无法在onOptionsItemSelected（MenuItem item）方法中解析Textview

Question

Here is MainActivity.java

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        TextView myTxt = findViewById(R.id.view);


       }



    public boolean onCreateOptionsMenu(Menu menu) {

        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.test, menu);
        return true;
    }

    public boolean onOptionsItemSelected(MenuItem item) {

        switch (item.getItemId()) {
            case R.id.toast:
                      myTxt.setText("what a yummy toast!");

                return true;
            case R.id.nutella:

                return true;

            case R.id.milk:


            default:
                return super.onOptionsItemSelected(item);// ken jét this .onOption infinite loop
        }

    }

}

Here is the menu XML file

<?xml version="1.0" encoding="utf-8"?>

<item android:title="@string/toast"
    android:id="@+id/toast"/>


<item android:title="@string/nutella"
    android:id="@+id/nutella"/>

<item android:title="@string/milk"
    android:id="@+id/milk"/>

I want to handle myTxt which is a textview whenever I choose an item from the menu option the problem is that myTxt is not recognized. How Should I handle Menus correctly and what are Here is an image for more explanation

Answer 1

You need to declare your TextView myTxt as global outside onCreate() method

SAMPLE CODE

public class MainActivity extends AppCompatActivity {

    TextView myTxt;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

         myTxt = findViewById(R.id.view);


       }



    public boolean onCreateOptionsMenu(Menu menu) {

        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.test, menu);
        return true;
    }

    public boolean onOptionsItemSelected(MenuItem item) {

        switch (item.getItemId()) {
            case R.id.toast:
                      myTxt.setText("what a yummy toast!");

                return true;
            case R.id.nutella:

                return true;

            case R.id.milk:


            default:
                return super.onOptionsItemSelected(item);// ken jét this .onOption infinite loop
        }

    }

}

Answer 2

myTxt is declared inside onCreate() so you can not access it from outside this function. Try declare it outside onCreate()

public class MainActivity extends AppCompatActivity {
private TextView myTxt;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    myTxt = findViewById(R.id.view);


   }



public boolean onCreateOptionsMenu(Menu menu) {

    MenuInflater inflater = getMenuInflater();
    inflater.inflate(R.menu.test, menu);
    return true;
}

public boolean onOptionsItemSelected(MenuItem item) {

    switch (item.getItemId()) {
        case R.id.toast:
                  myTxt.setText("what a yummy toast!");

            return true;
        case R.id.nutella:

            return true;

        case R.id.milk:


        default:
            return super.onOptionsItemSelected(item);// ken jét this .onOption infinite loop
    }

}

}