I am getting stuck at this error. I am not getting where it goes wrong so I have gone through Logcat and there I saw this Fatal Exception. How to fix this error? I know here on the forum are a lot of pages describing solution for my problem.
I had read many forums fixing this exception but I didn't got the solution which will fixied this error.
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.easylearn, PID: 11793
java.lang.RuntimeException: Unable to instantiate activity
ComponentInfo{com.example.easylearn/com.example.easylearn.MainActivity}:
java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.Context
android.content.Context.getApplicationContext()' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2327)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method
'android.content.Context android.content.Context.getApplicationContext()' on a null object
reference
at android.content.ContextWrapper.getApplicationContext(ContextWrapper.java:107)
at com.example.easylearn.MainActivity.<init>(MainActivity.java:21)
at java.lang.Class.newInstance(Native Method)
at android.app.Instrumentation.newActivity(Instrumentation.java:1067)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2317)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616
This is my AndroidManifest.xml.
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.easylearn">
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity android:name=".HomeActivity"></activity>
<activity android:name=".LoginActivity" />
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
This is my MainActivity.java
package com.example.easylearn;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import android.content.Intent;
import android.media.MediaPlayer;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.Task;
import com.google.firebase.auth.FirebaseAuth;
public class MainActivity extends AppCompatActivity {
AppCompatActivity appCompatActivity = new LoginActivity(getApplicationContext());
EditText emailId,password;
Button btnSignUp;
TextView tvSignIn;
FirebaseAuth mFirebaseAuth;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mFirebaseAuth = FirebaseAuth.getInstance();
emailId = findViewById(R.id.editText);
password = findViewById(R.id.editText2);
btnSignUp = findViewById(R.id.button2);
tvSignIn = findViewById(R.id.textView);
btnSignUp.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String email = emailId.getText().toString();
String pwd = password.getText().toString();
if(email.isEmpty())
{
emailId.setError("Please enter email id");
emailId.requestFocus();
}
else if(pwd.isEmpty())
{
password.setError("Please enter password");
password.requestFocus();
}
else if(email.isEmpty() && pwd.isEmpty())
{
Toast.makeText(MainActivity.this,"Fiels are Empty!",Toast.LENGTH_SHORT).show();
}
else if(!(email.isEmpty() && pwd.isEmpty()))
{
mFirebaseAuth.createUserWithEmailAndPassword(email,pwd).addOnCompleteListener(MainActivity.this,
new OnCompleteListener<com.google.firebase.auth.AuthResult>() {
@Override
public void onComplete(@NonNull Task<com.google.firebase.auth.AuthResult> task)
{
if(task.isSuccessful())
{
Toast.makeText(MainActivity.this,"SignUp Unsuccessful,Please Try
Again..",Toast.LENGTH_SHORT).show();
}
else {
startActivity(new Intent(MainActivity.this,HomeActivity.class));
}
}
});
}
else
{
Toast.makeText(MainActivity.this,"Error Occured!",Toast.LENGTH_SHORT).show();
}
}
});
tvSignIn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent i = new Intent(MainActivity.this,LoginActivity.class);
startActivity(i);
}
});
}
}
This is my LoginActivity.java
package com.example.easylearn;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
import com.google.firebase.auth.FirebaseUser;
import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.Task;
import com.google.firebase.auth.FirebaseAuth;
public class LoginActivity extends AppCompatActivity {
private Context ctx;
public LoginActivity(Context ctx){
this.ctx = ctx;
}
EditText emailId,password;
Button btnSignIn;
TextView tvSignUp;
FirebaseAuth mFirebaseAuth;
private FirebaseAuth.AuthStateListener mAuthStateListener;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login);
mFirebaseAuth = FirebaseAuth.getInstance();
emailId = findViewById(R.id.editText);
password = findViewById(R.id.editText2);
btnSignIn = findViewById(R.id.button2);
tvSignUp = findViewById(R.id.textView);
mAuthStateListener = new FirebaseAuth.AuthStateListener() {
@Override
public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {
FirebaseUser mFirebaseUser = mFirebaseAuth.getCurrentUser();
if(mFirebaseUser != null){
Toast.makeText(LoginActivity.this,"You are logged in",Toast.LENGTH_SHORT).show();
Intent i = new Intent(LoginActivity.this,HomeActivity.class);
startActivity(i);
}
else{
Toast.makeText(LoginActivity.this,"Please login",Toast.LENGTH_SHORT).show();
}
}
};
btnSignIn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String email = emailId.getText().toString();
String pwd = password.getText().toString();
if(email.isEmpty())
{
emailId.setError("Please enter email id");
emailId.requestFocus();
}
else if(pwd.isEmpty())
{
password.setError("Please enter password");
password.requestFocus();
}
else if(email.isEmpty() && pwd.isEmpty())
{
Toast.makeText(LoginActivity.this,"Fiels are Empty!",Toast.LENGTH_SHORT).show();
}
else if(!(email.isEmpty() && pwd.isEmpty()))
{
mFirebaseAuth.signInWithEmailAndPassword(email,pwd).addOnCompleteListener(LoginActivity.this, new
OnCompleteListener<com.google.firebase.auth.AuthResult>() {
@Override
public void onComplete(@NonNull Task<com.google.firebase.auth.AuthResult> task)
{
if(!task.isSuccessful()){
Toast.makeText(ctx,"Login Error,Please Login
again..",Toast.LENGTH_SHORT).show();
}
else{
Intent inToHome = new Intent(LoginActivity.this,HomeActivity.class);
startActivity(inToHome);
}
}
});
}
else
{
Toast.makeText(ctx,"Error Occured!",Toast.LENGTH_SHORT).show();
}
}
});
tvSignUp.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intSignUp = new Intent(LoginActivity.this,MainActivity.class);
startActivity(intSignUp);
}
});
}
@Override
protected void onStart() {
super.onStart();
mFirebaseAuth.addAuthStateListener(mAuthStateListener);
}
}`
