MainActivity

import android.content.Intent;
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 {

    Button logInButton;
    Button regButton;
    EditText username;
    EditText password;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        username = (EditText) findViewById(R.id.username);
        password = (EditText) findViewById(R.id.password);


        logInButton = (Button) findViewById(R.id.login);
        logInButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                UserMenager um = UserMenager.getInstance();
                String user = username.getText().toString();
                String pass = password.getText().toString();

                if (um.validateUser(user, pass)) {
                    Toast.makeText(MainActivity.this, "hi" + user, Toast.LENGTH_SHORT).show();
                } else {
                    password.setText("");
                    password.setError("invalid pass");
                }


            }
        });

        regButton = (Button) findViewById(R.id.register);

        regButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent(MainActivity.this, RegActivity.class);
                startActivity(intent);

            }
        });





    }


}