我正在尝试将书对象插入数据库中，但是我一直遇到错误。我不知道我在做什么错。我有两节课。代码可以编译，但是当我尝试添加book对象时，它会在MySQLiteHelper类中的addbooks方法上引发错误，但是如果我删除了在ContentValues上插入“ date string”的行，则一切正常，并将book对象添加到数据库中。
AddBook.class
public class AddBooks extends BaseActivity implements View.OnClickListener {
private EditText mBookTitle, mBookAuthor, mBookISBN, mBookDate;
private Button upload;
private MySQLiteHelper db = new MySQLiteHelper(this);
private String title, author, isbn, date;
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.add_books);
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
if (getSupportActionBar() != null)
(getSupportActionBar()).setDisplayHomeAsUpEnabled(true);
}
mBookTitle = findViewById(R.id.book_title_edit);
mBookAuthor = findViewById(R.id.book_author_edit);
mBookISBN = findViewById(R.id.book_isbn_edit);
mBookDate = findViewById(R.id.book_date_edit);
mBookDate.setOnClickListener(this);
upload = findViewById(R.id.book_upload);
upload.setOnClickListener(this);
}
private boolean checkField() {
//get text from the editText fields
boolean valid = true;
View focusView = null;
title = mBookTitle.getText().toString().trim();
author = mBookAuthor.getText().toString().trim();
isbn = mBookISBN.getText().toString().trim();
date = mBookDate.getText().toString();
//gives error report if the editText field is empty
if (TextUtils.isEmpty(title)) {
mBookTitle.setError(getString(R.string.empty_title));
focusView = mBookTitle;
valid = false;
}
if (TextUtils.isEmpty(author)) {
mBookAuthor.setError(getString(R.string.empty_author));
focusView = mBookAuthor;
valid = false;
}
if (!valid) {
focusView.requestFocus();
}
return valid;
}
@Override
public void onClick(View v) {
//dialog popup for date selection on editText click
if (v == mBookDate) {
final Calendar calendar = Calendar.getInstance();
int mYear = calendar.get(Calendar.YEAR);
int mMonth = calendar.get(Calendar.MONTH);
int mDay = calendar.get(Calendar.DAY_OF_MONTH);
DatePickerDialog datePickerDialog = new DatePickerDialog(this,
new DatePickerDialog.OnDateSetListener() {
@Override
public void onDateSet(DatePicker view, int year, int month, int dayOfMonth) {
mBookDate.setText(dayOfMonth + "-" + (month + 1) + "-" + year);
}
}, mYear, mMonth, mDay);
datePickerDialog.show();
}
if (v == upload) {
if (checkField()) {
Book book = new Book(author, title, isbn, date);
//add books to the database
db.addBook(book);
Toast.makeText(this, getString(R.string.success_upload), Toast.LENGTH_SHORT).show();
mBookDate.setText("");
mBookTitle.setText("");
mBookISBN.setText("");
mBookAuthor.setText("");
}
}
}
/**
* Take care of popping the fragment back stack or finishing the activity
* as appropriate.
*/
@Override
public void onBackPressed() {
super.onBackPressed();
}
}
MySQLiteHelper.class
public class MySQLiteHelper extends SQLiteOpenHelper {
// Database Name - BookDB
private static final String DATABASE_NAME = "BookDB";
// Table Name - books and users
private static final String TABLE_BOOKS = "books";
// Columns Names of books Table
private static final String KEY_ID = "id";
private static final String KEY_TITLE = "title";
private static final String KEY_AUTHOR = "author";
private static final String KEY_ISBN = "isbn";
private static final String KEY_DATE_PUB = "date";
// Database Version
private static final int DATABASE_VERSION = 1;
// Log TAG for debugging purpose
private static final String TAG = "SQLiteDebugLog";
// Constructor
public MySQLiteHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
String CREATE_BOOK_TABLE = "CREATE TABLE books ( " + "id INTERGER PRIMARY KEY AUTOINCREMENT, " +
"author TEXT, " + "title TEXT, " + "isbn TEXT, " + "date TEXT)";
// execute an SQL statement to create the table
db.execSQL(CREATE_BOOK_TABLE);
}
// onUpdate() is invoked when you upgrade the database scheme.
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// Drop older books table if existed
db.execSQL("DROP TABLE IF EXISTS books");
this.onCreate(db);
}
//******************************METHODS FOR BOOK*******************************************
public void addBook(Book book){
Log.d(TAG, "addBook() - " + book.toString());
// get reference to writable DB
SQLiteDatabase db = this.getWritableDatabase();
// create ContentValues to add key "column"/value
ContentValues values = new ContentValues();
values.put(KEY_AUTHOR, book.getAuthor()); // get author
values.put(KEY_TITLE, book.getTitle()); // get title
values.put(KEY_ISBN, book.getIsbn()); // get isbn
values.put(KEY_DATE_PUB, book.getDatePublish());
//print the book details
System.out.println("set title: " + book.getTitle());
System.out.println("set author: " + book.getAuthor());
System.out.println("set isbn: "+ book.getIsbn());
System.out.println("set date: " + book.getDatePublish());
// insert
db.insert(TABLE_BOOKS, // table
null, //nullColumnHack
values); // key/value -> keys = column names/ values = column values
// 4. close - release the reference of writable DB
db.close();
}
}
这是我每次尝试添加书时都会不断收到的表簿没有列日期的错误。
D/SQLiteDebugLog: addBook() - com.android.nsuklib.data.Book@1c8cf0f
I/System.out: set title: cool things
set author: Jamse
I/System.out: set isbn: REISUEY
set date: 17-8-2018
E/SQLiteLog: (1) table books has no column named date
E/SQLiteDatabase: Error inserting date=17-8-2018 title=cool things author=Jamse isbn=REISUEY
android.database.sqlite.SQLiteException: table books has no column named date (code 1): , while compiling: INSERT INTO books(date,title,author,isbn) VALUES (?,?,?,?)
at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method)
at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:889)
at android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:500)
at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:588)
at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:58)
at android.database.sqlite.SQLiteStatement.<init>(SQLiteStatement.java:31)
at android.database.sqlite.SQLiteDatabase.insertWithOnConflict(SQLiteDatabase.java:1472)
at android.database.sqlite.SQLiteDatabase.insert(SQLiteDatabase.java:1343)
at com.android.nsuklib.data.MySQLiteHelper.addBook(MySQLiteHelper.java:116)
at com.android.nsuklib.data.AddBooks.onClick(AddBooks.java:99)
at android.view.View.performClick(View.java:6256)
at android.view.View$PerformClick.run(View.java:24697)
at android.os.Handler.handleCallback(Handler.java:789)
at android.os.Handler.dispatchMessage(Handler.java:98)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6541)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)
E/EGL_emulation: tid 10741: eglSurfaceAttrib(1210): error 0x3009 (EGL_BAD_MATCH)
答案 0 :(得分：0)
表格簿没有名为日期的列
因此，请检查表方案或更改列名，也许不允许date作为列名。