Question

01-17 14：25：21.567 5084-5084 /？ E / AndroidRuntime：致命异常：主要处理：com.example.harv.swat，PID：5084 java.lang.RuntimeException：无法启动活动 ComponentInfo {com.example.harv.swat / com.example.harv.swat.HomeActivity}： java.lang.RuntimeException：无法找到实现 com.example.harv.swat.model.AppDatabase。 AppDatabase_Impl没有存在在android.app.ActivityThread.performLaunchActivity（ActivityThread.java:2696）在android.app.ActivityThread.handleLaunchActivity（ActivityThread.java:2757）在android.app.ActivityThread.-wrap12（ActivityThread.java）在android.app.ActivityThread $ H.handleMessage（ActivityThread.java:1504）在android.os.Handler.dispatchMessage（Handler.java:102）在android.os.Looper.loop（Looper.java:163）在android.app.ActivityThread.main（ActivityThread.java:6237） at java.lang.reflect.Method.invoke（Native Method）在com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit.java:877）在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:767）引起：java.lang.RuntimeException：无法找到实现 com.example.harv.swat.model.AppDatabase。 AppDatabase_Impl没有存在在android.arch.persistence.room.Room.getGeneratedImplementation（Room.java:92）在android.arch.persistence.room.RoomDatabase $ Builder.build（RoomDatabase.java:454）在com.example.harv.swat.model.Db。（Db.java:16）在com.example.harv.swat.model.Db.getInstance（Db.java:20）在com.example.harv.swat.HomeActivity.onCreate（HomeActivity.java:28）在android.app.Activity.performCreate（Activity.java:6847）在android.app.Instrumentation.callActivityOnCreate（Instrumentation.java:1119）在android.app.ActivityThread.performLaunchActivity（ActivityThread.java:2649）在android.app.ActivityThread.handleLaunchActivity（ActivityThread.java:2757）在android.app.ActivityThread.-wrap12（ActivityThread.java）在android.app.ActivityThread $ H.handleMessage（ActivityThread.java:1504）在android.os.Handler.dispatchMessage（Handler.java:102）在android.os.Looper.loop（Looper.java:163）在android.app.ActivityThread.main（ActivityThread.java:6237） at java.lang.reflect.Method.invoke（Native Method）在com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit.java:877）在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:767）

public class Db {
AppDatabase adb;
private static Db db;

private Db(Context context){
    adb = Room.databaseBuilder(context,
            AppDatabase.class, "swat").allowMainThreadQueries().build();
}
public static Db getInstance(Context context){
    if(db==null){
        db = new Db(context);
    }
    return db;
}
public MyDAO getDao(){
    return adb.userDao();
}}

DOA课程

@Dao
public interface MyDAO {
@Query("SELECT * FROM content")
List<Content> getAll();

@Query("SELECT * FROM content WHERE id IN (:userIds)")
List<Content> loadAllByIds(int[] userIds);

/*@Query("SELECT * FROM user WHERE first_name LIKE :first AND "
        + "last_name LIKE :last LIMIT 1")
Content findByName(String first, String last);*/

@Insert
void insertAll(Content... users);

@Delete
void delete(Content user);}

Gradle文件

dependencies {
implementation fileTree(dir: 'libs', include: ['*.jar'])
implementation "org.jetbrains.kotlin:kotlin-stdlib-jre7:$kotlin_version"
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'

// ViewModel and LiveData
implementation "android.arch.lifecycle:extensions:1.0.0"
implementation "android.arch.lifecycle:common-java8:1.0.0"
//annotationProcessor "android.arch.lifecycle:compiler:1.0.0"

// Room
implementation "android.arch.persistence.room:runtime:1.0.0"
annotationProcessor "android.arch.persistence.room:compiler:1.0.0"

// Test helpers for Room
testImplementation "android.arch.persistence.room:testing:1.0.0"
}

Answer 1

更改时，可能无法重新生成文件。也许尝试重建项目：Build - ＆gt;重建

为什么Room告诉我AppDatabase_Impl不存在错误？

1 个答案: