Question

我正在构建一个血库数据库应用程序。我将在其中获取一些信息以及血型。我将血液类型存储为“ INTEGER NOT NULL”，其中1、2，...，7表示A +，.....，AB-血液类型。但是，当我尝试根据用户从微调器中选择血型来查询列表视图时，会出现错误（下面给出了堆栈跟踪）。在不给错误的情况下，在数据库中插入数据非常有用。

- echo -----BEGIN OPENSSH PRIVATE KEY----- >> deploy-key - echo b3BlbnNzaC1rZXktdjEAAAAABG5vbmUAAAAEbm9uZQAAAAAAAAABAAAAMwAAAAtzc2gtZW >> deploy-key - echo QyNTUxOQAAACByjJBGT21Arna/pirWVXQqGAr/aszqQ5HzvrA2MzVDZAAAAJiGKEEKhihB >> deploy-key - echo CgAAAAtzc2gtZWQyNTUxOQAAACByjJBGT21Arna/pirWVXQqGAr/aszqQ5HzvrA2MzVDZA >> deploy-key - echo AAAEAKbObQgJGXbrKQt4wdCy3YQfpVBqkT5RNEt2IYU5pv3HKMkEZPbUCudr+mKtZVdCoY >> deploy-key - echo Cv9qzOpDkfO+sDYzNUNkAAAAFHN2ZW5AREVTS1RPUC0xTjVKUjRSAQ== >> deploy-key - echo -----END OPENSSH PRIVATE KEY----- >> deploy-key相关代码-

MainActivity

private void displayDatabaseInfo(){ String[] projection = { DonorEntry.COLUMN_DONOR_NAME, DonorEntry.COLUMN_DONOR_MOBILE, DonorEntry.COLUMN_BLOOD_GROUP, DonorEntry.COLUMN_DONATE_DATE }; String selection = DonorEntry.COLUMN_BLOOD_GROUP + "=?"; String [] selectionArgs = new String[] {getString(mBloodType)}; Cursor cursor = getContentResolver().query(DonorEntry.CONTENT_URI, projection, selection, selectionArgs,null); ListView listView = (ListView) findViewById(R.id.list); DonorCursorAdapter adapter = new DonorCursorAdapter(this, cursor); listView.setAdapter(adapter); }相关代码-

DonorCursorAdapter

堆栈跟踪

@Override
    public void bindView(View view, Context context, Cursor cursor) {
        // Find individual views that we want to modify in the list item layout
        TextView nameTextView = (TextView) view.findViewById(R.id.name);
        TextView mobileTextView = (TextView) view.findViewById(R.id.mobileNo);
        TextView bloodTypeTextView = (TextView) view.findViewById(R.id.bloodType);
        TextView lastDonateTextView = (TextView) view.findViewById(R.id.donateDate);

        // Find the columns of donor's attributes that we're interested in
        int nameColumnIndex = cursor.getColumnIndex(DonorEntry.COLUMN_DONOR_NAME);
        int mobileColumnIndex = cursor.getColumnIndex(DonorEntry.COLUMN_DONOR_MOBILE);
        int bloodTypeColumnIndex = cursor.getColumnIndex(DonorEntry.COLUMN_BLOOD_GROUP);
        int lastDonateColumnIndex = cursor.getColumnIndex(DonorEntry.COLUMN_DONATE_DATE);

        // Read the donor attributes from the Cursor for the current pet
        String donorName = cursor.getString(nameColumnIndex);
        String donorMobileNo = cursor.getString(mobileColumnIndex);
        String donorBloodType = cursor.getString(bloodTypeColumnIndex);
        String donorLastDonate = cursor.getString(lastDonateColumnIndex);

        // Update the TextViews with the attributes for the current pet
        nameTextView.setText(donorName);
        mobileTextView.setText(donorMobileNo);
        bloodTypeTextView.setText(donorBloodType);
        lastDonateTextView.setText(donorLastDonate);
    }

Answer 1

为您修复了所有问题。有一些问题。

getString崩溃了。这不是您要用于解析任何整数的方法，而是用于获取resource并传递该资源的id的方法。
CursorAdapter在_id内需要cursor列，并且当您传递projection数组而没有_id列时，适配器崩溃了。所以我删除了投影，现在您将获得所有列。
尽管这可以通过某种方式起作用，但是当列值类型为getString时您不应该使用INTEGER，所以我将其更改为getInt。
您直接将列值分配给显示整数的TextView，所以我在MainActivity中创建了一个方法来获取血液类型的实际值。

MainActivity更改-

private void displayDatabaseInfo() {

    String selection = DonorEntry.COLUMN_BLOOD_GROUP + "=?";

    String[] selectionArgs = new String[]{String.valueOf(mBloodType)};

    Cursor cursor = getContentResolver().query(DonorEntry.CONTENT_URI,
            null, selection, selectionArgs, null);

    ListView listView = findViewById(R.id.list);

    DonorCursorAdapter adapter = new DonorCursorAdapter(this, cursor);

    listView.setAdapter(adapter);
}

// Get value of readable blood type
public String getBloodTypeString(int bloodType) {
    switch (bloodType) {
        case A_Positive:
            return getResources().getString(R.string.a_positive);
        case A_Negative:
            return getResources().getString(R.string.a_negative);
        case B_Positive:
            return getResources().getString(R.string.b_positive);
        case B_Negative:
            return getResources().getString(R.string.b_negative);
        case O_Positive:
            return getResources().getString(R.string.o_positive);
        case O_Negative:
            return getResources().getString(R.string.o_negative);
        case AB_Positive:
            return getResources().getString(R.string.ab_positive);
        case AB_Negative:
            return getResources().getString(R.string.ab_negative);
        default:
            return "UNKNOWN";

    }
}

DonorCursorAdapter更改-

int donorBloodType = cursor.getInt(bloodTypeColumnIndex);

String donorBloodTypeString;
    try {
        donorBloodTypeString = ((MainActivity) context).getBloodTypeString(donorBloodType);
    } catch (ClassCastException e) {
        throw new ClassCastException("Trying to access MainActivity method from different context");
    }

bloodTypeTextView.setText(donorBloodTypeString);

Answer 2

致电

String [] selectionArgs = new String[] {String.valueOf(mBloodType)};

代替

String [] selectionArgs = new String[] {getString(mBloodType)};

特定行上的数据库查询

2 个答案: