java - 如何确定 setPersistenceEnabled 是否已启用？

Question

一切正常。应用程序运行后，我通过多任务查看器按主页并返回到应用程序，它运行良好。但是，一旦它运行，并且我从抽屉中按下它的图标，它就会崩溃，因为它在运行时再次调用“setPersistenceEnabled()”。那么，在尝试启用它之前如何检查它是否已启用呢？我的代码:

public class SplashActivity extends AppCompatActivity {

private FirebaseUser firAuth;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    getInstance().setPersistenceEnabled(true);


    firAuth = FirebaseAuth.getInstance().getCurrentUser();

    if (firAuth!=null) {
        // User is signed in.
        Intent intent = new Intent(this, Identificador.class);
        startActivity(intent);
        finish();

    } else {
        // No user is signed in.
        Intent intent = new Intent(this, LoginActivity.class);
        startActivity(intent);
        finish();
    }

};


}

Answer 1

我建议您使用以下代码行:

private static boolean calledAlready = false;
if (!calledAlready) {
    FirebaseDatabase.getInstance().setPersistenceEnabled(true);
    calledAlready = true;
}