Android Facebook login with custom Login button

FbLoginWithCustomButtonOnAndroid.txt

build.gradle (Module: app)
==========================

// 1. 

buildscript {
    repositories {
        mavenCentral()
    }
}

// 2.

dependencies {
    compile 'com.facebook.android:facebook-android-sdk:4.18.0'
}



AndroidManifest.xml
===================

Put this inside 'application' tag inside AndroidManifest XML file.

<!-- 1. -->

        <meta-data android:name="com.facebook.sdk.ApplicationId"
            android:value="@string/facebook_app_id"/>
        <activity android:name="com.facebook.FacebookActivity"
            android:configChanges=
                "keyboard|keyboardHidden|screenLayout|screenSize|orientation"
            android:label="@string/app_name" />
        <activity
            android:name="com.facebook.CustomTabActivity"
            android:exported="true">
            <intent-filter>
                <action android:name="android.intent.action.VIEW" />
                <category android:name="android.intent.category.DEFAULT" />
                <category android:name="android.intent.category.BROWSABLE" />
                <data android:scheme="@string/fb_login_protocol_scheme" />
            </intent-filter>
        </activity>
        
        
VERY VERY IMPORTANT TO NOTE 
---------------------------

If you put the ids like this - android:value="525175644501670"
It crashes. Don't know why. 
You should put it like this - android:value="@string/facebook_app_id"



activity_main.xml
=================

<!-- 1. -->

<TextView
android:id="@+id/fb_login"
android:background="#FFFFFF"
android:layout_marginRight="30dp"
android:layout_marginLeft="30dp"
android:text="Login with Facebook"
android:gravity="center"
android:layout_width="match_parent"
android:layout_height="50dp" />



App.java
========
// This is the Application Context class.

// Put this inside onCreate of the Application Context class.
// Its important. Because Facebook SDK should be initialized before it is used

// 1. 
FacebookSdk.sdkInitialize(getApplicationContext());



MainActivity.java
=================

// 1.
// Put this outside onCreate of Activity or outside onCreateView of Fragment.

    TextView click;
    CallbackManager callbackManager;

// 2.
// If you are using FB login in a Fragment, this should be inside the parent Activity of the Fragment

@Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        callbackManager.onActivityResult(requestCode, resultCode, data);
    }
    
// 3.

callbackManager = CallbackManager.Factory.create();

        click = (TextView)findViewById(R.id.click);
        click.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                LoginManager.getInstance().logInWithReadPermissions(MainActivity.this, Arrays.asList("public_profile"));

            }
        });

LoginManager.getInstance().registerCallback(callbackManager,
                new FacebookCallback<LoginResult>() {
                    @Override
                    public void onSuccess(LoginResult loginResult) {
                        // App code
                    }

                    @Override
                    public void onCancel() {
                        // App code
                    }

                    @Override
                    public void onError(FacebookException exception) {
                        // App code
                    }
                });