android studio自定义toolbar

<style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">

第二步：

<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.Toolbar
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:minHeight="?android:attr/actionBarSize"
android:id="@+id/toolbar"
app:theme="@style/Base.ThemeOverlay.AppCompat.Dark.ActionBar"
android:background="@color/colorPrimaryDark"
>
<RelativeLayoutandroid:layout_width="match_parent"
android:layout_height="wrap_content">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="0 item selected"
android:id="@+id/counter_text"
android:textSize="18dp"
android:textColor="#ffffff"
android:textStyle="bold"
/>
</RelativeLayout>

</android.support.v7.widget.Toolbar>

<?xml version="1.0" encoding="utf-8"?>
<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"
android:orientation="vertical"
tools:context=".MainActivity"
>

<include
layout="@layout/tool_bar"/>

</LinearLayout>

第四步：

public class MainActivity extends AppCompatActivity {
Toolbar toolbar;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
toolbar=(Toolbar)findViewById(R.id.toolbar);
setSupportActionBar(toolbar);

}
}