How to store metadata in buttons in android?

Question

In my android app, when I create a button with java code, I want to be able to store a string inside it, and then later when it is pressed, get that string again.

Can anyone show me how to do this?

Thanks,

Answer 1

You can use View.setTag() and View.getTag() to store and retrive String. So when your button pressed, you probably have a callback to OnClickListener, with method onClick(View v), so you can retrive your String there using v.getTag().

Answer 2

Start by creating the button in the xml file (assuming activity_main.xml)

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools" 
    android:layout_width="match_parent"
    android:layout_height="match_parent" 
    tools:context=".MainActivity">

        <Button
            android:id="@+id/btnMessage"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:onClick="onClick"
            android:text="Click" />

</LinearLayout>

Then from your own activity you can find it and add/retrieve information from it.

public class MainActivity extends ActionBarActivity {

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

        // find button by id
        Button btn = (Button)findViewById(R.id.btnMessage);

        // enclose secret message
        btn.setTag("Bruce Wayne is Batman");
    }
    
    // this function is triggered when the button is pressed
    public void onClick(View view) {

        // retrieve secret message
        String message = (String) view.getTag();

        // display message in the console
        Log.d("Tag", message);
    }
}    

This method is useful to hide information (such as database keys or superheroes' secret identities).