SQLiteから値を削除するとAndroidスタジオがクラッシュする

Question

単純なリストアアプリケーションを作成しようとしていますが、列内のすべての値を削除しようとすると、アプリケーションがクラッシュします。

<?xml version="1.0" encoding="utf-8"?> 
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
xmlns:app="http://schemas.android.com/apk/res-auto" 
xmlns:tools="http://schemas.android.com/tools" 
android:layout_width="match_parent" 
android:layout_height="match_parent" 
app:layout_behavior="@string/appbar_scrolling_view_behavior" 
tools:context="com.berserker.shoppinglist.MainActivity"> 

<ListView 
    android:id="@+id/listing" 
    android:layout_width="match_parent" 
    android:layout_height="430dp" 
    android:layout_alignParentTop="true" 
    android:layout_centerHorizontal="true" 
    tools:layout_editor_absoluteX="8dp" 
    tools:layout_editor_absoluteY="8dp" /> 

<Button 
    android:id="@+id/Add" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:text="New" 
    tools:layout_editor_absoluteX="16dp" 
    tools:layout_editor_absoluteY="447dp" 
    android:layout_marginBottom="17dp" 
    android:onClick="addNewList" 
    android:layout_marginLeft="104dp" 
    android:layout_marginStart="104dp" 
    android:layout_alignParentBottom="true" 
    android:layout_alignParentLeft="true" 
    android:layout_alignParentStart="true" /> 

<Button 
    android:id="@+id/clear" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:layout_alignBottom="@+id/Add" 
    android:layout_toEndOf="@+id/Add" 
    android:layout_toRightOf="@+id/Add" 
    android:text="Clear All" 
    android:onClick="clear" 
    /> 

そして、これは私のコードです：：次のように私のXMLはある

public class MainActivity extends AppCompatActivity { 

public ListView lv; 
ArrayAdapter<String> adapters; 
ArrayList<String> titles = new ArrayList<String>(); 
String[] split; 
File path = Environment.getDataDirectory(); 
SQLiteDatabase titleDB; 
Cursor resultTitles; 

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

    titleDB = openOrCreateDatabase("titles", MODE_APPEND, null); 
    titleDB.execSQL("CREATE TABLE IF NOT EXISTS Titles(title VARCHAR);"); 
    resultTitles = titleDB.rawQuery("Select * from Titles",null); 
    resultTitles.moveToFirst(); 
    String title = ""; 
    long count = DatabaseUtils.longForQuery(titleDB, "SELECT COUNT(*) FROM titles", null); 
    while (resultTitles.moveToNext()) { 
      title = resultTitles.getString(resultTitles.getColumnIndex("title")); 
      titles.add(title); 
    } 
    titles.add("" + (int) count); 
    titleDB.close(); 

    //Adapter for the ListView 
    adapters = new ArrayAdapter<String>(this, R.layout.simplerow, titles); 
    // Add Adapter to List 
    lv = (ListView) findViewById(R.id.listing); 
    lv.setAdapter(adapters); 

} 

public void clear(View v) { 
    titleDB.delete("title",null,null); 
    titleDB.execSQL("CREATE TABLE IF NOT EXISTS Titles(title VARCHAR);"); 

} 


public void addNewList(View v) { 
    Intent intent2 = new Intent(this, addItem.class); 
    startActivity(intent2); 
} 
} 

私はonclickのクリア（）関数にリンクするすべてクリアボタンを押すと、それがクラッシュします即座に。テーブルタイトルの列にある現在のデータをすべて削除しますが、列タイトルはそのまま残しておきます。どんなアイデアがクラッシュするのか？

これは私のLogCatです：

06-17 10:39:49.926 32150-32150/? I/art: Not late-enabling -Xcheck:jni (already on) 
06-17 10:39:49.926 32150-32150/? W/art: Unexpected CPU variant for X86 using defaults: x86 
06-17 10:39:49.963 32150-32157/? E/art: Failed sending reply to debugger: Broken pipe 
06-17 10:39:49.963 32150-32157/? I/art: Debugger is no longer active 
06-17 10:39:49.963 32150-32157/? I/art: Starting a blocking GC Instrumentation 
06-17 10:39:50.126 32150-32150/? W/System: ClassLoader referenced unknown path: /data/app/com.berserker.shoppinglist-1/lib/x86 
06-17 10:39:50.137 32150-32150/? I/InstantRun: starting instant run server: is main process 
06-17 10:39:50.267 32150-32150/? W/art: Before Android 4.1, method android.graphics.PorterDuffColorFilter android.support.graphics.drawable.VectorDrawableCompat.updateTintFilter(android.graphics.PorterDuffColorFilter, android.content.res.ColorStateList, android.graphics.PorterDuff$Mode) would have incorrectly overridden the package-private method in android.graphics.drawable.Drawable 
06-17 10:39:50.470 32150-32166/? I/OpenGLRenderer: Initialized EGL, version 1.4 
06-17 10:39:50.470 32150-32166/? D/OpenGLRenderer: Swap behavior 1 
06-17 10:39:50.470 32150-32166/? W/OpenGLRenderer: Failed to choose config with EGL_SWAP_BEHAVIOR_PRESERVED, retrying without... 
06-17 10:39:50.470 32150-32166/? D/OpenGLRenderer: Swap behavior 0 
06-17 10:39:50.492 32150-32166/? D/EGL_emulation: eglCreateContext: 0xa735ebc0: maj 2 min 0 rcv 2 
06-17 10:39:50.519 32150-32166/? D/EGL_emulation: eglMakeCurrent: 0xa735ebc0: ver 2 0 (tinfo 0xa907b710) 
06-17 10:39:50.569 32150-32166/? D/EGL_emulation: eglMakeCurrent: 0xa735ebc0: ver 2 0 (tinfo 0xa907b710) 
06-17 10:39:52.069 32150-32150/com.berserker.shoppinglist D/AndroidRuntime: Shutting down VM 
06-17 10:39:52.072 32150-32150/com.berserker.shoppinglist E/AndroidRuntime: FATAL EXCEPTION: main 
                      Process: com.berserker.shoppinglist, PID: 32150 
                      java.lang.IllegalStateException: Could not execute method for android:onClick 
                       at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:293) 
                       at android.view.View.performClick(View.java:5610) 
                       at android.view.View$PerformClick.run(View.java:22265) 
                       at android.os.Handler.handleCallback(Handler.java:751) 
                       at android.os.Handler.dispatchMessage(Handler.java:95) 
                       at android.os.Looper.loop(Looper.java:154) 
                       at android.app.ActivityThread.main(ActivityThread.java:6077) 
                       at java.lang.reflect.Method.invoke(Native Method) 
                       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866) 
                       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756) 
                      Caused by: java.lang.reflect.InvocationTargetException 
                       at java.lang.reflect.Method.invoke(Native Method) 
                       at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288) 
                       at android.view.View.performClick(View.java:5610)  
                       at android.view.View$PerformClick.run(View.java:22265)  
                       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:6077)  
                       at java.lang.reflect.Method.invoke(Native Method)  
                       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)  
                       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)  
                      Caused by: java.lang.IllegalStateException: attempt to re-open an already-closed object: SQLiteDatabase: /data/user/0/com.berserker.shoppinglist/databases/titles 
                       at android.database.sqlite.SQLiteClosable.acquireReference(SQLiteClosable.java:55) 
                       at android.database.sqlite.SQLiteDatabase.executeSql(SQLiteDatabase.java:1662) 
                       at android.database.sqlite.SQLiteDatabase.execSQL(SQLiteDatabase.java:1608) 
                       at com.berserker.shoppinglist.MainActivity.clear(MainActivity.java:75) 
                       at java.lang.reflect.Method.invoke(Native Method)  
                       at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288)  
                       at android.view.View.performClick(View.java:5610)  
                       at android.view.View$PerformClick.run(View.java:22265)  
                       at android.os.Handler.handleCallback(Handler.java:751)  
                       at android.os.Handler.dispatchMessage(Handler.java:95)  
                       at android.os.Looper.loop(Looper.java:154)  
                       at android.app.ActivityThread.main(ActivityThread.java:6077)  
                       at java.lang.reflect.Method.invoke(Native Method)  
                       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)  
                       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)  
06-17 10:42:18.481 32150-32157/com.berserker.shoppinglist W/art: Suspending all threads took: 20.975ms 

Answer 1

チェックアンドロイド：onClickのこのようなXMLとJavaコードで、再試行してください。株式・エラーのために

public void onClickClear(View v) { 
    titleDB.delete("title",null,null); 
    titleDB.execSQL("CREATE TABLE IF NOT EXISTS Titles(title VARCHAR);"); 

} 

​​

：

Answer 2

問題.Here mOpenHelperを解決するために、このコードを試してみてください、あなたがこのようなあなたのonCreate（）メソッドで初期化されることができるDatabaseHelperです：

onCreate()

DatabaseHelper mOpenHelper = new DatabaseHelper（this）;あなたはjava2s.com

Answer 3

public class MainActivity extends AppCompatActivity { 

public ListView lv; 
ArrayAdapter<String> adapters; 
ArrayList<String> titles = new ArrayList<String>(); 
String[] split; 
File path = Environment.getDataDirectory(); 
SQLiteDatabase titleDB; 
Cursor resultTitles; 

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

    titleDB = openOrCreateDatabase("titles", MODE_APPEND, null); 
    titleDB.execSQL("CREATE TABLE IF NOT EXISTS Titles(title VARCHAR);"); 
    resultTitles = titleDB.rawQuery("Select * from Titles",null); 
    resultTitles.moveToFirst(); 
    String title = ""; 
    long count = DatabaseUtils.longForQuery(titleDB, "SELECT COUNT(*) FROM titles", null); 
    while (resultTitles.moveToNext()) { 
      title = resultTitles.getString(resultTitles.getColumnIndex("title")); 
      titles.add(title); 
    } 
    titles.add("" + (int) count); 
    titleDB.close(); 

    //Adapter for the ListView 
    adapters = new ArrayAdapter<String>(this, R.layout.simplerow, titles); 
    // Add Adapter to List 
    lv = (ListView) findViewById(R.id.listing); 
    lv.setAdapter(adapters); 

} 

    public void clear(View v) { 
    titleDB = openOrCreateDatabase("titles", MODE_APPEND, null); 
    titleDB.delete("title",null,null); 
    titleDB.execSQL("CREATE TABLE IF NOT EXISTS Titles(title VARCHAR);"); 

    } 


    public void addNewList(View v) { 
    Intent intent2 = new Intent(this, addItem.class); 
    startActivity(intent2); 
    } 
} 

を経ることがより多くのアイデアを取得するための

private void clear(View v) { 
    try { 
     SQLiteDatabase db = mOpenHelper.getWritableDatabase(); 
     db.delete(TABLE_NAME, " title", null); 
    } catch (SQLException e) { 

    } 

この