In Android development, to use the ToolBar control to replace the ActionBar control, you need to use the setSupportActionBar() method in the java code, as follows:

1 Toolbar toolbar = (Toolbar) this.findViewById(R.id.toolBar);
2 this.setSupportActionBar(toolbar);

There are two common types of errors:

1. Method parameter error

This kind of error is because the wrong class is imported, put the following code

1 import android.widget.Toolbar;

Replace with the following code

1 import android.support.v7.widget.Toolbar;

2. Method name error

Need to inherit ActionBarActivity class or AppCompatActivity class.

Because the ActionBarActivity class is obsolete, it is recommended to inherit the AppCompatActivity class.

Note: If you inherit the AppCompatActivity class, you need to use the Theme.AppCompat.Light.NoActionBar theme, for example

<style name="AppTheme.Base" parent="Theme.AppCompat.Light.NoActionBar">
        <item name="android:windowNoTitle">true</item>
        <item name="android:windowActionBar">false</item>
</style>