Why does findViewById return null?

Question

Why does my findViewById return null here swipeRefreshLayout = findViewById(R.id.swipeRefreshLayoutDashboard);?

I already tried using .getRootView() and going down the hierarchy by myself, but without any success. Can you maybe help me?

DashboardActivity.java

package eu.niehus.app;

import android.app.AlertDialog;
import android.app.DialogFragment;
import android.content.DialogInterface;
import android.content.Intent;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.NavigationView;
import android.support.v4.view.GravityCompat;
import android.support.v4.widget.DrawerLayout;
import android.support.v4.widget.SwipeRefreshLayout;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import com.github.mikephil.charting.charts.LineChart;
import com.github.mikephil.charting.components.YAxis;
import com.github.mikephil.charting.data.Entry;
import com.github.mikephil.charting.data.LineData;
import com.github.mikephil.charting.data.LineDataSet;
import com.github.mikephil.charting.utils.EntryXComparator;

import java.util.ArrayList;
import java.util.Calendar;
import java.util.Collections;
import java.util.List;
public class DashboardActivity extends AppCompatActivity
        implements NavigationView.OnNavigationItemSelectedListener {

    private SwipeRefreshLayout swipeRefreshLayout;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_dashboard);
        Toolbar toolbar = findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        FloatingActionButton fab = findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                DialogFragment fragment = new AddWeightDialog();
                fragment.show(getFragmentManager(), "fab");
            }
        });

        DrawerLayout drawer = findViewById(R.id.drawer_layout);
        ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
                this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
        drawer.addDrawerListener(toggle);
        toggle.syncState();

        NavigationView navigationView = findViewById(R.id.nav_view);
        navigationView.setNavigationItemSelectedListener(this);

        swipeRefreshLayout = findViewById(R.id.swipeRefreshLayoutDashboard);
        swipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
            @Override
            public void onRefresh() {
                Log.i("onRefreshListener", "refreshing");
                update();
            }
        });
    }
}

activity_dashboard.xml:

   <?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.DrawerLayout 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/drawer_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true"
    tools:openDrawer="start">

    <include
        layout="@layout/app_bar_dashboard"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

    <android.support.design.widget.NavigationView
        android:id="@+id/nav_view"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="start"
        android:fitsSystemWindows="true"
        app:headerLayout="@layout/nav_header_dashboard"
        app:menu="@menu/activity_dashboard_drawer" />

</android.support.v4.widget.DrawerLayout>

app_bar_dashboard.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout 
        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:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".DashboardActivity"
        android:id="@+id/constraintLayout">

    <android.support.design.widget.AppBarLayout
            android:layout_width="0dp"
            android:theme="@style/AppTheme.AppBarOverlay"
            android:id="@+id/appBarLayout"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            android:layout_height="wrap_content">

        <android.support.v7.widget.Toolbar
                android:id="@+id/toolbar"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:background="?attr/colorPrimary"
                app:popupTheme="@style/AppTheme.PopupOverlay"
                />

    </android.support.design.widget.AppBarLayout>

    <include
            layout="@layout/content_dashboard"
            android:layout_height="0dp"
            android:layout_width="0dp"
            android:id="@+id/include"
            app:layout_constraintTop_toBottomOf="@+id/appBarLayout"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            />

    <android.support.design.widget.FloatingActionButton
            android:id="@+id/fab"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            app:srcCompat="@android:drawable/ic_input_add"
            app:layout_constraintEnd_toEndOf="parent"
            android:layout_marginEnd="8dp"
            app:layout_constraintBottom_toBottomOf="parent"
            android:layout_marginBottom="8dp"/>

</android.support.constraint.ConstraintLayout>

content_dashboard.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.SwipeRefreshLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/swipeRefreshLayoutDashboard">

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

        <TableLayout
                android:layout_width="match_parent"
                android:layout_height="wrap_content">

            <TableRow
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:id="@+id/tableRowWeighGraph"
                    android:minHeight="200dp">

                <com.github.mikephil.charting.charts.LineChart
                        android:id="@+id/lineChart"
                        android:layout_width="match_parent"
                        android:layout_height="match_parent"
                        android:layout_weight="999"/>
            </TableRow>

        </TableLayout>
    </ScrollView>

</android.support.v4.widget.SwipeRefreshLayout>

can you share your imports in activity because i guess you are using wrong R.layout instead of your apps. — vikas kumar, Apr 19 '18 at 18:54
Possible duplicate of [findViewById not working for an include?](https://stackoverflow.com/questions/10803672/findviewbyid-not-working-for-an-include) — pushasha, Apr 19 '18 at 18:54
According to the duplicated flag another user has set, this should be solved by removing the id on the include @SvenNiehus — cutiko, Apr 19 '18 at 19:06
the above comment may work, removing the id paramter from include tag — vikas kumar, Apr 19 '18 at 19:09
I've solved it with adding an android:id parameter on my 'include' inside app_bar_dashboard.xml and using this to get my SwipeRefreshLayout. — Sven Niehus, Apr 19 '18 at 19:11

score 0 · Answer 1 · answered Apr 19 '18 at 19:02

0

If you include layout in another layout, First you need to create object for that included layout with its Id using findViewById. Then call findViewById on it for swipe to refresh layout.

answered Apr 19 '18 at 19:02

TRK P

366
2
9

score 0 · Answer 2 · answered Apr 19 '18 at 19:20

I've solved it with adding an android:id parameter on my 'include' inside app_bar_dashboard.xml and using this to get my SwipeRefreshLayout.

Here is the updated source code:

DashboardActivity.java:

package eu.niehus.app;

import android.app.AlertDialog;
import android.app.DialogFragment;
import android.content.DialogInterface;
import android.content.Intent;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.constraint.ConstraintLayout;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.NavigationView;
import android.support.v4.view.GravityCompat;
import android.support.v4.widget.DrawerLayout;
import android.support.v4.widget.SwipeRefreshLayout;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import com.github.mikephil.charting.charts.LineChart;
import com.github.mikephil.charting.components.YAxis;
import com.github.mikephil.charting.data.Entry;
import com.github.mikephil.charting.data.LineData;
import com.github.mikephil.charting.data.LineDataSet;
import com.github.mikephil.charting.utils.EntryXComparator;
import eu.niehus.app.common.DBHelper;

import java.util.ArrayList;
import java.util.Calendar;
import java.util.Collections;
import java.util.List;

public class DashboardActivity extends AppCompatActivity
        implements NavigationView.OnNavigationItemSelectedListener {

    private ConstraintLayout outer;
    private SwipeRefreshLayout swipeRefreshLayout;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_dashboard);
        Toolbar toolbar = findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        FloatingActionButton fab = findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                DialogFragment fragment = new AddWeightDialog();
                fragment.show(getFragmentManager(), "fab");
            }
        });

        DrawerLayout drawer = findViewById(R.id.drawer_layout);
        ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
                this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
        drawer.addDrawerListener(toggle);
        toggle.syncState();

        NavigationView navigationView = findViewById(R.id.nav_view);
        navigationView.setNavigationItemSelectedListener(this);

        dbHelper = new DBHelper(this);
        outer = findViewById(R.id.outer);
        swipeRefreshLayout = outer.findViewById(R.id.swipeRefreshLayoutInclude);
        swipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
            @Override
            public void onRefresh() {
                Log.i("onRefreshListener", "refreshing");
                update();
            }
        });
        lineChart = swipeRefreshLayout.findViewById(R.id.lineChartWeight);
        lineChart.setTouchEnabled(false);
        update();
    }
}

activity_dashboard.xml:

<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.DrawerLayout 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/drawer_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true"
    tools:openDrawer="start">

    <include
        android:id="@+id/outer"
        layout="@layout/app_bar_dashboard"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

    <android.support.design.widget.NavigationView
        android:id="@+id/nav_view"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="start"
        android:fitsSystemWindows="true"
        app:headerLayout="@layout/nav_header_dashboard"
        app:menu="@menu/activity_dashboard_drawer" />

</android.support.v4.widget.DrawerLayout>

app_bar_dashboard.xml:

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
        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:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".DashboardActivity"
        android:id="@+id/constraintLayout">

    <android.support.design.widget.AppBarLayout
            android:layout_width="0dp"
            android:theme="@style/AppTheme.AppBarOverlay"
            android:id="@+id/appBarLayout"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            android:layout_height="wrap_content">

        <android.support.v7.widget.Toolbar
                android:id="@+id/toolbar"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:background="?attr/colorPrimary"
                app:popupTheme="@style/AppTheme.PopupOverlay"
                />

    </android.support.design.widget.AppBarLayout>

    <include
            layout="@layout/content_dashboard"
            android:layout_height="0dp"
            android:layout_width="0dp"
            android:id="@+id/swipeRefreshLayoutInclude"
            app:layout_constraintTop_toBottomOf="@+id/appBarLayout"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            />

    <android.support.design.widget.FloatingActionButton
            android:id="@+id/fab"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            app:srcCompat="@android:drawable/ic_input_add"
            app:layout_constraintEnd_toEndOf="parent"
            android:layout_marginEnd="8dp"
            app:layout_constraintBottom_toBottomOf="parent"
            android:layout_marginBottom="8dp"/>

</android.support.constraint.ConstraintLayout>

content_dashboard.xml:

<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.SwipeRefreshLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/swipeRefreshLayoutDashboard">

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

        <TableLayout
                android:layout_width="match_parent"
                android:layout_height="wrap_content">

            <TableRow
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:id="@+id/tableRowWeighGraph"
                    android:minHeight="200dp">

                <com.github.mikephil.charting.charts.LineChart
                        android:id="@+id/lineChartWeight"
                        android:layout_width="match_parent"
                        android:layout_height="match_parent"
                        android:layout_weight="999"/>
            </TableRow>

        </TableLayout>
    </ScrollView>

</android.support.v4.widget.SwipeRefreshLayout>

score 0 · Answer 3 · answered Apr 20 '18 at 03:03

0

Try make a cast: swipeRefreshLayout = (SwipeRefreshLayout) findViewById(R.id.swipeRefreshLayoutDashboard);

answered Apr 20 '18 at 03:03

Augusto

3,825
9
45
93

Why does findViewById return null?

3 Answers3