What can I do to fix a null pointer error in Android for toolbar?

Question

Even after I had ensured that the toolbar id is well linked in the main activity where I declared the Toolbar, it still does push an error.

I am trying to create and understand a navigation drawer in android studio. I have once done this navigation and it worked, just trying to build a project using navigation and it started showing this error.

Here are my codes:

This is the main activity:

package com.example.demoapp;

import androidx.appcompat.app.ActionBarDrawerToggle;
import androidx.appcompat.app.AppCompatActivity;
import androidx.appcompat.widget.Toolbar;
import androidx.drawerlayout.widget.DrawerLayout;

import android.os.Bundle;

public class MainActivity extends AppCompatActivity {

    Toolbar toolbar;
    DrawerLayout drawerLayout;
    ActionBarDrawerToggle actionBarDrawerToggle;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        toolbar.findViewById(R.id.tool_bar);
        setSupportActionBar(toolbar);
    }
}

This is the toolbar layout.xml for the tool bar:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent">

    <androidx.appcompat.widget.Toolbar
        android:layout_width="match_parent"
        android:layout_height="?attr/actionBarSize"
        android:background="@color/colorPrimaryDark"
        android:id="@+id/tool_bar"
        android:theme="@style/ThemeOverlay.AppCompat.Dark"
        />

</LinearLayout>

This is the main activity xml where I included all the fragments of xml i needed to make the navigation view work

<?xml version="1.0" encoding="utf-8"?>
<androidx.drawerlayout.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:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/drawer"
    tools:context=".MainActivity">

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

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

    <com.google.android.material.navigation.NavigationView
        android:layout_width="300dp"
        android:layout_height="match_parent"
        android:id="@+id/navigationView"
        app:menu="@menu/drawer_menu"
        app:headerLayout="@layout/drawer_header"
        android:fitsSystemWindows="true"
        android:layout_gravity="start"
        />



</androidx.drawerlayout.widget.DrawerLayout>

In the error log, you can see which line of your code is throwing null pointer exception. It can help you figure out the issue. — ProgrammingEnthusiast, Nov 27 '20 at 23:44
Does this answer your question? [What is a NullPointerException, and how do I fix it?](https://stackoverflow.com/questions/218384/what-is-a-nullpointerexception-and-how-do-i-fix-it) — Selvin, Nov 27 '20 at 23:45

score 2 · Answer 1 · answered Nov 27 '20 at 23:48

2

As @Selvin mentioned in the comment section, replace this line:

toolbar.findViewById(R.id.tool_bar);

with the following line:

toolbar = findViewById(R.id.tool_bar);

answered Nov 27 '20 at 23:48

ProgrammingEnthusiast

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What can I do to fix a null pointer error in Android for toolbar?

1 Answers1