How to get a view id created programmatically in another class?

Question

I want to find the id of a view created programmatically from a runnable set in another class and passed to the searched view's class.

The idea is to lock an application as long as the right password isn't inputed. So when on the main menu the user press "Unlock" button which prompt an overlay dialog from ViewDialog class. showUnlockDialog() from ViewDialog is the function creating and adding a password EditText to a basic dialog set in R.layout.custom_dialog. The user enters the password and click the button which run the runnable fetching the EditText content to retrieve the password entered.

public class MainMenu extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {

        ....

        Runnable runnable;
        View v;

        runnable = new Runnable(){
            public void run(){
                Runnable runnable = new Runnable(){
                    public void run(){
                        EditText mdp = findViewById((int)1);
                        Log.d("test", mdp.getText().toString());
                    }
                };
                ViewDialog alert = new ViewDialog();
                alert.showUnlockDialog(MainMenu.this, runnable);
            }
        };

        v = findViewById(R.id.button);
        v.setOnClickListener(new Button.OnClickListener(){
            @Override
            public void onClick(View v) {
                runnable.run();
            }
        });

        ....
    }
}

public class ViewDialog extends AppCompatActivity{
    Button positiveButton;
    Button negativeButton;

    ....

    public void showUnlockDialog(Activity activity, Runnable callback){
        final Dialog dialog = new Dialog(activity);
        dialog.setCancelable(true);
        dialog.setContentView(R.layout.custom_dialog);

        ....

        ConstraintLayout constraintLayout = new ConstraintLayout(activity);
        ConstraintLayout.LayoutParams params = new ConstraintLayout.LayoutParams(ConstraintLayout.LayoutParams.MATCH_PARENT, ConstraintLayout.LayoutParams.WRAP_CONTENT);
        constraintLayout.setLayoutParams(params);

        EditText password = new EditText(activity);
        password.setId((int)1);

        constraintLayout.addView(password);

        LinearLayout layout = (LinearLayout) dialog.findViewById(R.id.customDialogLinLayout);
        layout.addView(constraintLayout);

        setDialog1Button(activity, dialog, callback);

        dialog.show();
    }

    public void setDialog1Button(Activity activity, final Dialog dialog, final Runnable callback){
        positiveButton = new Button(activity);
        positiveButton.setText("OK");

        positiveButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if(callback != null) {
                    callback.run();
                }
                dialog.dismiss();
            }
        });

        LinearLayout layout = (LinearLayout) dialog.findViewById(R.id.customDialogLinLayout);
        layout.addView(positiveButton);
    }

    ....
}

When clicking the validation button, password is null in

    EditText password = findViewById((int)1);
    Log.d("test", password.getText().toString());

and the following error is prompted :

E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.megacom.inventaire, PID: 18759
    java.lang.NullPointerException: Attempt to invoke virtual method 'android.text.Editable android.widget.EditText.getText()' on a null object reference
        at com.megacom.inventaire.MainMenu$1$1.run(MainMenu.java:55)
        at com.megacom.inventaire.ViewDialog$1.onClick(ViewDialog.java:107)
        at android.view.View.performClick(View.java:5610)
        at android.view.View$PerformClick.run(View.java:22265)
        at android.os.Handler.handleCallback(Handler.java:751)
        at android.os.Handler.dispatchMessage(Handler.java:95)
        at android.os.Looper.loop(Looper.java:154)
        at android.app.ActivityThread.main(ActivityThread.java:6077)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)

You need to keep references of the root view in order to call `findViewById()` to find the child view of that root view. You added the `EditText` in the DialogView but tried to retrieve it from root view of `MainMenu` Activity which is not possible. Better, create another custom dialog which would have `EditText` already for password. — cgb_pandey, Jun 13 '20 at 04:07

score 0 · Answer 1 · edited Jun 12 '20 at 18:20

0

You can pass that View using intent or you can make that view to constant to change the view value on other activity or class

edited Jun 12 '20 at 18:20

answered Jun 12 '20 at 09:22

Jignesh Mayani

6,937
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I read that you cannot pass a view in intent here : https://stackoverflow.com/questions/40485206/passing-view-with-intent How should I do? – Jos B Jun 12 '20 at 10:24
then you can Store view in Constant file or Application extended file – Jignesh Mayani Jun 12 '20 at 10:40

How to get a view id created programmatically in another class?

1 Answers1