Java SQLite通过单击“更新表中的某些列”；加上「；按钮错误和崩溃

假设我的应用程序让用户输入金额，然后单击“添加”按钮将交易添加到“交易”表中，用户输入的金额也将更新“支出”表中指定类别（特定列/字段）的金额

添加按钮的代码如下所示：

public void AddTransactions (final int temp_position) {
        button_add.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                int temp_id = 0;

                Cursor transactionlatestid = myDb.getLatestTransactionID(temp_position);
                if (transactionlatestid.getCount() == 0) {
                    temp_id = 1;
                } else {
                    transactionlatestid.moveToFirst();
                    temp_id = transactionlatestid.getInt(0);
                    temp_id += 1;
                }

                String transaction_id = String.valueOf(temp_id);

                String flightposition_id = String.valueOf(temp_position);

                boolean isInserted = myDb.insertTransactionData(amount.getText().toString(), category, note.getText().toString(), transaction_id, flightposition_id);


                if (isInserted = true) {
                    Toast.makeText(AddExpenses.this, "Transaction Inserted !", Toast.LENGTH_LONG).show();
                    clearText();
                    temp += 1;
                    getLatestAmount(temp_position, category);
                }
                else {
                    Toast.makeText(AddExpenses.this, "Transaction not Inserted !", Toast.LENGTH_LONG).show();
                }


            }
        });
    }

public void getLatestAmount (int temp_position, String category) {
        temp_position += 1;
        String id = String.valueOf(temp_position);
        String temp_category = "";
        double amountfromdb = 5.00 ;

        if (category == "Food and Drinks")
        {
            temp_category = "foodndrinks";
        }
        else if (category == "Travel")
        {
            temp_category = "travel";
        }
        else if (category == "Shopping")
        {
            temp_category = "shopping";
        }
        else if (category == "Entertainment")
        {
            temp_category = "entertainment";
        }
        else if (category == "Others")
        {
            temp_category = "others";
        }

        Cursor latestamount = myDb.getLatestAmount(id, temp_category);
        if (latestamount.getCount() == 0) {
            Toast.makeText(AddExpenses.this, "No amount found !", Toast.LENGTH_LONG).show();
        } else {
            latestamount.moveToFirst();
            amountfromdb = latestamount.getDouble(0);
            updateAddTotalExpenses(id ,temp_category, amountfromdb);
        }
    }

成功添加事务时调用方法“getLatestAmount”。此方法用于获取“支出”表中当前已存在的指定类别的金额。例如，如果类别为“食品和饮料”，则此方法将从“spendings”表返回该列“FoodAndDrinks”中的值，然后调用“updateAddTotalExpenses”

代码如下：

public void AddTransactions (final int temp_position) {
        button_add.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                int temp_id = 0;

                Cursor transactionlatestid = myDb.getLatestTransactionID(temp_position);
                if (transactionlatestid.getCount() == 0) {
                    temp_id = 1;
                } else {
                    transactionlatestid.moveToFirst();
                    temp_id = transactionlatestid.getInt(0);
                    temp_id += 1;
                }

                String transaction_id = String.valueOf(temp_id);

                String flightposition_id = String.valueOf(temp_position);

                boolean isInserted = myDb.insertTransactionData(amount.getText().toString(), category, note.getText().toString(), transaction_id, flightposition_id);


                if (isInserted = true) {
                    Toast.makeText(AddExpenses.this, "Transaction Inserted !", Toast.LENGTH_LONG).show();
                    clearText();
                    temp += 1;
                    getLatestAmount(temp_position, category);
                }
                else {
                    Toast.makeText(AddExpenses.this, "Transaction not Inserted !", Toast.LENGTH_LONG).show();
                }


            }
        });
    }

public void getLatestAmount (int temp_position, String category) {
        temp_position += 1;
        String id = String.valueOf(temp_position);
        String temp_category = "";
        double amountfromdb = 5.00 ;

        if (category == "Food and Drinks")
        {
            temp_category = "foodndrinks";
        }
        else if (category == "Travel")
        {
            temp_category = "travel";
        }
        else if (category == "Shopping")
        {
            temp_category = "shopping";
        }
        else if (category == "Entertainment")
        {
            temp_category = "entertainment";
        }
        else if (category == "Others")
        {
            temp_category = "others";
        }

        Cursor latestamount = myDb.getLatestAmount(id, temp_category);
        if (latestamount.getCount() == 0) {
            Toast.makeText(AddExpenses.this, "No amount found !", Toast.LENGTH_LONG).show();
        } else {
            latestamount.moveToFirst();
            amountfromdb = latestamount.getDouble(0);
            updateAddTotalExpenses(id ,temp_category, amountfromdb);
        }
    }

此方法“updateAddTotalExpenses”用于将指定类别的“支出”表中的金额与用户输入的金额之和相加，然后将最新金额更新到“支出”表中指定的“类别”中

my DatabaseHelper.class中扩展SQLiteOpenHelper的“支出”表代码：-

    private static final String SPENDING_TABLE = "spendings";
    private static final String ID_SPENDING = "id";
    private static final String BUDGET = "budget";
    private static final String TOTAL_EXPENSES = "total_expenses";
    private static final String FOODNDRINKS = "foodndrinks";
    private static final String TRAVEL = "travel";
    private static final String SHOPPING = "shopping";
    private static final String ENTERTAINMENT = "entertainment";
    private static final String OTHERS = "others";
    private static final String BALANCE = "balance";

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL("CREATE TABLE " + SPENDING_TABLE + " (ID INTEGER PRIMARY KEY AUTOINCREMENT, BUDGET DOUBLE, TOTAL_EXPENSES DOUBLE, FOODNDRINKS DOUBLE, TRAVEL DOUBLE, SHOPPING DOUBLE, ENTERTAINMENT DOUBLE, OTHERS DOUBLE, BALANCE DOUBLE)");

        db.execSQL("CREATE TABLE " + TRANSACTION_TABLE + "(ID INTEGER PRIMARY KEY AUTOINCREMENT, AMOUNT DOUBLE NOT NULL, CATEGORY TEXT NOT NULL, NOTE TEXT, TRANSACTION_ID TEXT NOT NULL, FLIGHT_ID INTEGER NOT NULL, FOREIGN KEY (FLIGHT_ID) REFERENCES FLIGHT_TABLE(id) )");
    }

下面的方法位于DatabaseHelper.class中，该类从主类调用，以获取“spendings”表中指定类别的数量

“updateFnDData”下面的方法位于DatabaseHelper.class中，该类从主类调用，以使用newestamount（旧金额+用户输入的新金额）更新指定类别的金额

***注意：现在我只有一个方法来更新“spendings”表中的一列，即“FoodDrinks”列，因为我只想在添加更多之前测试我的概念和代码是否正确

    public boolean updateFnDData(String id, String category, double newamount) {
        SQLiteDatabase db = this.getWritableDatabase();

        ContentValues contentValues = new ContentValues();

        db.update(SPENDING_TABLE, contentValues, "id = ?"+"category = ?", new String[] {id});

        return true;

    }

下面是当我在

编辑文本

框中输入金额后尝试单击“添加”按钮时出现的日志猫，交易已成功添加到“交易”表中，但指定类别的“支出”表中的金额未更新。特别是这两种方法

getLatestAmount
数据库助手.class
中的
和
“updateFnDData”

   --------- beginning of crash
10-23 22:07:23.419 4070-4070/project.myapplication E/AndroidRuntime: FATAL EXCEPTION: main
    Process: project.myapplication, PID: 4070
    java.lang.NumberFormatException: empty String
        at sun.misc.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:1842)
        at sun.misc.FloatingDecimal.parseDouble(FloatingDecimal.java:110)
        at java.lang.Double.parseDouble(Double.java:539)
        at project.myapplication.AddExpenses.updateAddTotalExpenses(AddExpenses.java:231)
        at project.myapplication.AddExpenses.getLatestAmount(AddExpenses.java:225)
        at project.myapplication.AddExpenses$3.onClick(AddExpenses.java:155)
        at android.view.View.performClick(View.java:6294)
        at android.view.View$PerformClick.run(View.java:24770)
        at android.os.Handler.handleCallback(Handler.java:790)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:164)
        at android.app.ActivityThread.main(ActivityThread.java:6494)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)

在
updateFnDData（）
的这些行中：

ContentValues contentValues = new ContentValues();
db.update(SPENDING_TABLE, contentValues, "id = ?"+"category = ?", new String[] {id});

将空的
contentValues
传递给
update（）
方法


在
db.update（）之前
设置
contentValues
如下：

contentValues.put（columnname，newamount）

将
columnname
替换为要更新的列的名称

编辑在需要更新的支出表中，没有
类别
列。也许您应该将
update（）
方法的
WHERE
部分更改为类似于：
“id=？AND something=？”


Edit2在
updateFnDData（）
中对此进行更改：

添加您的建议！但我的应用程序仍然崩溃，logcat显示的“错误”代码与我在问题中发布的完全相同！：（参见我编辑过的答案。
“id=？”+“category=？”
“我明白你的意思！但是当我的“spendings”表中没有列“category”时，我之所以选择“category=？”是因为我希望这个更新方法能够更新“Food and Drinks”、“Travel”、“Shopping”和etc列，而不必为我要更新的每个列创建更新方法。“category”变量应该表示列名。因此，如果我将“category”变量中的“foodndweads”传递到update（）方法中，我希望该方法更新“foodndweads”如果你明白我的意思，你知道我应该修改什么吗？我从那条语句中删除了+“category=？”，但仍然是相同的错误：（我发现了错误，因为“clearText（）”在调用另一个方法之前！非常感谢！
ContentValues contentValues = new ContentValues();
contentValues.put("foodndrinks", newamount);
db.update(SPENDING_TABLE, contentValues, "id = ?", new String[] {id});