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Settext of EditText from another class gives nullpointer
public class RoundCommentDialog extends Dialog implements View.OnClickListener {

    private Context context;

    private String roundCommentText;
    private EditText roundCommentEditText;

    private Button postiveButton;
    private Button negativeButton;

    public RoundCommentDialog(Context context) {
        super(context);
    }

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.custom_round_comment_dialog);

        postiveButton = (Button) findViewById(R.id.dialog_positive_button);
        postiveButton.setOnClickListener (this);
        negativeButton = (Button) findViewById(R.id.dialog_negative_button);
        negativeButton.setOnClickListener (this);

        roundCommentEditText = (EditText) findViewById(R.id.comment_text);

    }

    public void setRoundCommentText(String roundCommentText) {
        this.roundCommentText = roundCommentText;
    }

    public String getRoundCommentText() {
        return roundCommentEditText.getText().toString();
    }

    public void updateCommentEditField() {

        roundCommentEditText.setText("TEST");
    }

    public Dialog getDialog() {
        updateCommentEditField();
        return this;
    }

    public void onClick(View v) {
        switch (v.getId()) {
        case R.id.dialog_positive_button:

            setRoundCommentText(roundCommentText);

            dismiss();
            break;
        case R.id.dialog_negative_button:
            cancel();
            break;
        }

    }


}

RoundCommentDialog myDialog = new RoundCommentDialog(this);

myDialog.setRoundCommentText(roundComentText);
myDialog.getDialog().show();

roundCommentEditText.setText("TEST");

private String roundCommentText;

public String roundCommentText;