Java 从SQLite中删除值会导致应用程序Android Studio崩溃

我正在尝试制作一个简单的列表应用程序，但当我尝试删除列中的所有值时，该应用程序崩溃。我的XML如下所示：

<?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"
    />

---

检查android:onClick在xml和java代码中，如下图所示，然后重试。

无法为android执行方法：onClick

---

对于共享错误：

请尝试以下代码来解决您的问题。这里的mOpenHelper是DatabaseHelper，您可以在onCreate（）方法中对其进行如下初始化：

onCreate（）

DatabaseHelper mOpenHelper=新的DatabaseHelper（此）

要获得更多想法，您可以通过

公共类main活动扩展appcompat活动{
公共列表视图lv；
阵列适配器；
ArrayList titles=新的ArrayList（）；
字符串[]拆分；
文件路径=Environment.getDataDirectory（）；
sqlitedatabasetitledb；
光标结果；
@凌驾
创建时受保护的void（Bundle savedInstanceState）{
super.onCreate（savedInstanceState）；
setContentView（R.layout.activity_main）；
titleDB=openOrCreateDatabase（“titles”，模式_-APPEND，null）；
titleDB.execSQL（“如果不存在，则创建表Titles（title VARCHAR）；”；
resultitles=titleDB.rawQuery（“从标题中选择*项”，null）；
resultitles.moveToFirst（）；
字符串标题=”；
long count=DatabaseUtils.longForQuery（titleDB，“从标题中选择计数（*），null）；
while（resultitles.moveToNext（））{
title=resultitles.getString（resultitles.getColumnIndex（“title”）；
标题。添加（标题）；
}
标题。添加（“+（整数）计数）；
标题b.close（）；
//ListView的适配器
适配器=新的阵列适配器（此，R.layout.simplerow，标题）；
//将适配器添加到列表
lv=（ListView）findViewById（R.id.listing）；
低压设置适配器（适配器）；
}
公共空间清理（视图五）{
titleDB=openOrCreateDatabase（“titles”，模式_-APPEND，null）；
标题b.删除（“标题”，空，空）；
titleDB.execSQL（“如果不存在，则创建表Titles（title VARCHAR）；”；
}
公共void addNewList（视图五）{
Intent intent2=新的Intent（此，addItem.class）；
星触觉（intent2）；
}
}

---

尝试此操作

发布崩溃日志如何获取崩溃日志？单击android Studiot底部的绿色android图标以下是我的日志猫：请发布创建数据库实例的openOrCreateDatabase方法IT仍然崩溃：/请共享您的日志猫。我已在上面发布了日志猫

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);
}
}

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

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

}

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

    }

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);
   }
}