MainActivity.java sp

package com.example.saigopinarimeti.helloworld;

import android.content.Intent;
import android.content.SharedPreferences;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

    EditText editText;
    Button login;

    SharedPreferences sharedPreferences;
    SharedPreferences.Editor editor;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        editText = findViewById(R.id.username);
        login = findViewById(R.id.login);

        sharedPreferences = getSharedPreferences("user",MODE_PRIVATE);
        editor = sharedPreferences.edit();


        if (sharedPreferences.getBoolean("isLoggedIn",false)){
            startActivity(new Intent(this,HomeActivity.class));
            Toast.makeText(this, "already logged in", Toast.LENGTH_SHORT).show();
        }else{
            Toast.makeText(this, "please loggin", Toast.LENGTH_SHORT).show();
        }


        login.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                editor.putString("username",editText.getText().toString()).apply();
                editor.putBoolean("isLoggedIn",true).apply();
            }
        });




    }

}