更新或从数据库中删除时出错; “无法执行方法”

时间：2012-07-28 16:47:52

标签： android database sqlite

解决方案位于我的帖子底部。

首先，让我为这篇文章的篇幅道歉，但我已经把代码倾注了好几个小时而且我迷失了。我对db方面也非常困惑，因此我的代码重复了一些我能找到的最简单的教程，即使我知道方面已被弃用或者还有其他方法可以减少代码长度。我不确定需要什么，因此下面有大量的代码。

目标：我有一个用户可以填写并保存到数据库表的表单。然后，我将另一个类中的数据显示到ListView（此类在listview上方还有其他功能）。通过单击其中一个列表视图项，将打开另一个与原始表单相同的表单，其中所有信息都已从数据库行填充。此表单有一个保存和删除按钮，可以让您更改某些输入字段（EditText＆＃39; s和Spinner＆＃39; s）并保存以更新行，或选择删除。更新或删除后，活动结束并将您带回listview类。

我不打算添加原始表单数据，因为我知道正确保存。我也知道我的数据正在正确地传输到辅助表单（我可以修改/删除），但是当我尝试更新或删除时，我在logcat中得到以下内容：

07-29 04:18:25.771: E/AndroidRuntime(2116): FATAL EXCEPTION: main
07-29 04:18:25.771: E/AndroidRuntime(2116): java.lang.IllegalStateException: Could not execute method of the activity
07-29 04:18:25.771: E/AndroidRuntime(2116):     at android.view.View$1.onClick(View.java:3591)
07-29 04:18:25.771: E/AndroidRuntime(2116):     at android.view.View.performClick(View.java:4084)
07-29 04:18:25.771: E/AndroidRuntime(2116):     at android.view.View$PerformClick.run(View.java:16966)
07-29 04:18:25.771: E/AndroidRuntime(2116):     at android.os.Handler.handleCallback(Handler.java:615)
07-29 04:18:25.771: E/AndroidRuntime(2116):     at android.os.Handler.dispatchMessage(Handler.java:92)
07-29 04:18:25.771: E/AndroidRuntime(2116):     at android.os.Looper.loop(Looper.java:137)
07-29 04:18:25.771: E/AndroidRuntime(2116):     at android.app.ActivityThread.main(ActivityThread.java:4745)
07-29 04:18:25.771: E/AndroidRuntime(2116):     at java.lang.reflect.Method.invokeNative(Native Method)
07-29 04:18:25.771: E/AndroidRuntime(2116):     at java.lang.reflect.Method.invoke(Method.java:511)
07-29 04:18:25.771: E/AndroidRuntime(2116):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
07-29 04:18:25.771: E/AndroidRuntime(2116):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
07-29 04:18:25.771: E/AndroidRuntime(2116):     at dalvik.system.NativeStart.main(Native Method)
07-29 04:18:25.771: E/AndroidRuntime(2116): Caused by: java.lang.reflect.InvocationTargetException
07-29 04:18:25.771: E/AndroidRuntime(2116):     at java.lang.reflect.Method.invokeNative(Native Method)
07-29 04:18:25.771: E/AndroidRuntime(2116):     at java.lang.reflect.Method.invoke(Method.java:511)
07-29 04:18:25.771: E/AndroidRuntime(2116):     at android.view.View$1.onClick(View.java:3586)
07-29 04:18:25.771: E/AndroidRuntime(2116):     ... 11 more
07-29 04:18:25.771: E/AndroidRuntime(2116): Caused by: java.lang.NullPointerException
07-29 04:18:25.771: E/AndroidRuntime(2116):     at com.rone.glucometer.AddDBHelper.updateDetails(AddDBHelper.java:119)
07-29 04:18:25.771: E/AndroidRuntime(2116):     at com.rone.glucometer.UpdateDBDetails.clickUpdateDelete(UpdateDBDetails.java:420)
07-29 04:18:25.771: E/AndroidRuntime(2116):     ... 14 more

我的AddDBHelper类如下所示：

public class AddDBHelper {

public static final String KEY_ROWID ="_id";
public static final String KEY_CATEG = "Category";
public static final String KEY_CATEGPOS = "Category_Pos";
public static final String KEY_BGL = "BGL";
public static final String KEY_CARBS = "Carbs";
public static final String DB_NAME = "Glucometer.db";
public static final String DB_TABLE = "Journal";
private static final int DB_VERSION = 1;

private DbHelper myDBHelper;
private final Context mContext;
private SQLiteDatabase glucoDB;

private static class DbHelper extends SQLiteOpenHelper {

    public DbHelper(Context context) {
        super(context, DB_NAME, null, DB_VERSION);
    }


    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL("CREATE TABLE " + DB_TABLE + " (" +
            KEY_ROWID + " INTEGER PRIMARY KEY AUTOINCREMENT, " +
            KEY_CATEG + " TEXT NOT NULL, " +
            KEY_CATEGPOS + " TEXT NOT NULL, " +
            KEY_BGL + " TEXT NOT NULL, " +
            KEY_CARBS + " TEXT NOT NULL);"

);}
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL("DROP TABLE IF EXISTS " + DB_TABLE);
        onCreate(db);
    }

}


public AddDBHelper(Context c) {
    mContext = c;
}

public AddDBHelper open() throws SQLException {
    myDBHelper = new DbHelper(mContext);
    glucoDB = myDBHelper.getWritableDatabase();
    return this;
}

public void close() {
    myDBHelper.close();
}

public long createEntry(String Category, String CategoryPos, String BGL, String Carbs) {
    ContentValues cv = new ContentValues();
    cv.put(KEY_CATEG, Category);
    cv.put(KEY_CATEGPOS, CategoryPos);
    cv.put(KEY_BGL, BGL);
    cv.put(KEY_CARBS, Carbs);
return glucoDB.insert(DB_TABLE, null, cv); }

public Cursor getEntries() {        
    return glucoDB.query(DB_TABLE, new String[] {
            KEY_ROWID,
            KEY_CATEG,
            KEY_CATEGPOS,
            KEY_BGL,
            KEY_CARBS}, null, null, null, null, null); }

public void updateDetails(DBDetails dbdetails) {
    SQLiteDatabase db = myDBHelper.getWritableDatabase();

    ContentValues cv = new ContentValues();
    cv.put(AddDBHelper.KEY_ROWID, UpdateDBDetails.newRow);
    cv.put(AddDBHelper.KEY_CATEG, UpdateDBDetails.newCateg);
    cv.put(AddDBHelper.KEY_CATEGPOS, UpdateDBDetails.newCategPos);
    cv.put(AddDBHelper.KEY_BGL, UpdateDBDetails.newBGL);
    cv.put(AddDBHelper.KEY_CARBS, UpdateDBDetails.newCarbs);

    db.update(DB_TABLE, cv, KEY_ROWID + "=?", new String[] {String.valueOf(UpdateDBDetails.newRow)});
}


public void deleteDetails(DBDetails dbdetails) {
    SQLiteDatabase db = myDBHelper.getWritableDatabase();
    db.delete(DB_TABLE, KEY_ROWID +"=?", 
            new String[] {String.valueOf(UpdateDBDetails.newRow)});
    db.close();
}}

我的ListView活动如下：

public class FuncLogbook extends DashMenuActivity implements OnItemClickListener {

private ListView list_LogbookResults;
private ListAdapter list_LogbookAdap;
private ArrayList<DBDetails> LogbookArrayList;

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

    list_LogbookResults = (ListView) findViewById(R.id.list_logbookResults);
    list_LogbookResults.setOnItemClickListener(this);

    LogbookArrayList = new ArrayList<DBDetails>();
    list_LogbookAdap = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, populateList());
    list_LogbookResults.setAdapter(list_LogbookAdap); }

@SuppressWarnings("deprecation")
public List<String> populateList() {
    List<String> BGLResultsList = new ArrayList<String>();

    AddDBHelper logbook = new AddDBHelper(this);
    logbook.open();
    Cursor cur = logbook.getEntries();
    startManagingCursor(cur);

    while (cur.moveToNext()) {
        String RowID = cur.getString(0);
        String Category = cur.getString(1);
        String CategoryPos = cur.getString(2);
        String BGL = cur.getString(3);
        String Carbs = cur.getString(4);


        DBDetails detailsClass = new DBDetails();
        detailsClass.setuCateg(Category);
        detailsClass.setuCategPos(CategoryPos);
        detailsClass.setuBGL(BGL);
        detailsClass.setuCarbs(Carbs);


        LogbookArrayList.add(detailsClass);
        BGLResultsList.add("BGL: " + BGL + "\nRow ID: " + RowID);
    }

    return BGLResultsList;
}

@Override
protected void onResume() {
    super.onResume();
    LogbookArrayList = new ArrayList<DBDetails>();
    list_LogbookAdap = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, populateList());
    list_LogbookResults.setAdapter(list_LogbookAdap);
}

@Override
protected void onStart() {
    super.onStart();
    LogbookArrayList = new ArrayList<DBDetails>();
    list_LogbookAdap = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, populateList());
    list_LogbookResults.setAdapter(list_LogbookAdap);
}

public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3) {      
    Intent UpdateDBDetails = new Intent(this, UpdateDBDetails.class);

    DBDetails clickedObject = LogbookArrayList.get(arg2);
    Bundle dataBundle =  new Bundle();
    dataBundle.putString("clickeduCateg", clickedObject.getuCateg());
    dataBundle.putString("clickeduCategPos", clickedObject.getuCategPos());
    dataBundle.putString("clickeduBGL", clickedObject.getuBGL());
    dataBundle.putString("clickeduCarbs", clickedObject.getuCarbs());


    UpdateDBDetails.putExtras(dataBundle);
    startActivity(UpdateDBDetails);
}}

数据被收集到我的DBDetails类：

public class DBDetails {

private String uCateg;
private String uCategPos;
private String uBGL;
private String uCarbs;

public String getuCateg() {
    return uCateg;
}

public void setuCateg(String uCateg) {
    this.uCateg = uCateg;
}

public String getuCategPos() {
    return uCategPos;
}

public void setuCategPos(String uCategPos) {
    this.uCategPos = uCategPos;
}

public String getuBGL() {
    return uBGL;
}

public void setuBGL(String uBGL) {
    this.uBGL = uBGL;
}

public String getuCarbs() {
    return uCarbs;
}

public void setuCarbs(String uCarbs) {
    this.uCarbs = uCarbs;
}

最后，我的表单显示数据：

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

update_category_spinner = (Spinner) findViewById(R.id.update_category_spinner);
    ArrayAdapter<CharSequence> category_adapter = ArrayAdapter.createFromResource(
            this, R.array.category_array, android.R.layout.simple_spinner_item);

    category_adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    update_category_spinner.setAdapter(category_adapter);

    update_category_spinner.setOnItemSelectedListener(new OnItemSelectedListener() {
        public void onItemSelected(AdapterView<?> arg0, View arg1, int arg2, long arg3) {
            newCat = update_category_spinner.getSelectedItem().toString();
            newCatPos = (update_category_spinner.getSelectedItemPosition() + " Position");
        }

        public void onNothingSelected(AdapterView<?> arg0) {

        }
    });

Bundle takeBundledData = getIntent().getExtras();

    bundleduRowId = takeBundledData.getString("clickeduRowId");
    bundleduCateg = takeBundledData.getString("clickeduCateg");
    bundleduCategPos = takeBundledData.getString("clickeduCategPos");
    bundleduBGL = takeBundledData.getString("clickeduBGL");
    bundleduCarbs = takeBundledData.getString("clickeduCarbs");

CategoryPosition = String.valueOf(bundleduCategPos.charAt(0));
    update_category_spinner.setSelection(Integer.parseInt(CategoryPosition), true);
update_edit_bgl.setText(bundleduBGL);
    update_edit_carbs.setText(bundleduCarbs); }

public static double round(double unrounded, int precision, int roundingMode) {
    BigDecimal bd = new BigDecimal(unrounded);
    BigDecimal rounded = bd.setScale(precision, roundingMode);
    return rounded.doubleValue();
}


public void checkNewBGL() {
    String checkBGL = update_edit_bgl.getText().toString();
    if (checkBGL.matches("")) {
        NewBGLValid = "";
    } else {
        float BGLUnRound = Float.parseFloat(update_edit_bgl.getText().toString());
         double BGLRound= round(BGLUnRound, 1, BigDecimal.ROUND_HALF_UP);
         NewBGLValid = String.valueOf(BGLRound);
    }
    return;
    }

    public void checkNewCarbs() {
    String checkCarbs = update_edit_carbs.getText().toString();
    if (checkCarbs.matches("")) {
        NewCarbsValid = "0";
    } else {        
        NewCarbsValid = update_edit_carbs.getText().toString();
    }
    return;
    }

public void clickUpdateDelete(View v) {

    checkNewBGL();
    checkNewCarbs();

    newCateg = newCat;
    newCategPos = newCatPos;
    newBGL = NewBGLValid;
    newCarbs = NewCarbsValid;

DBDetails dbdetails = new DBDetails();

    dbdetails.setuCateg(newCateg);
    dbdetails.setuCategPos(newCategPos);
    dbdetails.setuBGL(newBGL);
    dbdetails.setuCarbs(newCarbs);

if (v.getId() == R.id.update_button_delete) {
        AddDBHelper deleteEntry = new AddDBHelper(this);
        deleteEntry.deleteDetails(dbdetails);
    } else if (v.getId() == R.id.update_button_save) {
        AddDBHelper updateEntry = new AddDBHelper(this);
        updateEntry.updateDetails(dbdetails);
    }   
}}

我更新到了

public void updateDetails(DBDetails dbdetails) { 
SQLiteDatabase db = myDBHelper.getWritableDatabase();
ContentValues cv = new ContentValues();
cv.put(AddDBHelper.KEY_CATEG, UpdateDBDetails.newCateg); 
cv.put(AddDBHelper.KEY_CATEGPOS, UpdateDBDetails.newCategPos); 
cv.put(AddDBHelper.KEY_BGL, UpdateDBDetails.newBGL);
cv.put(AddDBHelper.KEY_CARBS, UpdateDBDetails.newCarbs);
db.update(DB_TABLE, cv, KEY_ROWID + "=?", new String[] {UpdateDBDetails.getRowId});}

并添加到UpdateDBDetails：

getRowId = dbdetails.getuRow();

虽然同样的问题正在发生。此外，在这个阶段，我没有关闭我的光标，因为如果我点击了＆＃39;返回＆＃39;按钮而不是保存或删除，它由于尝试查询已经关闭的游标而崩溃;我想我以后会解决这个问题。你是对的，我确实忘了定义UpdateDBDetails，但是我已经将DBDetails上下文传递给了方法，所以我现在改为

public void updateDetails(DBDetails dbdetails) {
SQLiteDatabase db = myDBHelper.getWritableDatabase(); 
ContentValues cv = new ContentValues(); 
cv.put(AddDBHelper.KEY_CATEG, dbdetails.getuCateg()); 
cv.put(AddDBHelper.KEY_CATEGPOS, dbdetails.getuCategPos()); 
cv.put(AddDBHelper.KEY_BGL, dbdetails.getuBGL()); 
cv.put(AddDBHelper.KEY_CARBS, dbdetails.getuCarbs()); 
db.update(DB_TABLE, cv, KEY_ROWID + "=?", new String[] {dbdetails.getuRow()}); }

但同样的问题。

解决方案：

我的DBDetails.java添加了以下行：

 public String getuRow() {
    return uRow;
}

public void setuRow(String uRow) {
    this.uRow = uRow;
}

我的Listview（FuncLogbook.Java）添加了以下行\ changed：

public List<String> populateList() {
    List<String> BGLResultsList = new ArrayList<String>();

    AddDBHelper logbook = new AddDBHelper(this);
    logbook.open();
    Cursor cur = logbook.getEntries();
    startManagingCursor(cur);

    while (cur.moveToNext()) {
        String RowID = cur.getString(0);
        String Category = cur.getString(3);
        String CategoryPos = cur.getString(4);
        String BGL = cur.getString(5);
        String Carbs = cur.getString(6);

DBDetails detailsClass = new DBDetails();
        detailsClass.setuRow(RowID);
        detailsClass.setuCateg(Category);
        detailsClass.setuCategPos(CategoryPos);
        detailsClass.setuBGL(BGL);
        detailsClass.setuCarbs(Carbs);
LogbookArrayList.add(detailsClass);
}
return BGLResultsList; }

public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3) {      
    Intent UpdateDBDetails = new Intent(this, UpdateDBDetails.class);

    DBDetails clickedObject = LogbookArrayList.get(arg2);
    Bundle dataBundle =  new Bundle();
    dataBundle.putString("clickeduRowId", clickedObject.getuRow());
    dataBundle.putString("clickeduCateg", clickedObject.getuCateg());
    dataBundle.putString("clickeduCategPos", clickedObject.getuCategPos());
    dataBundle.putString("clickeduBGL", clickedObject.getuBGL());
    dataBundle.putString("clickeduCarbs", clickedObject.getuCarbs());
        UpdateDBDetails.putExtras(dataBundle);
    startActivity(UpdateDBDetails);
}

MY DB帮助程序类（AddDBHelper.java）显示以下内容：

public void updateDetails(DBDetails dbdetails) {

    ContentValues cv = new ContentValues();
    cv.put(AddDBHelper.KEY_CATEG, dbdetails.getuCateg());
    cv.put(AddDBHelper.KEY_CATEGPOS, dbdetails.getuCategPos());
    cv.put(AddDBHelper.KEY_BGL, dbdetails.getuBGL());
    cv.put(AddDBHelper.KEY_CARBS, dbdetails.getuCarbs());
int count = glucoDB.update(DB_TABLE, cv, KEY_ROWID + "=?", new String[] {String.valueOf(dbdetails.getuRow())});
    Log.v("AddDbHelper", "Row " + dbdetails.getuRow() + " updated? " + count);
}

public void deleteDetails(DBDetails dbdetails) {

    int count = glucoDB.delete(DB_TABLE, KEY_ROWID +"=?", 
            new String[] {String.valueOf(dbdetails.getuRow())});
    Log.v("AddDbHelper", "Row " + dbdetails.getuRow() + " deleted? " + count);
}

最后，我的UpdateDBDetails.java（包含要修改或删除的信息的表单）显示：

onCreate...{
Bundle takeBundledData = getIntent().getExtras();

    bundleduRowId = takeBundledData.getString("clickeduRowId");
    bundleduCateg = takeBundledData.getString("clickeduCateg");
    bundleduCategPos = takeBundledData.getString("clickeduCategPos");
    bundleduBGL = takeBundledData.getString("clickeduBGL");
    bundleduCarbs = takeBundledData.getString("clickeduCarbs");
}

public void clickUpdateDelete(View v) {


    checkNewBGL();
    checkNewCarbs();

    newCateg = newCat;
    newCategPos = newCatPos;
    newBGL = NewBGLValid;
    newCarbs = NewCarbsValid;

AddDBHelper modifyEntry = new AddDBHelper(this);
    modifyEntry.open();

    DBDetails dbdetails = new DBDetails();

    dbdetails.setuRow(bundleduRowId);

    if (v.getId() == R.id.update_button_delete) {
        modifyEntry.deleteDetails(dbdetails);
    } else if (v.getId() == R.id.update_button_save) {
        dbdetails.setuCateg(newCateg);
        dbdetails.setuCategPos(newCategPos);
        dbdetails.setuBGL(newBGL);
        dbdetails.setuCarbs(newCarbs);
modifyEntry.updateDetails(dbdetails);
    }   
    modifyEntry.close();
    finish();
}

1 个答案:

答案 0 :(得分：1)

我看不到你在哪里定义UpdateDBDetails。但我对SQLiteDatabase.update（）提出了一些建议。

首先将行ID添加到UpdateDBDetails对象并提供get方法。

然后使用这样的更新方法：

public void updateDetails() {
    ContentValues cv = new ContentValues();
    cv.put(AddDBHelper.KEY_CATEG, UpdateDBDetails.newCateg);
    cv.put(AddDBHelper.KEY_CATEGPOS, UpdateDBDetails.newCategPos);
    cv.put(AddDBHelper.KEY_BGL, UpdateDBDetails.newBGL);
    cv.put(AddDBHelper.KEY_CARBS, UpdateDBDetails.newCarbs);

    db.update(DB_TABLE, cv, KEY_ROWID + "=?", new String[] {UpdateDBDetails.getuRow()});
}

更新行时，其ID不应更改，否则您将创建新行或更新其他行...因此，ContentValues对象不应尝试添加有关AddDBHelper.KEY_ROWID的任何内容，而应添加SQLiteDatabase .update（）的WHERE子句应该具有当前行的ID。希望这是有道理的。

只要您使用new AddDBHelper或myDBHelper.getWritableDatabase()（或直接使用光标），就应该在完成后关闭这些对象。否则，它们会一直存在，不必要地消耗内存。

从LogCat添加

我看到你的LogCat，我猜测UpdateDBDetails有问题但我刚刚注意到你调用updateDetails（）的地方并推荐：

将行ID添加到DBDetails，以便您可以这样做：

AddDBHelper helper = new AddDBHelper(this);
helper.open();

DBDetails dbdetails = new DBDetails();
dbdetails.setuRow(bundleduRowId);

if (v.getId() == R.id.update_button_delete) {
    helper.deleteDetails(dbdetails);
} else if (v.getId() == R.id.update_button_save) {
    dbdetails.setuCateg(newCateg);
    dbdetails.setuCategPos(newCategPos);
    dbdetails.setuBGL(newBGL);
    dbdetails.setuCarbs(newCarbs);
    helper.updateDetails(dbdetails);
}   

helper.close();

最后一次AddDbHepler：

public void updateDetails(DBDetails dbdetails) {
    ContentValues cv = new ContentValues();
    cv.put(AddDBHelper.KEY_CATEG, dbdetails.newCateg);
    cv.put(AddDBHelper.KEY_CATEGPOS, dbdetails.newCategPos);
    cv.put(AddDBHelper.KEY_BGL, dbdetails.newBGL);
    cv.put(AddDBHelper.KEY_CARBS, dbdetails.newCarbs);

    glucoDB.update(DB_TABLE, cv, KEY_ROWID + "=?", new String[] {String.valueOf(dbdetails.getuRow())});
}

<强> logcat的

更新和删除都返回一个影响了多少行的整数，你可以这样看到它们：

int count = glucoDB.update(DB_TABLE, cv, KEY_ROWID + "=?", new String[] {String.valueOf(dbdetails.getuRow())});
Log.v("AddDbHelper", "Row " + dbdetails.getuRow() + " updated? " + count);

如果您看到“...已更新？1”，那么它可以正常工作，否则存储在DBDetails中的ID将会关闭。

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