Question

I am developing an Android app with multiple Activities. In order to avoid writing the same menu and Intent listener code into each Activity, I decided to create one file and implement it on every Activity like the following:

public class MainActivity extends Activity implements CommonTools{ ...

My commonTools file which contains my menu code is as follows:

import android.view.Menu;

public interface CommonTools {

    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.activity_main, menu);
        menu.findItem(R.id.menu_home).setIntent(
            new Intent(this, MainActivity.class));
        menu.findItem(R.id.menu_articles).setIntent(
            new Intent(this, ArticlesActivity.class));
        return true;
    }
}

The problem is I get an “Abstract methods do not specify a body” error message.

I have not declared anything abstract and don’t understand what the issue is.

Answer 1

An Interface can’t contain any code. What you need to do is extend Activity then extend that class. E.g.

public class CommonTools extends Activity {

  public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.activity_main, menu);
    menu.findItem(R.id.menu_home).setIntent(
        new Intent(this, MainActivity.class));
    menu.findItem(R.id.menu_articles).setIntent(
        new Intent(this, ArticlesActivity.class));
    return true;
  }
}

Then define your activities:

public class MainActivity extends CommonTools {
 ....
}