getSupportActionBar() NullPointerException

Question

In onCreate() method of activity I have this code for ToolBar:

toolbar = (Toolbar) findViewById(R.id.tool_bar);
setSupportActionBar(toolbar);
getSupportActionBar().setDisplayHomeAsUpEnabled(true);

My IDE warms me that getSupportActionBar().setDisplayHomeAsUpEnabled(true); may produce NullPointerException.

My question is should I ignore it and how can I fix it anyway?

Answer 1

The IDE warns you about a potential NullPointerException because there are many cases where the app could throw one. For the example you could be using a NoActionBar theme for your whole Application (or just for the concerned activity), but still you're trying to retrieve a reference to the action bar using getActionBar() (or getSupportActionBar()).

Just ignore the warning, but keep in mind the notes above.

UPDATE:

You can get rid of the warning by explicitly checking for nullability:

toolbar = (Toolbar) findViewById(R.id.tool_bar);
if (toolbar != null) {
    // you can safely invoke methods on the Toolbar
    setSupportActionBar(toolbar);
    getSupportActionBar().setDisplayHomeAsUpEnabled(true);
} else {
    // Toolbar is null, handle it
}