我使用room创建了简单的脱机数据库,但出现此错误
原因:java.lang.RuntimeException:找不到以下实现: com.test.test.AppDatabase.SplashScreenActivity_AppDatabase_Impl可以 不存在
代码
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_splash_screen);
AppDatabase appDatabase = Room.databaseBuilder(getApplicationContext(), AppDatabase.class, "testDatabase").build();
Categories category = new Categories();
category.setId(0);
category.setId(1);
category.setCategoryName("Te");
category.setCategoryName("Test");
appDatabase.categoriesDao().insertAll(category);
}
@Entity
class Categories {
@PrimaryKey
int id;
@ColumnInfo(name = "category_name")
String categoryName;
void setId(int id) {
this.id = id;
}
void setCategoryName(String categoryName) {
this.categoryName = categoryName;
}
}
@Dao
public interface CategoriesDao {
@Insert
void insertAll(Categories... categories);
}
@Database(entities = {Categories.class}, version = 1)
abstract class AppDatabase extends RoomDatabase {
abstract CategoriesDao categoriesDao();
}
Build.gradle
apply plugin: 'com.android.application'
android {
compileSdkVersion 28
defaultConfig {
applicationId "com.**********"
minSdkVersion 19
targetSdkVersion 28
versionCode 1
versionName "1.0"
testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
multiDexEnabled true
}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
}
}
compileOptions {
sourceCompatibility JavaVersion.VERSION_1_8
targetCompatibility JavaVersion.VERSION_1_8
}
}
dependencies {
implementation fileTree(dir: 'libs', include: ['*.jar'])
implementation 'androidx.appcompat:appcompat:1.1.0'
implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
implementation 'com.android.support:multidex:1.0.3'
testImplementation 'junit:junit:4.12'
androidTestImplementation 'androidx.test.ext:junit:1.1.1'
androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'
//Material Design
implementation 'com.google.android.material:material:1.2.0-alpha01'
//Butter Knife
implementation 'com.jakewharton:butterknife:10.2.0'
annotationProcessor 'com.jakewharton:butterknife-compiler:10.2.0'
//Volley
implementation 'com.android.volley:volley:1.1.1'
//Room
implementation "androidx.room:room-runtime:2.2.0"
}
apply plugin: 'com.jakewharton.butterknife'
我在此网站上找到了许多解决方案,但都无法与我合作,谢谢。
答案 0 :(得分:2)
... else {
mark[r] =true ;
choose_elem_aux l n mark tmp ;
} ...
let choose l =
nth l (Random.int (List.length l)) ;;
let rec choose_elem_aux l n tmp =
if n=0 then tmp
else
let r=choose l in if List.mem r tmp then
choose_elem_aux l n tmp else choose_elem_aux l (n-1) (r::tmp) ;;
let rec choose_elements l n =
choose_elem_aux l n [] ;;
文件中添加了choose_elements [1...10_000] 7 ;;
string s = "I love dogs";
int i, j = 0;
List<char> array1 = new List<char>();
List<char> array2 = new List<char>();
for (i = 0; i < s.Length; i++)
{
if (s.Length == j)
break;
if (Char.IsLetter(s[i]))
{
array1.Add(s[i]);
}
else
{
for (j = i; j < s.Length; j++)
{
if (Char.IsLetter(s[j]))
{
array2.Add(s[i]);
}
if (!Char.IsLetter(s[j]) || j == s.Length - 1)
{
if (array1.Count >= array2.Count)
{
array2.Clear();
}
else
{
array1.Clear();
array1.AddRange(array2);
array2.Clear();
}
}
}
}
} // How to convert array1 into String ?
annotationProcessor
类在build.gradle
内部成为静态对象,例如:annotationProcessor "androidx.room:room-compiler:2.2.0"
或为AppDatabase
而不是内部类创建单独的文件