App crashes on clicking on textView in fragment - android-fragments

Question

I'm creating an app in which there are three tab activity.In tab Three i have a textview name as login text whenever user click on this text a new activity should be opened but app crashes when we click on this.
I have done many research to resolve this problem but i'm unable to resolve at last i'm here for the solution of my problem Please help.
Thanks in advance.
This is my loginActivity.
import android.app.ProgressDialog;
import android.content.Intent;
import android.support.annotation.NonNull;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.text.TextUtils;
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.AuthResult;
import com.google.firebase.auth.FirebaseAuth;
public class loginActivity extends AppCompatActivity implements View.OnClickListener {
private EditText email_Id;
private EditText password;
private TextView sign_Up;
private Button sign_In;
private ProgressDialog progressDialog;
private FirebaseAuth firebaseAuth;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login);
firebaseAuth=FirebaseAuth.getInstance();
// if(firebaseAuth.getCurrentUser()!=null){
// directly start user profile activity
// finish();
// startActivity(new Intent(this,userProfileActivity.class));
//}
progressDialog=new ProgressDialog(this);
email_Id=(EditText)findViewById(R.id.email_id);
password=(EditText)findViewById(R.id.password);
sign_In=(Button)findViewById(R.id.sign_In);
sign_Up=(TextView)findViewById(R.id.sign_up);
sign_In.setOnClickListener(this);
sign_Up.setOnClickListener(this);
}
private void user_Login(){
String email=email_Id.getText().toString().trim();
String pass_word=password.getText().toString().trim();
if(TextUtils.isEmpty(email)){
// email is empty
Toast.makeText(this,"please enter email",Toast.LENGTH_SHORT).show();
return;// to stop the function from executation.
}
if(TextUtils.isEmpty(pass_word)){
// email is empty
Toast.makeText(this,"please enter password",Toast.LENGTH_SHORT).show();
return;
}
// here if everything ok the user will be register
progressDialog.setMessage("Registering User,please wait...");
progressDialog.show();
firebaseAuth.signInWithEmailAndPassword(email,pass_word)
.addOnCompleteListener(this, new OnCompleteListener<AuthResult>() {
#Override
public void onComplete(#NonNull Task<AuthResult> task) {
progressDialog.dismiss();
if (task.isSuccessful()){
// start user profile activity
finish();
startActivity(new Intent(getApplicationContext(),userProfileActivity.class));
}
}
});
}
#Override
public void onClick(View view) {
if (view==sign_In){
// start user profile activity
user_Login();
}
if(view==sign_Up){
// go to registeration page
finish();
startActivity(new Intent(this,FragmentThree.class));
}
}
}
this is declaration
This is my login method

Answer 1

The following line in your code throws the exception:
sign_Up.setOnClickListener(this);
The problem is, that sign_Up is null!
You set sign_Up with: sign_Up=(TextView)findViewById(R.id.sign_up);
Make sure, that setContentView(R.layout.activity_login); (activity_login) is the right one. If, try to clean and rebuild your project and try again.
Update: It is possible, that sign_up should be a button? If, you make a wrong cast!
Change the TextView in this line:
sign_Up=(TextView)findViewById(R.id.sign_up);
to Button, like this:
sign_Up=(Button)findViewById(R.id.sign_up);