Question

我知道这个问题并不新鲜，但我在这里找到的所有其他例子都没有用。这就是为什么我写信给你。

我创建了一个图书应用程序，您可以在其中保存来自googlebooks的bookdata，并可以将数据保存到sqlite数据库中。 bookdata将显示在列表视图中。如果单击一行，该行的所有数据将显示在另一个活动的EdittExts中 - 看起来像详细的书籍视图。一些示例图片：Listview; detailed bookview

现在我想让用户可以编辑这些bookinfos。我实现了一些代码来更新和删除信息，我从Logcat获取信息，创建了Db，但是当我返回ListView时，没有更新或删除数据。

我在youtube上使用了一个名为“Android Studio Tutorial - 37 - Update Database”的视频转换为我的解决方案

也许你可以帮助我。

按照我的书信息代码：

protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_book_info);
        bookDBHelper = new BookDBHelper(this);
        Typeface myTypeface = Typeface.createFromAsset(getAssets(), "Lobster.ttf");
        TextView myTextView = (TextView) findViewById(R.id.yourbookinfo);
        myTextView.setTypeface(myTypeface);

        btn_update = (Button) findViewById(R.id.button_update);

        Intent intent = getIntent();

        String secret_title = intent.getStringExtra(BookDataListActivity.EXTRA_MSG1);
        Secret_editText_title = (EditText) findViewById(R.id.secret_edittext_title);
        Secret_editText_title.setText(secret_title);

        String book_title = intent.getStringExtra(BookDataListActivity.EXTRA_MSG1);
        passedbooktitle = (EditText) findViewById(R.id.passed_booktitle);
        passedbooktitle.setText(book_title);

        String book_author = intent.getStringExtra(BookDataListActivity.EXTRA_MSG2);
        passedbookauthor = (EditText) findViewById(R.id.passed_bookauthor);
        passedbookauthor.setText(book_author);

        String book_date = intent.getStringExtra(BookDataListActivity.EXTRA_MSG3);
        passedbookdate = (EditText) findViewById(R.id.passed_bookdate);
        passedbookdate.setText(book_date);

        String book_rating = intent.getStringExtra(BookDataListActivity.EXTRA_MSG4);
        passedbookrating = (EditText) findViewById(R.id.passed_bookrating);
        passedbookrating.setText(book_rating);

        String book_shelf = intent.getStringExtra(BookDataListActivity.EXTRA_MSG5);
        passedbookshelf = (EditText) findViewById(R.id.passed_bookshelf);
        passedbookshelf.setText(book_shelf);

    }


    public void updateBookInfo(View view){
        bookDBHelper = new BookDBHelper(getApplicationContext());
        sqLiteDatabaseBooks = bookDBHelper.getWritableDatabase();

        secret_editText_titel = Secret_editText_title.getText().toString();

        String booktitle, bookauthor, bookdate, bookrating, bookshelf;
        booktitle = passedbooktitle.getText().toString();
        bookauthor = passedbookauthor.getText().toString();
        bookdate = passedbookdate.getText().toString();
        bookrating = passedbookrating.getText().toString();
        bookshelf = passedbookshelf.getText().toString();
        int count = bookDBHelper.updateEditedBookInfo(secret_editText_titel,
                booktitle,bookauthor, bookdate, bookrating, bookshelf, sqLiteDatabaseBooks);
        Toast.makeText(getApplicationContext(), count+" book updated", Toast.LENGTH_LONG).show();
        finish();

    }

    public void deleteBook(View view){
        bookDBHelper = new BookDBHelper(getApplicationContext());
        sqLiteDatabaseBooks = bookDBHelper.getWritableDatabase();
        bookDBHelper.deleteBookInformation(secret_editText_titel, sqLiteDatabaseBooks);
        Toast.makeText(getBaseContext(), "Book deleted", Toast.LENGTH_LONG).show();
    }

对于我的BookDBHelper：

public int updateEditedBookInfo(String old_title, String new_title, String new_author,
                                     String new_date, String new_rating,
                                     String new_shelf, SQLiteDatabase sqLiteDatabase){
        ContentValues contentValues = new ContentValues();
        contentValues.put(BookContent.NewBookInfo.BOOK_TITLE, new_title);
        contentValues.put(BookContent.NewBookInfo.BOOK_AUTHOR, new_author);
        contentValues.put(BookContent.NewBookInfo.BOOK_DATE, new_date);
        contentValues.put(BookContent.NewBookInfo.BOOK_RATING, new_rating);
        contentValues.put(BookContent.NewBookInfo.BOOK_SHELF, new_shelf);

        String selection = BookContent.NewBookInfo.BOOK_TITLE + " = ?";
        String [] selection_args = {old_title};
        int count =  sqLiteDatabase.update(BookContent.NewBookInfo.TABLE_NAME_BOOKS, contentValues, selection, selection_args);
        return count;
    }

    public void deleteBookInformation(String book_title,SQLiteDatabase sqLiteDatabase){
    String selection = BookContent.NewBookInfo.BOOK_TITLE+ "  =?";
    String [] selection_args = {book_title};
    sqLiteDatabase.delete(BookContent.NewBookInfo.TABLE_NAME_BOOKS, selection, selection_args);
}

按要求编辑activity_book_info.XML

<?xml version="1.0" encoding="utf-8"?>
    <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.kasutwentyseven.gui4selfshelf.Books.BookInfoActivity"
    android:background="@color/Background">

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/yourbookinfo"
        android:id="@+id/yourbookinfo"
        android:textSize="25dp"
        android:textColor="@color/Textcolor"
        android:gravity="center_horizontal"
        android:textStyle="bold"
        />

    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/yourbookinfo"
        android:layout_alignParentStart="true"
        android:id="@+id/linearLayout5">

        <LinearLayout
            android:orientation="horizontal"
            android:layout_width="match_parent"
            android:layout_height="wrap_content">

            <ImageView
                android:layout_width="100dp"
                android:layout_height="match_parent"
                android:id="@+id/passed_bookimage" />

            <LinearLayout
                android:orientation="vertical"
                android:layout_width="match_parent"
                android:layout_height="match_parent">

                <EditText
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:id="@+id/passed_booktitle" />

                <EditText
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:id="@+id/passed_bookauthor" />

                <EditText
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:id="@+id/passed_bookdate" />

                <EditText
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:id="@+id/passed_bookrating" />

                <EditText
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:id="@+id/passed_bookshelf" />
            </LinearLayout>
        </LinearLayout>
    </LinearLayout>

    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/linearLayout5"
        android:layout_alignParentStart="true"
        android:id="@+id/linearLayout6">

        <Button
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/btn_update"
            android:id="@+id/button_update"
            android:onClick="updateBookInfo"/>

        <Button
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/btn_delete"
            android:id="@+id/btn_delete_book"
            android:onClick="deleteBook"/>
    </LinearLayout>

    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/linearLayout6">

        <EditText
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/secret_edittext_title" />
    </LinearLayout>
</RelativeLayout>

Answer 1

在@ 0x0nosugar的帮助下（谢谢）我找到了解决方案：

到updatebookinfo：我补充说：

Intent intent = new Intent(getApplicationContext(), BookDataListActivity.class);
startActivity(intent);

并删除：

    public void DeleteData(){
    btn_delete_book.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Integer deletedRows = bookDBHelper.deleteDate(passedbooktitle.getText().toString());
            if (deletedRows > 0) {
                Toast.makeText(getApplicationContext(), " Book deleted", Toast.LENGTH_LONG).show();
                Intent intent = new Intent(getApplicationContext(), BookDataListActivity.class);
                startActivity(intent);
                finish();
            } else {
                Toast.makeText(getApplicationContext(), " Book not deleted", Toast.LENGTH_LONG).show();
            }
        }

    });

在BookDBHelper：

    public Integer deleteDate (String book_title){
    SQLiteDatabase sqLiteDatabase = this.getWritableDatabase();
    String selection = BookContent.NewBookInfo.BOOK_TITLE+ " = ?";
    String[] selection_args = {book_title};
    return sqLiteDatabase.delete(BookContent.NewBookInfo.TABLE_NAME_BOOKS,selection, selection_args);
}

活动列表中的

方法：

    @Override
public void onResume(){
    super.onResume();
    bookListDataAdapter.notifyDataSetChanged();

}

更新和删除listview中的行

1 个答案: