我的应用程序崩溃了我正在尝试读取预构建的数据库并从那里加载列，但目前，它在启动时崩溃，并认为它与我的 DHhandler 以及它如何设置 GetJobList 有关，但我对 Android 和一般编程，所以我不完全确定
DBhandler 在下面
package com.example.joelg.clapp;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.database.sqlite.SQLiteOpenHelper;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.ArrayList;
/**
* Created by joelg on 22/10/2017.
*/
public class IntDataBaseHelper extends SQLiteOpenHelper{
private static String DB_PATH ="C:\\Users\\joelg\\AndroidStudioProjects\\CLAPP\\app\\build\\intermediates\\assets";
private static String DB_NAME = "JobList";
private static String DB_COLUMN = " JobNM";
private static String DB_TABLE = "Job";
private static String DB_JOB_IS_DONE = "JobComplete";
private SQLiteDatabase JobListDatabase;
private final Context jobContext;
/**
* constructor t
*/
public IntDataBaseHelper (Context context) {
super (context, DB_NAME,null, 1);
this.jobContext = context;
}
public void createDataBase() throws IOException {
boolean dbExist = checkDataBase();
if(dbExist){
//do nothing database already exists
}else{
// calling this method will create an empty database
this.getReadableDatabase();
try {
copyDataBase();
} catch (IOException e){
throw new Error("Error copying database");
}
}
}
// check if database exists to avoid recopying it
private boolean checkDataBase (){
SQLiteDatabase checkDB = null;
try{
String JobListPath = DB_PATH + DB_NAME;
checkDB = SQLiteDatabase.openDatabase(JobListPath, null,
SQLiteDatabase.OPEN_READONLY);
}catch(SQLiteException e){
// database doesnt exist yet
}
if(checkDB !=null){
checkDB.close();
}
return checkDB !=null ? true : false;
}
// copies db from local assets file, were it can be accessed and handled
private void copyDataBase() throws IOException {
// open local database as the input stream
InputStream JobInput = jobContext.getAssets().open(DB_NAME);
// path to the just created empty database
String OutFileName = DB_PATH + DB_NAME;
// open the empty db as the output stra,
OutputStream myOutPut = new FileOutputStream(OutFileName);
// transfer bytes from the input file to the output file
byte[] buffer = new byte[1024];
int length;
while ((length = JobInput.read(buffer))>0){
myOutPut.write(buffer,0,length);
}
myOutPut.flush();
myOutPut.close();
JobInput.close();
}
public void openDataBase() throws SQLiteException {
// open the database
String JobListPath = DB_PATH+DB_NAME;
JobListDatabase =
SQLiteDatabase.openDatabase(JobListPath,null,SQLiteDatabase.OPEN_READONLY);
}
// Getting Job Count
public ArrayList<String> getJobList() {
ArrayList<String> JobList = new ArrayList<>();
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.query(DB_TABLE,new String[]
{DB_COLUMN},null,null,null,null,null);
while(cursor.moveToNext()){
int index = cursor.getColumnIndex(DB_COLUMN);
JobList.add(cursor.getString(index));
}
cursor.close();
db.close();
return JobList;
}
@Override
public synchronized void close(){
if(JobListDatabase !=null){
JobListDatabase.close();
super.close();
}
}
@Override
public void onCreate(SQLiteDatabase db) {
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
}
这是 logcat 输出
10-24 03:07:05.081 11072-11072/com.example.joelg.clapp E/SQLiteLog: (1) no such table: job
10-24 03:07:05.084 11072-11072/com.example.joelg.clapp E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.joelg.clapp, PID: 11072
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.joelg.clapp/com.example.joelg.clapp.MainActivity}: android.database.sqlite.SQLiteException: no such table: job (code 1): , while compiling: SELECT jobNM FROM job
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2817)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2892)
at android.app.ActivityThread.-wrap11(Unknown Source:0)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1593)
at android.os.Handler.dispatchMessage(Handler.java:105)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6541)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)
Caused by: android.database.sqlite.SQLiteException: no such table: job (code 1): , while compiling: SELECT jobNM FROM job
at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method)
at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:889)
at android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:500)
at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:588)
at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:58)
at android.database.sqlite.SQLiteQuery.<init>(SQLiteQuery.java:37)
at android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:44)
at android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:1318)
at android.database.sqlite.SQLiteDatabase.queryWithFactory(SQLiteDatabase.java:1165)
at android.database.sqlite.SQLiteDatabase.query(SQLiteDatabase.java:1036)
at android.database.sqlite.SQLiteDatabase.query(SQLiteDatabase.java:1204)
at
com.example.joelg.clapp.IntDataBaseHelper.getJobList(IntDataBaseHelper.java:128)
at
com.example.joelg.clapp.MainActivity.onCreate(MainActivity.java:46)
at
android.app.Activity.performCreate(Activity.java:6975)
at
android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1213)
at
android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2770)
at
android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2892)
at
android.app.ActivityThread.-wrap11(Unknown Source:0)
at
android.app.ActivityThread$H.handleMessage(ActivityThread.java:1593)
at
android.os.Handler.dispatchMessage(Handler.java:105)
at
android.os.Looper.loop(Looper.java:164)
at
android.app.ActivityThread.main(ActivityThread.java:6541)
at
java.lang.reflect.Method.invoke(Native Method)
at
com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
at
com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)
这是作业数据库文件的位置
这是最新的错误logcat
[ 10-24 05:22:39.920
1508:
2079 D/ ]
SurfaceInterface::setAsyncMode: set async mode 1
10-24 05:22:39.925 1611-1631/? E/ResourcesManager: failed to add asset path
/data/app/com.example.joelg.clapp-0JSJFIAy0bMCNOuIEgUs3g==/base.apk
10-24 05:22:39.925 1611-1631/? E/ResourcesManager: failed to add asset path
/data/app/com.example.joelg.clapp-0JSJFIAy0bMCNOuIEgUs3g==/base.apk
10-24 05:22:39.925 1611-1631/? E/ResourcesManager: failed to add asset path
/data/app/com.example.joelg.clapp-0JSJFIAy0bMCNOuIEgUs3g==/base.apk
10-24 05:22:39.938 1611-1631/? E/ResourcesManager: failed to add asset path
/data/app/com.example.joelg.clapp-0JSJFIAy0bMCNOuIEgUs3g==/base.apk
10-24 05:22:40.523 1611-1628/? E/ResourcesManager: failed to add asset path
/data/app/com.example.joelg.clapp-0JSJFIAy0bMCNOuIEgUs3g==/base.apk
10-24 05:22:40.523 1611-1628/? E/ResourcesManager: failed to add asset path
/data/app/com.example.joelg.clapp-0JSJFIAy0bMCNOuIEgUs3g==/base.apk
10-24 05:22:42.973 1508-1598/? E/TaskPersister: File error accessing recents
directory (directory doesn't exist?).
10-24 05:22:53.636 1508-1598/? E/TaskPersister: File error accessing recents
directory (directory doesn't exist?).
10-24 05:22:54.924 1508-1521/? E/memtrack: Couldn't load memtrack module
10-24 05:23:26.999 1508-1521/? E/memtrack: Couldn't load memtrack module
10-24 05:23:27.010 1508-1521/? E/memtrack: Couldn't load memtrack module
10-24 05:23:39.285 1508-1525/? E/BatteryStatsService: modem info is invalid:
`ModemActivityInfo{ mTimestamp=0 mSleepTimeMs=0 mIdleTimeMs=0 mTxTimeMs[]=
[0, 0, 0, 0, 0] mRxTimeMs=0 mEnergyUsed=0}`
10-24 05:23:43.109 1508-1521/? E/memtrack: Couldn't load memtrack module
10-24 05:24:00.005 1508-1521/? E/memtrack: Couldn't load memtrack module
最新的 logcat 输出
10-24 12:01:30.319 2669-2669/? E/SQLiteLog: (14) cannot open file at line 35648 of [036ebf729e]
10-24 12:01:30.319 2669-2669/? E/SQLiteLog: (14) os_unix.c:35648: (2) open(/data/user/0/com.example.joelg.clapp/databases/JobList) -
10-24 12:01:30.320 2669-2669/? E/SQLiteDatabase: Failed to open database '/data/user/0/com.example.joelg.clapp/databases/JobList'.
android.database.sqlite.SQLiteCantOpenDatabaseException: unknown error (code 14): Could not open database
at android.database.sqlite.SQLiteConnection.nativeOpen(Native Method)
at android.database.sqlite.SQLiteConnection.open(SQLiteConnection.java:209)
at android.database.sqlite.SQLiteConnection.open(SQLiteConnection.java:193)
at android.database.sqlite.SQLiteConnectionPool.openConnectionLocked(SQLiteConnectionPool.java:463)
at android.database.sqlite.SQLiteConnectionPool.open(SQLiteConnectionPool.java:185)
at android.database.sqlite.SQLiteConnectionPool.open(SQLiteConnectionPool.java:177)
at android.database.sqlite.SQLiteDatabase.openInner(SQLiteDatabase.java:808)
at android.database.sqlite.SQLiteDatabase.open(SQLiteDatabase.java:793)
at android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:696)
at android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:671)
at com.example.joelg.clapp.CopyDBFromAssets.checkDataBase(CopyDBFromAssets.java:94)
at com.example.joelg.clapp.CopyDBFromAssets.createDataBase(CopyDBFromAssets.java:25)
at com.example.joelg.clapp.MainActivity.onCreate(MainActivity.java:25)
at android.app.Activity.performCreate(Activity.java:6975)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1213)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2770)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2892)
at android.app.ActivityThread.-wrap11(Unknown Source:0)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1593)
at android.os.Handler.dispatchMessage(Handler.java:105)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6541)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)
10-24 12:01:30.322 2669-2669/? E/CHECKASSET: Asset JobListcould not be found. Assets that exists are:- CleanIngListTemplate.db.sqbpro JobList.db JobList.db.sqbpro JobList.sqbpro images webkit
10-24 12:01:30.322 2669-2669/? E/CREATEDB: Error getting asset JobList
10-24 12:01:30.325 2669-2669/? E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.joelg.clapp, PID: 2669
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.joelg.clapp/com.example.joelg.clapp.MainActivity}: java.lang.RuntimeException: No Usable Database exists or was copied from the assets.
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2817)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2892)
at android.app.ActivityThread.-wrap11(Unknown Source:0)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1593)
at android.os.Handler.dispatchMessage(Handler.java:105)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6541)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)
Caused by: java.lang.RuntimeException: No Usable Database exists or was copied from the assets.
at com.example.joelg.clapp.MainActivity.onCreate(MainActivity.java:34)
at android.app.Activity.performCreate(Activity.java:6975)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1213)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2770)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2892)
at android.app.ActivityThread.-wrap11(Unknown Source:0)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1593)
at android.os.Handler.dispatchMessage(Handler.java:105)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6541)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)
最佳答案
根据评论回复问题。
1) 是至关重要的 复制到 assets 文件夹中的文件与数据库具有完全相同的名称。所以如果要调用数据库职位列表 ，那么它必须是 assets 文件夹中的文件名。
2)在我开始写代码之前，先解释一下困惑。如果事情不完全正确，这是一个双重打击。这与创建数据库的情况无关。先单行this.getReadableDatabase();在 createDatabase IntDataBaseHelper 的方法如果数据库不存在，将运行。但是，另外，即使这不会运行(例如，注释掉)，因为您已经创建了 IntDataBaseHelper 的实例类，那么任何打开数据库的尝试也会尝试创建它。在 onCreate 中没有代码的情况下方法结果将是一个实际上没有表的空数据库*(表 sqlite_master 和 android_metadata 将存在，但它们是系统类型表)**
因此，我决定将数据库的创建/副本从 DBHelper 中分离出来，并希望使代码问题更具描述性。
所以我建议你使用的代码。
首先有一个新类，我称之为 CopyDBFromAssets .这基本上是来自 IntDatabaseHelper 的代码但写得比较啰嗦。有一种新方法checkAssetExists ，它的名字应该是不言自明的重新分级它的使用。
调用 MainActivity 有点不同。而不是获得 IntDatabaseHelper 的实例.代码最初调用 createDatabase新的 CopyDBFromAssets 中的方法类，它返回一个 boolean 值。
如果 真实 然后是
IntDatabaseHelper 的实例已创建，一切都应该没问题。CopyDBFromAssets
1) 新建类 CopyDBFromAssets.java 然后复制以下代码:-
public class CopyDBFromAssets {
boolean copied = false;
public static boolean createDataBase(Context context, String databasename) {
boolean copied = false;
boolean dbExist = checkDataBase(context, databasename);
if(!dbExist) {
// calling this method will create an empty database
// which will hopefully be overidden, if not then
// empty database will exist ?????????
//this.getReadableDatabase(); <<<<< NOTE Commented out as empty db with no tables is useless
if (!checkAssetExists(context, databasename, "")) {
Log.e("CREATEDB", "Error getting asset " + databasename);
} else {
return copyDataBase(context, databasename);
}
return false;
}
return true;
}
private static boolean checkAssetExists(Context context, String assetfile, String path) {
boolean rv = false; // assume asset file doesn't exist
String[] assetsfound = new String[]{};
// Get the list of assets at the given path
try {
assetsfound = context.getAssets().list(path);
} catch (IOException e) {
Log.e("CHECKASSET","IO Exception when checking for the asset file." + e.getMessage());
return false;
}
// Check to see if the desired asset (passed assetfile) exists
for (String s: assetsfound) {
if (s.equals(assetfile)) {
rv = true;
break;
}
}
if (rv) {
Log.d("CHECKASSET", "Asset " + assetfile + "was found.");
} else {
String assetlist = "";
for (String s: assetsfound) {
assetlist = assetlist + " " + s;
}
Log.e("CHECKASSET", "Asset " + assetfile +
"could not be found. Assets that exists are:- " +
assetlist
);
}
// Asset not found lets try ignoring case
if (!rv) {
for (String s: assetsfound) {
if ((s.toLowerCase()).equals(assetfile.toLowerCase())) {
Log.e("CHECKASSET","Found asset as " + assetfile +
" but looking for " + s +
", although they are similar the case is different."
);
}
}
}
return rv;
}
// check if database exists to avoid recopying it
private static boolean checkDataBase (Context context, String database){
SQLiteDatabase checkDB = null;
String dbpath = context.getDatabasePath(database).getPath();
try{
checkDB = SQLiteDatabase.openDatabase(dbpath, null,
SQLiteDatabase.OPEN_READONLY);
} catch(SQLiteException e){
// database doesnt exist yet
}
if(checkDB !=null){
checkDB.close();
}
return checkDB !=null ? true : false;
}
// copies db from local assets file, were it can be accessed and handled
private static boolean copyDataBase(Context context, String databasename) {
InputStream asset;
OutputStream db;
int bytescopied = 0;
int length_read;
int buffersize = 16384;
int blockcount = 0;
boolean rv = false;
try {
asset = context.getAssets().open(databasename);
} catch (IOException e) {
Log.e("COPYDB",
"IO Error opening the asset " +
databasename +
". Error Message was " +
e.getMessage()
);
return false;
}
try {
db = new FileOutputStream(context.getDatabasePath(databasename).getPath());
} catch (IOException e) {
Log.e("COPYDB",
"IO Error opening the output file for the database with path " +
databasename +
". error Message was " +
e.getMessage()
);
try {
asset.close();
} catch (IOException e2) {
Log.e("COPYDB",
"IO Error closing the asset. Message was " + e2.getMessage()
);
}
return false;
}
byte[] buffer = new byte[buffersize];
try {
while ((length_read = asset.read(buffer)) > 0) {
db.write(buffer);
bytescopied = bytescopied + length_read;
blockcount++;
rv = true;
}
} catch (IOException e) {
Log.e("COPYDB",
"IO Error Copying Database. Bytes Copied = "
+ bytescopied +
" in " +
blockcount +
" blocks of " +
buffersize
);
}
Log.d("COPYDB","Succesfully copied Database " + databasename + " from the assets." +
" Number of bytes copied = " + bytescopied +
" in " + blockcount + " blocks of length " + buffersize
);
try {
db.flush();
db.close();
asset.close();
} catch (IOException e) {
Log.e("COPYDB",
"IO Error flushing or closing Database or closing asset."
);
}
return rv;
}
}
IntDataBaseHelper
这是一个精简版，需要注意的一点是DB_NAME、DB_COLUMN和DB_TABLE已更改为
public static final (因为它们在其他地方使用)。这是代码:-
public class IntDataBaseHelper extends SQLiteOpenHelper {
private static String DB_PATH ="C:\\Users\\joelg\\AndroidStudioProjects\\CLAPP\\app\\build\\intermediates\\assets";
public static final String DB_NAME = "JobList";
public static final String DB_COLUMN = "JobNM";
public static final String DB_TABLE = "Job";
private static String DB_JOB_IS_DONE = "JobComplete";
private SQLiteDatabase JobListDatabase;
private final Context jobContext;
/**
* constructor t
*/
public IntDataBaseHelper (Context context) {
super (context, DB_NAME,null, 1);
this.jobContext = context;
DB_PATH = jobContext.getDatabasePath(DB_NAME).getPath();
}
public void openDataBase() {
// open the database
String JobListPath = DB_PATH;
JobListDatabase =
SQLiteDatabase.openDatabase(JobListPath,null,SQLiteDatabase.OPEN_READONLY);
}
// Getting Job Count
public ArrayList<String> getJobList() {
ArrayList<String> JobList = new ArrayList<>();
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.query(DB_TABLE,new String[]
{DB_COLUMN},null,null,null,null,null);
while(cursor.moveToNext()){
int index = cursor.getColumnIndex(DB_COLUMN);
JobList.add(cursor.getString(index));
}
cursor.close();
db.close();
return JobList;
}
@Override
public synchronized void close(){
if(JobListDatabase !=null){
JobListDatabase.close();
super.close();
}
}
@Override
public void onCreate(SQLiteDatabase db) {
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
}
主要 Activity
这只是使用上述代码的示例代码，请注意，如果数据库不存在则无法创建，则会发出运行时异常(示例如下):-
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Create the database (only if it doesn't exists)
// does so by copying from the assets
if (CopyDBFromAssets.createDataBase(this,IntDataBaseHelper.DB_NAME)) {
IntDataBaseHelper myhelper = new IntDataBaseHelper(this);
// Get the data from the database
ArrayList<String> jobs = myhelper.getJobList();
for (String s: jobs) {
Log.d("TESTDB","Found Job " + s);
}
} else {
throw new RuntimeException("No Usable Database exists or was copied from the assets.");
}
}
}
运行示例 1(未找到 Assets 文件)
所以首先让我们假设 assets 文件夹中的文件名称为 职位 不是 职位列表 (或 JobList 以外的任何内容)假设刚刚安装了该应用程序。然后运行上述内容将导致以下内容:-
根据 Windows 资源管理器的 Assets 文件夹:-
10-24 20:31:04.994 2346-2346/? E/SQLiteLog: (14) cannot open file at line 30046 of [9491ba7d73]
10-24 20:31:04.994 2346-2346/? E/SQLiteLog: (14) os_unix.c:30046: (2) open(/data/data/mjt.joblist/databases/JobList) -
10-24 20:31:04.994 2346-2346/? E/SQLiteDatabase: Failed to open database '/data/data/mjt.joblist/databases/JobList'.
android.database.sqlite.SQLiteCantOpenDatabaseException: unknown error (code 14): Could not open database
at android.database.sqlite.SQLiteConnection.nativeOpen(Native Method)
at android.database.sqlite.SQLiteConnection.open(SQLiteConnection.java:209)
at android.database.sqlite.SQLiteConnection.open(SQLiteConnection.java:193)
at android.database.sqlite.SQLiteConnectionPool.openConnectionLocked(SQLiteConnectionPool.java:463)
at android.database.sqlite.SQLiteConnectionPool.open(SQLiteConnectionPool.java:185)
at android.database.sqlite.SQLiteConnectionPool.open(SQLiteConnectionPool.java:177)
at android.database.sqlite.SQLiteDatabase.openInner(SQLiteDatabase.java:806)
at android.database.sqlite.SQLiteDatabase.open(SQLiteDatabase.java:791)
at android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:694)
at android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:669)
at mjt.joblist.CopyDBFromAssets.checkDataBase(CopyDBFromAssets.java:93)
at mjt.joblist.CopyDBFromAssets.createDataBase(CopyDBFromAssets.java:25)
at mjt.joblist.MainActivity.onCreate(MainActivity.java:18)
at android.app.Activity.performCreate(Activity.java:5990)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2278)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387)
at android.app.ActivityThread.access$800(ActivityThread.java:151)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5254)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
10-24 20:31:05.004 2346-2346/? E/CHECKASSET: Asset JobListcould not be found. Assets that exists are:- Job images sounds webkit
10-24 20:31:05.004 2346-2346/? E/CREATEDB: Error getting asset JobList
10-24 20:31:05.004 2346-2346/? D/AndroidRuntime: Shutting down VM
--------- beginning of crash
10-24 20:31:05.004 2346-2346/? E/AndroidRuntime: FATAL EXCEPTION: main
Process: mjt.joblist, PID: 2346
java.lang.RuntimeException: Unable to start activity ComponentInfo{mjt.joblist/mjt.joblist.MainActivity}: java.lang.RuntimeException: No Usable Database exists or was copied from the assets.
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2325)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387)
at android.app.ActivityThread.access$800(ActivityThread.java:151)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5254)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
Caused by: java.lang.RuntimeException: No Usable Database exists or was copied from the assets.
at mjt.joblist.MainActivity.onCreate(MainActivity.java:27)
at android.app.Activity.performCreate(Activity.java:5990)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2278)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387)
at android.app.ActivityThread.access$800(ActivityThread.java:151)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5254)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
10-24 20:31:05.008 738-1262/? W/ActivityManager: Force finishing activity 1 mjt.joblist/.MainActivity
以下几行详细说明了该问题:-
10-24 20:31:05.004 2346-2346/? E/CHECKASSET: Asset JobListcould not be found. Assets that exists are:- Job images sounds webkit
10-24 20:31:05.004 2346-2346/? E/CREATEDB: Error getting asset JobList
那是职位列表 找不到，找到的 Assets 是 职位 (错误命名)图像、声音和 webkit(最后三个与此无关)。
运行时异常(第 2 次)也是如此: -
java.lang.RuntimeException: Unable to start activity ComponentInfo{mjt.joblist/mjt.joblist.MainActivity}: java.lang.RuntimeException: No Usable Database exists or was copied from the assets.
RunExample 2 - Assets 文件被正确命名:-
日志显示:-
10-24 20:43:01.160 8696-8696/? E/SQLiteLog: (14) cannot open file at line 30046 of [9491ba7d73]
10-24 20:43:01.160 8696-8696/? E/SQLiteLog: (14) os_unix.c:30046: (2) open(/data/data/mjt.joblist/databases/JobList) -
10-24 20:43:01.162 8696-8696/? E/SQLiteDatabase: Failed to open database '/data/data/mjt.joblist/databases/JobList'.
android.database.sqlite.SQLiteCantOpenDatabaseException: unknown error (code 14): Could not open database
at android.database.sqlite.SQLiteConnection.nativeOpen(Native Method)
at android.database.sqlite.SQLiteConnection.open(SQLiteConnection.java:209)
at android.database.sqlite.SQLiteConnection.open(SQLiteConnection.java:193)
at android.database.sqlite.SQLiteConnectionPool.openConnectionLocked(SQLiteConnectionPool.java:463)
at android.database.sqlite.SQLiteConnectionPool.open(SQLiteConnectionPool.java:185)
at android.database.sqlite.SQLiteConnectionPool.open(SQLiteConnectionPool.java:177)
at android.database.sqlite.SQLiteDatabase.openInner(SQLiteDatabase.java:806)
at android.database.sqlite.SQLiteDatabase.open(SQLiteDatabase.java:791)
at android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:694)
at android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:669)
at mjt.joblist.CopyDBFromAssets.checkDataBase(CopyDBFromAssets.java:93)
at mjt.joblist.CopyDBFromAssets.createDataBase(CopyDBFromAssets.java:25)
at mjt.joblist.MainActivity.onCreate(MainActivity.java:18)
at android.app.Activity.performCreate(Activity.java:5990)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2278)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387)
at android.app.ActivityThread.access$800(ActivityThread.java:151)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5254)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
10-24 20:43:01.169 8696-8696/? D/CHECKASSET: Asset JobListwas found.
10-24 20:43:01.175 8696-8696/? D/COPYDB: Succesfully copied Database JobList from the assets. Number of bytes copied = 98304 in 6 blocks of length 16384
10-24 20:43:01.204 8696-8696/? D/TESTDB: Found Job Job001
10-24 20:43:01.204 8696-8696/? D/TESTDB: Found Job Job002
10-24 20:43:01.204 8696-8696/? D/TESTDB: Found Job Job003
10-24 20:43:01.204 8696-8696/? D/TESTDB: Found Job Job004
引发了异常(未找到数据库，当检查它是否存在时)，但它没有崩溃，我们看到 职位列表 找到了，98304 字节被复制到 6 个 16k 的 block 中。
然后我们看到数据库中的数据，这是通过 DBHelper 方法获得的。
运行 3 - 后续运行:-
只是 :-
10-24 20:52:34.944 13879-13879/? D/TESTDB: Found Job Job001
10-24 20:52:34.944 13879-13879/? D/TESTDB: Found Job Job002
10-24 20:52:34.944 13879-13879/? D/TESTDB: Found Job Job003
10-24 20:52:34.944 13879-13879/? D/TESTDB: Found Job Job004
关于java - 应用程序崩溃 SQLite DB 处理程序，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/46881241/