Add Icon to the left of the title in the action bar in android

You can do the following:

1- create your file_name.xml then Add Toolbar.

2- add RelativeLayout inside the Toolbar's tag.

3- add your views i.e.(ImageButton,TextView,...)

Note: The TextView you are adding is the title of Toolbar.

Sample Code: file_name.xml

<android.support.v7.widget.Toolbar
        android:id="@+id/products_toolbar"
        android:layout_width="match_parent"
        android:layout_height="?attr/actionBarSize"
        android:background="@color/colorPrimaryDark"
        app:layout_collapseMode="pin"
        app:titleTextColor="@android:color/white">

        <RelativeLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent">

            <TextView
                android:id="@+id/toolbar_title"
                android:layout_width="wrap_content"
                android:layout_height="match_parent"
                android:text="Title"
                android:gravity="center"
                android:textColor="@android:color/white"
                android:textSize="20dp"
                android:textStyle="bold"
                android:layout_alignParentStart="true"/>

            <ImageButton
                android:id="@+id/toolbar_button"
                android:layout_width="wrap_content"
                android:layout_height="match_parent"
                android:src="@drawable/ic_icon_24dp"
                style="@style/Widget.AppCompat.Button.Borderless"
                android:layout_alignParentEnd="true"/>

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

Output:

Recommended way

getSupportActionBar().setHomeAsUpIndicator(R.drawable.ic_settings_24dp);// set drawable icon
getSupportActionBar().setDisplayHomeAsUpEnabled(true);

Handle icon click event

@Override
public boolean onOptionsItemSelected(MenuItem item) {

    switch (item.getItemId()) {
        case android.R.id.home:
            Toast.makeText(this, "click..!!", Toast.LENGTH_SHORT).show();
            return true;
        default:
            return super.onOptionsItemSelected(item);

    }
}