Room Persistence Library 로 샘플을 시도하고 있습니다 . 엔티티를 만들었습니다.

@Entity
public class Agent {
    @PrimaryKey
    public String guid;
    public String name;
    public String email;
    public String password;
    public String phone;
    public String licence;
}

DAO 클래스 생성 :

@Dao
public interface AgentDao {
    @Query("SELECT COUNT(*) FROM Agent where email = :email OR phone = :phone OR licence = :licence")
    int agentsCount(String email, String phone, String licence);

    @Insert
    void insertAgent(Agent agent);
}

데이터베이스 클래스 생성 :

@Database(entities = {Agent.class}, version = 1)
public abstract class AppDatabase extends RoomDatabase {
    public abstract AgentDao agentDao();
}

Kotlin에서 아래 하위 클래스를 사용하여 노출 된 데이터베이스 :

class MyApp : Application() {

    companion object DatabaseSetup {
        var database: AppDatabase? = null
    }

    override fun onCreate() {
        super.onCreate()
        MyApp.database =  Room.databaseBuilder(this, AppDatabase::class.java, "MyDatabase").build()
    }
}

내 활동에서 아래 기능을 구현했습니다.

void signUpAction(View view) {
        String email = editTextEmail.getText().toString();
        String phone = editTextPhone.getText().toString();
        String license = editTextLicence.getText().toString();

        AgentDao agentDao = MyApp.DatabaseSetup.getDatabase().agentDao();
        //1: Check if agent already exists
        int agentsCount = agentDao.agentsCount(email, phone, license);
        if (agentsCount > 0) {
            //2: If it already exists then prompt user
            Toast.makeText(this, "Agent already exists!", Toast.LENGTH_LONG).show();
        }
        else {
            Toast.makeText(this, "Agent does not exist! Hurray :)", Toast.LENGTH_LONG).show();
            onBackPressed();
        }
    }

불행히도 위의 방법을 실행하면 아래 스택 추적과 충돌합니다.

    FATAL EXCEPTION: main
 Process: com.example.me.MyApp, PID: 31592
java.lang.IllegalStateException: Could not execute method for android:onClick
    at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:293)
    at android.view.View.performClick(View.java:5612)
    at android.view.View$PerformClick.run(View.java:22288)
    at android.os.Handler.handleCallback(Handler.java:751)
    at android.os.Handler.dispatchMessage(Handler.java:95)
    at android.os.Looper.loop(Looper.java:154)
    at android.app.ActivityThread.main(ActivityThread.java:6123)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:757)
 Caused by: java.lang.reflect.InvocationTargetException
    at java.lang.reflect.Method.invoke(Native Method)
    at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288)
    at android.view.View.performClick(View.java:5612) 
    at android.view.View$PerformClick.run(View.java:22288) 
    at android.os.Handler.handleCallback(Handler.java:751) 
    at android.os.Handler.dispatchMessage(Handler.java:95) 
    at android.os.Looper.loop(Looper.java:154) 
    at android.app.ActivityThread.main(ActivityThread.java:6123) 
    at java.lang.reflect.Method.invoke(Native Method) 
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:757) 
 Caused by: java.lang.IllegalStateException: Cannot access database on the main thread since it may potentially lock the UI for a long periods of time.
    at android.arch.persistence.room.RoomDatabase.assertNotMainThread(RoomDatabase.java:137)
    at android.arch.persistence.room.RoomDatabase.query(RoomDatabase.java:165)
    at com.example.me.MyApp.RoomDb.Dao.AgentDao_Impl.agentsCount(AgentDao_Impl.java:94)
    at com.example.me.MyApp.View.SignUpActivity.signUpAction(SignUpActivity.java:58)
    at java.lang.reflect.Method.invoke(Native Method) 
    at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288) 
    at android.view.View.performClick(View.java:5612) 
    at android.view.View$PerformClick.run(View.java:22288) 
    at android.os.Handler.handleCallback(Handler.java:751) 
    at android.os.Handler.dispatchMessage(Handler.java:95) 
    at android.os.Looper.loop(Looper.java:154) 
    at android.app.ActivityThread.main(ActivityThread.java:6123) 
    at java.lang.reflect.Method.invoke(Native Method) 
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:757) 

그 문제는 메인 스레드에서 db 작업을 실행하는 것과 관련된 것 같습니다. 그러나 위 링크에 제공된 샘플 테스트 코드는 별도의 스레드에서 실행되지 않습니다.

@Test
    public void writeUserAndReadInList() throws Exception {
        User user = TestUtil.createUser(3);
        user.setName("george");
        mUserDao.insert(user);
        List<User> byName = mUserDao.findUsersByName("george");
        assertThat(byName.get(0), equalTo(user));
    }

여기에 빠진 게 있나요? 충돌없이 실행하려면 어떻게해야합니까? 제안 해주세요.

답변

private static class AgentAsyncTask extends AsyncTask<Void, Void, Integer> {

    //Prevent leak
    private WeakReference<Activity> weakActivity;
    private String email;
    private String phone;
    private String license;

    public AgentAsyncTask(Activity activity, String email, String phone, String license) {
        weakActivity = new WeakReference<>(activity);
        this.email = email;
        this.phone = phone;
        this.license = license;
    }

    @Override
    protected Integer doInBackground(Void... params) {
        AgentDao agentDao = MyApp.DatabaseSetup.getDatabase().agentDao();
        return agentDao.agentsCount(email, phone, license);
    }

    @Override
    protected void onPostExecute(Integer agentsCount) {
        Activity activity = weakActivity.get();
        if(activity == null) {
            return;
        }

        if (agentsCount > 0) {
            //2: If it already exists then prompt user
            Toast.makeText(activity, "Agent already exists!", Toast.LENGTH_LONG).show();
        } else {
            Toast.makeText(activity, "Agent does not exist! Hurray :)", Toast.LENGTH_LONG).show();
            activity.onBackPressed();
        }
    }
}

new AgentAsyncTask(this, email, phone, license).execute();

MyApp.database =  Room.databaseBuilder(this, AppDatabase::class.java, "MyDatabase").allowMainThreadQueries().build()

// Step 1: add `suspend` to your fun
suspend fun roomFun(...): Int
suspend fun notRoomFun(...) = withContext(Dispatchers.IO) { ... }

// Step 2: launch from coroutine scope
private fun myFun() {
    lifecycleScope.launch { // coroutine on Main
        val queryResult = roomFun(...) // coroutine on IO
        doStuff() // ...back on Main
    }
}

// lifecycleScope:
implementation 'androidx.lifecycle:lifecycle-runtime-ktx:2.2.0-alpha04'

// viewModelScope:
implementation 'androidx.lifecycle:lifecycle-viewmodel-ktx:2.2.0-alpha04'

Observable.just(db)
          .subscribeOn(Schedulers.io())
          .subscribe { db -> // database operation }

/**
 *  Insert and get data using Database Async way
 */
AsyncTask.execute(new Runnable() {
    @Override
    public void run() {
        // Insert Data
        AppDatabase.getInstance(context).userDao().insert(new User(1,"James","Mathew"));

        // Get Data
        AppDatabase.getInstance(context).userDao().getAllUsers();
    }
});

 AsyncTask.execute(() -> //run your query here );

    doAsync {
        Application.database.myDAO().insertUser(user)
    }