MainActivity.java

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

        btn_save = findViewById(R.id.btn_save);
        btn_load = findViewById(R.id.btn_load);
        btn_second = findViewById(R.id.btn_second);
        ed_name = findViewById(R.id.ed1);
        ed_email = findViewById(R.id.ed2);

        //implementing onclick listener
        btn_save.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                //getdata from edittext and store in corresponding string file
                str_email = ed_email.getText().toString();
                str_name = ed_name.getText().toString();
                SharedPreferences sharedPreferences = getPreferences(Context.MODE_PRIVATE);
                //we need editor to edit created shared preference file
                SharedPreferences.Editor editor = sharedPreferences.edit();
                editor.putString("name",str_name);
                editor.putString("email",str_email);
                editor.apply();
            }
        });
    }