DoctorHome.java

package com.example.loginpage;

import androidx.appcompat.app.AppCompatActivity;
import androidx.cardview.widget.CardView;

import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.view.View;
import android.widget.Toast;

public class DoctorHome extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_doctor_home);

        SharedPreferences sharedPreferences1 = getSharedPreferences("shared_prefs", Context.MODE_PRIVATE);
        String username = sharedPreferences1.getString("username","").toString();
        Toast.makeText(getApplicationContext(), "Welcome Doctor "+username, Toast.LENGTH_SHORT).show();

        CardView exit = findViewById(R.id.cardExit);
        exit.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                SharedPreferences.Editor editor = sharedPreferences1.edit();
                editor.clear();
                editor.apply();
                startActivity(new Intent(DoctorHome.this,DoctorLogin.class));
            }
        });
    }
}