public class Choose_Action extends Activity{

Button button;
EditText editText;
TextView text;
@Override
protected void onCreate(Bundle savedInstanceState){
    super.onCreate(savedInstanceState);
    requestWindowFeature(Window.FEATURE_NO_TITLE);
    this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
    setContentView(R.layout.choose_action_layout);

    button = (Button)findViewById(R.id.btn);
    editText = (EditText)findViewById(R.id.edit);
    text = (TextView)findViewById(R.id.textview);

}

public void Check(View v) {
    text.setText(editText.getText().toString());
}

public class MainActivity extends Activity {

EditText pass;
EditText user;

@Override
protected void onCreate(Bundle savedInstanceState){

    super.onCreate(savedInstanceState);
    requestWindowFeature(Window.FEATURE_NO_TITLE);
    this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
    setContentView(R.layout.main_layout);

    pass = (EditText)findViewById(R.id.password);
    user = (EditText)findViewById(R.id.username);

}

public void LogIn(View v){
    AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
    LayoutInflater inflater = this.getLayoutInflater();
    final View dialogView = inflater.inflate(R.layout.dialog_layout, null);
    builder.setView(dialogView);


    builder.setPositiveButton("Войти", new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog, int arg1) {
            if(pass.getText().toString()=="pass" && user.getText().toString()=="user"){
            startActivity(new Intent(MainActivity.this, Choose_Action.class));}

            startActivity(new Intent(MainActivity.this, Choose_Action.class));

        }
    });
    builder.setNegativeButton("Отмена", new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog, int arg1) {
            //startActivity(new Intent(MainActivity.this, MainActivity.class));
        }
    });
    builder.show();

}