Signup.java

package change.com.animationwithsplash;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;

import android.app.ProgressDialog;
import android.content.Intent;
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.OnFailureListener;
import com.google.android.gms.tasks.Task;
import com.google.firebase.auth.AuthResult;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.auth.FirebaseUser;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;

import java.util.HashMap;

public class Signup extends AppCompatActivity {
    TextView login ;
    EditText Username,Email,Password;
    Button btn_register;
    FirebaseAuth auth;
    DatabaseReference reference;
    ProgressDialog pd;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_signup);
        login = findViewById(R.id.logintext);

        Username = findViewById(R.id.username);
        Email = findViewById(R.id.email);
        Password = findViewById(R.id.password);
        btn_register = findViewById(R.id.register);
        auth = FirebaseAuth.getInstance();

        pd = new ProgressDialog(this);

        btn_register.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String txt_username = Username.getText().toString();
                String txt_email = Email.getText().toString();
                String txt_password = Password.getText().toString();
                if(TextUtils.isEmpty(txt_username)||TextUtils.isEmpty(txt_email)||TextUtils.isEmpty(txt_password))
                {
                    Toast.makeText(Signup.this,"Fields cannot be empty",Toast.LENGTH_SHORT).show();
                }
                else if(txt_password.length()< 6)
                {
                    Toast.makeText(Signup.this,"Too short password",Toast.LENGTH_SHORT).show();
                }
                else
                {
                    register(txt_username,txt_email,txt_password);
                }
            }
        });

        login.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent(Signup.this,Login.class);
                startActivity(intent);
            }
        });
    }
    private void register(final String username, String email, String password){
        pd.setMessage("Please Wait");
        pd.show();
        auth.createUserWithEmailAndPassword(email,password)
                .addOnCompleteListener(new OnCompleteListener<AuthResult>() {
                    @Override
                    public void onComplete(@NonNull Task<AuthResult> task) {
                        if(task.isSuccessful())
                        {
                            FirebaseUser firebaseUser = auth.getCurrentUser();
                            assert firebaseUser != null;
                            String userId = firebaseUser.getUid();
                            reference = FirebaseDatabase.getInstance().getReference("Users").child(userId);
                            HashMap<String,String> hashMap = new HashMap<>();
                            hashMap.put("id",userId);
                            hashMap.put("Username",username);
                            reference.setValue(hashMap).addOnCompleteListener(new OnCompleteListener<Void>() {
                                @Override
                                public void onComplete(@NonNull Task<Void> task) {
                                    if(task.isSuccessful())
                                    {
                                        Intent intent = new Intent(Signup.this,HomePage.class);
                                        intent.addFlags(intent.FLAG_ACTIVITY_CLEAR_TASK|intent.FLAG_ACTIVITY_NEW_TASK);
                                        startActivity(intent);
                                        finish();
                                    }
                                }
                            });
                        }else {
                            Toast.makeText(Signup.this,"You cannot register with this email or password",Toast.LENGTH_SHORT).show();
                        }
                    }
                }).addOnFailureListener(new OnFailureListener() {
            @Override
            public void onFailure(@NonNull Exception e) {
                pd.dismiss();
                Toast.makeText(Signup.this, e.getMessage(), Toast.LENGTH_SHORT).show();
            }
        });
    }
}