execute a root command:

public static String sudo(final String cmd, Context ctx) {
    String output = null;  //init string output
    if (RootTools.isRootAvailable()) {
        if (RootTools.isAccessGiven()) {
            try {
                CommandCapture command = new CommandCapture(0, cmd) {
                    @Override
                    public void output(int id, String line) {
                        Log.d("com.vwade79.aokpdelta.Functions.sudo", "cmd:"+cmd+"\noutput:"+line);
                        if (line.equals("")) {
                            return;
                        }
                        else {
                            output = line;  //ERROR
                        }
                    }
                };
                RootTools.getShell(true).add(command).waitForFinish();
            } catch (Exception e) {
                Toast.makeText(ctx, "There was an error executing root command : "+cmd, Toast.LENGTH_LONG).show();
                e.printStackTrace();
            }
        }
        else {
            Toast.makeText(ctx, "Root permission isn't given!", Toast.LENGTH_LONG).show();
            Intent intent = new Intent(ctx, MainActivity.class);
            ctx.startActivity(intent);
        }
    }
    else {
        Toast.makeText(ctx, "You're not rooted! Come back when you are!", Toast.LENGTH_LONG).show();
        Intent intent = new Intent(ctx, MainActivity.class);
        ctx.startActivity(intent);
    }
    return output;
}

I am getting an error:

variable "output" is accessed from within inner class. Needs to be declared final.

I don't know how to assign the output from the "inner class".

Answer 1

The error message says it all: you can only access final variables from within an inner class.

A quick solution would be to define:

final String output[] = new String[1];  //init string output

and in the inner class:

                        output[0] = line;  // No ERROR :-)

and then:

return output[0];

This is, because the array itself is final, but the contents of the array can still be changed (a little strange definition of final in Java, if you ask me; final does not mean immutable).