Question

我遇到以下问题：我很确定代码是干净的，但是仿真器仍然没有显示我尝试保存的数据。我检查了两次，无法弄清楚是什么。也许你有个主意。

这是我的AppDatabase类：

@Database(entities = {Projekt.class}, version = 1, exportSchema = false) 
@TypeConverters({Converters.class}) public abstract class AppDatabase  
extends RoomDatabase {
public abstract RoomDAO getRoomDAO(); 
}

这是我的DAO界面：

@Dao
public interface RoomDAO {

@Insert
public void insert(Projekt... projekte);

@Update
public void update(Projekt... projekte);

@Delete
public void delete(Projekt... projekte);

@Query("SELECT * FROM projekt")
public List<Projekt> getProjektname();

@Query("SELECT * FROM projekt WHERE standort= :name")
public Projekt getProjektWithId(String name);

}

这是我的MainActivity：

private static final int CREATE_PROJEKT = 1;
private static final int UPDATE_PROJEKT = 2;


private RoomDAO mRoomDAO;
private RecyclerView ProjekteRecyclerview;
private ProjektRecyclerAdapter mProjektRecyclerAdapter;
private FloatingActionButton mAddProjektFloatingActionButton;




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

    mRoomDAO = Room.databaseBuilder(this, AppDatabase.class, "db-projekte")
            .allowMainThreadQueries()
            .build()
            .getRoomDAO();

    ProjekteRecyclerview = findViewById(R.id.ProjektRecyclerView);
    ProjekteRecyclerview.setLayoutManager(new LinearLayoutManager(this));
    mAddProjektFloatingActionButton = findViewById(R.id.addProjektFloatingActionButton);

    int colors [] = {ContextCompat.getColor(this, R.color.colorAccent),
            ContextCompat.getColor(this, android.R.color.holo_red_light),
            ContextCompat.getColor(this, android.R.color.holo_orange_light),
            ContextCompat.getColor(this, android.R.color.holo_green_light),
            ContextCompat.getColor(this, android.R.color.holo_blue_dark),
            ContextCompat.getColor(this, android.R.color.holo_purple)};

    mProjektRecyclerAdapter = new ProjektRecyclerAdapter(this, new ArrayList<Projekt>(), colors);
    mProjektRecyclerAdapter.addActionCallback(new ProjektRecyclerAdapter.ActionCallback() {
        @Override
        public void onLongClickListener(Projekt projekt) {
            Intent intent = new Intent (MainActivity.this, UpdateProjektActivity.class);
            intent.putExtra(UpdateProjektActivity.EXTRA_PROJEKT_ID, projekt.getStandort());
            startActivityForResult(intent, UPDATE_PROJEKT);
        }
    });

    ProjekteRecyclerview.setAdapter(mProjektRecyclerAdapter);

    mAddProjektFloatingActionButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Intent intent = new Intent(MainActivity.this, CreateProjektActivity.class);
            startActivityForResult(intent, CREATE_PROJEKT);
        }
    });

    loadProjekte();
}


private void loadProjekte(){
    mProjektRecyclerAdapter.updateData(mRoomDAO.getProjektname());
}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    if(requestCode == CREATE_PROJEKT && resultCode == RESULT_OK){
        loadProjekte();
    } else if (requestCode == UPDATE_PROJEKT && resultCode == RESULT_OK){
        loadProjekte();
    }
}
}

这是我的RecylcerAdapter，我认为这是问题所在。

public class ProjektRecyclerAdapter extends RecyclerView.Adapter<ProjektRecyclerAdapter.ViewHolder> {

interface ActionCallback {
    void onLongClickListener(Projekt projekt);
}

private Context context;
private List<Projekt> projektList;
private int[] colors;
private ActionCallback mActionCallback;

ProjektRecyclerAdapter(Context context, List<Projekt> projektList, int[] colors){
    this.context = context;
    this.projektList = projektList;
    this.colors = colors;
}

@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType){
    View view = LayoutInflater.from(context).inflate(R.layout.item_recylcer_projekt, parent, false);
    return new ViewHolder(view);
}

@Override
public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
    holder.bindData(position);
}


@Override
public int getItemCount() {
    return projektList.size();
}

void updateData(List<Projekt> projekte){
    this.projektList = projekte;
    notifyDataSetChanged();
}

//ViewHolder Class
class ViewHolder extends RecyclerView.ViewHolder implements View.OnLongClickListener{

    private TextView mNameTextView;
    private TextView mInitialsTextView;
    private GradientDrawable mInitialsBackground;

    ViewHolder(View itemView){
        super(itemView);
        itemView.setOnLongClickListener(this);

        mInitialsTextView = itemView.findViewById(R.id.initialsTextView);
        mNameTextView = itemView.findViewById(R.id.nameTextView);
        mInitialsBackground = (GradientDrawable) mInitialsTextView.getBackground();
    }

    void bindData(int position){
        Projekt projekt = projektList.get(position);

        String fullName = projekt.getProjektname() + " " + projekt.getArbeitername();
        mNameTextView.setText(fullName);

        String initial = projekt.getProjektname().toUpperCase().substring(0, 1);
        mInitialsTextView.setText(initial);


        mInitialsBackground.setColor(colors[position % colors.length]);
    }




    @Override
    public boolean onLongClick(View v) {
        if(mActionCallback != null){
            mActionCallback.onLongClickListener(projektList.get(getAdapterPosition()));
        }
        return true;
    }
}

void addActionCallback(ActionCallback actionCallbacks){
    mActionCallback = actionCallbacks;
}

}

这是我的buil.gradle：

apply plugin: 'com.android.application'

android {
compileSdkVersion 26
defaultConfig {
    applicationId "com.adesso.lklein.roomcontacttest"
    minSdkVersion 16
    targetSdkVersion 26
    versionCode 1
    versionName "1.0"
    testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"

}
buildTypes {
    release {
        minifyEnabled false
        proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
    }
}
}

dependencies {
implementation fileTree(include: ['*.jar'], dir: 'libs')
implementation 'com.android.support:appcompat-v7:26.1.0'
implementation 'com.android.support.constraint:constraint-layout:1.0.2'
testImplementation 'junit:junit:4.12'
androidTestImplementation 'com.android.support.test:runner:1.0.1'
androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.1'
implementation 'android.arch.persistence.room:runtime:1.0.0'
annotationProcessor "android.arch.persistence.room:compiler:1.0.0"
implementation 'com.android.support:design:27.0.2'
}

构建良好，没有错误或任何警告。即使在Logcat中，当我单击“保存”按钮时，它也不会显示任何内容。知道这是什么吗？

预先感谢

Answer 1

尝试这种方式..并根据更改代码。进行如下所示的应用程序级活动

public class AppActivity extends Application {

static AppDatabase db;

@Override
public void onCreate() {
    super.onCreate();
    db = Room.databaseBuilder(getApplicationContext(), AppDatabase.class, "database-name").build();
}

public static AppDatabase getDatabase() {
    return db;
}
}

并且此活动将android清单文件定义到应用程序标签中。如下所示。

        android:name=".db.AppActivity"

之后创建数据库..

@Database(entities = {MyTable.class}, version = 1)
public abstract class AppDatabase extends RoomDatabase {
public abstract MyTableDao getTableDao();
}

制作道..

@Dao
public interface MyTableDao {
@Insert
void insertData(MyTable myTable);

@Query("SELECT * FROM MyTable where id=:id and ItemPrice=:price")
List<MyTable> getData(int id,int price);

}

然后执行如下所示的db操作。

        AppActivity.getDatabase().getTableDao().insertData(user); // pass object

Android Room不显示存储的数据

1 个答案: