SQLite資料庫使用

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1、對話方塊的添加

為之前的應用添加對話方塊

需要完成的任務：

1）建立DatePickerFragment

@Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
    
    return new AlertDialog.Builder(getActivity())
            .setView(v)
            .setTitle(R.string.date_picker_title)
            .setPositiveButton(android.R.string.ok,null)
            .create();
}

2）藉助FragmentManager顯示對話方塊

要傳遞crime給DatePickerFragment需要建立一個

newInstance(Date)方法：

public class DatePickerFragment extends DialogFragment {

private static final String ARG_DATE = "date";
private DatePicker mDatePicker;
public static DatePickerFragment newInstance(Date date) {

    Bundle args = new Bundle();
    args.putSerializable(ARG_DATE, date);

    DatePickerFragment fragment = new DatePickerFragment();
    fragment.setArguments(args);
    return fragment;
}

同時在string.xml中添加字串：

<string name="date_picker_title">Date of crime:</string>

對話方塊的響應：

public void onActivityResult(int requestCode, int resultCode, Intent data) {
    if (resultCode != Activity.RESULT_OK) {
        return;
    }

    if (requestCode == REQUEST_DATE) {
        Date date = (Date) data
                .getSerializableExtra(DatePickerFragment.EXTRA_DATE);
        mCrime.setDate(date);
        updateCrime();
        updateDate();
    }

2、工具列及菜單

1）產生表徵圖：

按右鍵drawable目錄，選擇new→Image Asset

 點擊next 進入預覽畫面：

2）響應功能表項目選擇

需在CrimeListFragment中

實現onOptionsItemSelected(MenuItem)方法    

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    switch (item.getItemId()) {
        case R.id.new_crime:
            Crime crime = new Crime();
            CrimeLab.get(getActivity()).addCrime(crime);
            updateUI();
            mCallbacks.onCrimeSelected(crime);
            return true;
        default:
            return super.onOptionsItemSelected(item);
    }
}

在CrimeListFragment中

響應SHOWSUBTITLE功能表項目單擊事件

case R.id.show_subtitle:
    mSubtitleVisible = !mSubtitleVisible;
    getActivity().invalidateOptionsMenu();
    updateSubtitle();
    return true;

3、SQLite資料庫

1）建立初始資料庫

建立CrimeBaseHelper類，代碼如下：  

public class CrimeBaseHelper extends SQLiteOpenHelper {
    private static final int VERSION = 1;
    private static final String DATABASE_NAME = "crimeBase.db";
    public CrimeBaseHelper(Context context) {
        super(context, DATABASE_NAME, null, VERSION);
    }
    @Override
    public void onCreate(SQLiteDatabase db) {
    }
    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    }
}

2)編寫SQL建立初始代碼  

db.execSQL("create table " + CrimeTable.NAME + "(" +
        " _id integer primary key autoincrement, " +
        CrimeTable.Cols.UUID + ", " +
        CrimeTable.Cols.TITLE + ", " +
        CrimeTable.Cols.DATE + ", " +
        CrimeTable.Cols.SOLVED + ", " +
        CrimeTable.Cols.SUSPECT +
        ")"
);

代碼中需要匯入CrimeTable，在CrimeTable一詞上，

按alt+斷行符號，選中提示選項

3）讀取資料庫    

調用query(...)方法查詢記錄

private CrimeCursorWrapper queryCrimes(String whereClause, String[] whereArgs) {
    Cursor cursor = mDatabase.query(
            CrimeTable.NAME,
            null, // Columns - null selects all columns
            whereClause,
            whereArgs,
            null, // groupBy
            null, // having
            null  // orderBy
    );
    return new CrimeCursorWrapper(cursor);
}

 

 

 

 

 

SQLite資料庫使用