CODEWITHSUNDEEP
androidnull
Shamsul Arefin
Shamsul Arefin

Reputation: 1917

getSupportActionBar() is returning null when calling setDisplayHomeAsUpEnabled()

I am facing a problem of getting null in getSupportActionBar(), when setting toolbar as actionbar in an activity and setting the back button programmatically from supportActionBar, the exception I get is,

Attempt to invoke virtual method 'void android.app.ActionBar' on a null object reference

here is the xml view of the activity, the toolbar is included from another layout

<RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">
        <include layout="@layout/toolbar_ftp"
            android:id="@+id/include" />
        <fragment
            xmlns:android="http://schemas.android.com/apk/res/android"
            android:id="@+id/mapView"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:name="com.google.android.gms.maps.SupportMapFragment"
            android:layout_below="@+id/include"
            android:layout_alignParentStart="true" />
        <RelativeLayout
            android:layout_alignParentBottom="true"
            android:id="@+id/below_layout"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:paddingBottom="16dp"
            android:background="@color/white">
            <TextView
                android:layout_below="@+id/line11"
                android:id="@+id/txt_search_date"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:textSize="18sp"
                android:layout_margin="16dp"
                android:text="@string/search_by_Date"/>
            <RelativeLayout
                android:id="@+id/rl_cal_pick"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_below="@+id/txt_search_date"
                >
                <ImageView
                    android:id="@+id/icon_secheudel"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_alignTop="@+id/rlBoxtime"
                    android:layout_alignBottom="@+id/rlBoxtime"

                    android:src="@mipmap/ic_clock_red"
                    android:tint="@color/colorPrimary"/>
                <RelativeLayout
                    android:id="@+id/rlBoxtime"
                    android:layout_toRightOf="@+id/icon_secheudel"
                    android:background="@drawable/blue_out_line"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:paddingLeft="5dp"
                    android:paddingRight="3dp"
                    android:paddingTop="3.5dp"
                    android:paddingBottom="3.5dp"
                    android:layout_marginLeft="0dp">
                    <TextView
                        android:id="@+id/txt_chosen_date"
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:layout_marginRight="5dp"
                        android:minWidth="30dp"
                        android:text=""/>
                    <ImageView
                        android:layout_width="20dp"
                        android:layout_height="20dp"
                        android:layout_toRightOf="@+id/txt_chosen_date"
                        android:layout_centerVertical="true"
                        android:src="@mipmap/ic_calendar_schedule"
                        android:tint="@color/colorAccent"
                        android:layout_marginRight="2.5dp"/>

                </RelativeLayout>

            </RelativeLayout>

            <TextView
                android:id="@+id/btn_tommorow"
                android:text="@string/tommorow"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:textAllCaps="false"
                android:gravity="center"
                android:layout_alignTop="@+id/rl_cal_pick"
                android:layout_alignBottom="@+id/rl_cal_pick"
                android:layout_toRightOf="@+id/tvTOday"
                android:textColor="@color/colorAccent"
                android:padding="5dp"
                android:background="@drawable/blue_out_line"
                style="@style/borderless_blue_text_button"
                />

            <TextView
                android:id="@+id/tvTOday"
                android:text="@string/today"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:textAllCaps="false"
                android:gravity="center"
                android:padding="5dp"

                android:layout_marginLeft="10dp"
                android:layout_alignTop="@+id/rl_cal_pick"
                android:layout_alignBottom="@+id/rl_cal_pick"
                android:layout_toRightOf="@+id/rl_cal_pick"
                android:textColor="@color/colorAccent"
                android:background="@drawable/blue_out_line"
                android:layout_marginRight="8dp"/>
        </RelativeLayout>
    </RelativeLayout>

Here is the toolbar_ftp.xml file

<android.support.v7.widget.Toolbar xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/toolbar"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:background="@color/white"
    android:fitsSystemWindows="true"
    android:minHeight="?attr/actionBarSize"
    app:theme="@style/ThemeOverlay.AppCompat.Light">
    <ImageView
        android:layout_width="200dp"
        android:layout_height="40dp"

        android:layout_gravity="center"
        android:scaleType="centerInside"
        android:src="@drawable/ftp_home_logo"
        tools:ignore="ContentDescription" />
</android.support.v7.widget.Toolbar>

Here is the toolbar code 

Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
        getSupportActionBar().setDisplayShowHomeEnabled(true);
        getSupportActionBar().setDisplayShowTitleEnabled(false);

Upvotes: 2

Views: 1111

Answers (5)

Ashile The Great
Ashile The Great

Reputation: 131

this may be silly but error also happens when setContentView line accidentally removed!

 @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

       setContentView(R.layout.activity_home);
}

Upvotes: 0

Shamsul Arefin
Shamsul Arefin

Reputation: 1917

I tried all the solutions posted here, Still, I was experiencing the crash. Later I figured out the problem, It was because of giving an additional id in the include statement of the xml view. 

 <include layout="@layout/toolbar_ftp"
                android:id="@+id/include" />

When referencing the toolbar, it became ambiguous for id inside id.

Upvotes: 2

Bapusaheb Shinde
Bapusaheb Shinde

Reputation: 849

if you are using AppcompatActivity try this :

this.getSupportActionBar().setDisplayHomeAsUpEnabled(true);

if you are using ActionBarActivity then try this :

this.getActionBar().setDisplayHomeAsUpEnabled(true);

Upvotes: 0

user8626261
user8626261

Reputation:

hi try to change theme style of your app

 <!-- Base application theme. -->
    <style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
        <!-- Customize your theme here. -->
        <item name="colorPrimary">@color/colorPrimary</item>
        <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
        <item name="colorAccent">@color/colorPrimary</item>

        <item name="android:textColor">@color/black</item>
        <item name="android:actionOverflowButtonStyle">@style/ActionButtonOverflow</item>
    </style>

Upvotes: 2

Ankita
Ankita

Reputation: 1159

In most of the cases this problem can be caused by your theme. Check it again, and make sure that it's parent with Theme.AppCompat.Light.DarkActionBar.

<style name="MyTheme" parent="Theme.AppCompat.Light.DarkActionBar">
    <item name="android:windowNoTitle">true</item>
    <item name="windowActionBar">true</item>
    ...
</style>

If your activity extends AppCompatActivity or ActionBarActivity, then you must call getSupportActionBar().

Upvotes: 0

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