Question

有谁能告诉我这个logcat要求的是什么？现在我试图在SQlite android中创建，读取，更新，删除字符串数据，但是我得到了一些NumberFormatException，如何解决这个问题？

建议谢谢你宝贵的时间！..

logcat的

05-09 11:53:21.660: E/AndroidRuntime(854): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.sqlite_sample/com.example.sqlite_sample.MainActivity}: java.lang.NumberFormatException: unable to parse 'null' as integer
05-09 11:53:21.660: E/AndroidRuntime(854):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647)
05-09 11:53:21.660: E/AndroidRuntime(854):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
05-09 11:53:21.660: E/AndroidRuntime(854):  at android.app.ActivityThread.access$1500(ActivityThread.java:117)
05-09 11:53:21.660: E/AndroidRuntime(854):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
05-09 11:53:21.660: E/AndroidRuntime(854):  at android.os.Handler.dispatchMessage(Handler.java:99)
05-09 11:53:21.660: E/AndroidRuntime(854):  at android.os.Looper.loop(Looper.java:123)
05-09 11:53:21.660: E/AndroidRuntime(854):  at android.app.ActivityThread.main(ActivityThread.java:3683)
05-09 11:53:21.660: E/AndroidRuntime(854):  at java.lang.reflect.Method.invokeNative(Native Method)
05-09 11:53:21.660: E/AndroidRuntime(854):  at java.lang.reflect.Method.invoke(Method.java:507)
05-09 11:53:21.660: E/AndroidRuntime(854):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
05-09 11:53:21.660: E/AndroidRuntime(854):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
05-09 11:53:21.660: E/AndroidRuntime(854):  at dalvik.system.NativeStart.main(Native Method)
05-09 11:53:21.660: E/AndroidRuntime(854): Caused by: java.lang.NumberFormatException: unable to parse 'null' as integer
05-09 11:53:21.660: E/AndroidRuntime(854):  at java.lang.Integer.parseInt(Integer.java:356)
05-09 11:53:21.660: E/AndroidRuntime(854):  at java.lang.Integer.parseInt(Integer.java:332)
05-09 11:53:21.660: E/AndroidRuntime(854):  at com.example.sqlite_sample.DatabaseHandler.getAllContacts(DatabaseHandler.java:98)
05-09 11:53:21.660: E/AndroidRuntime(854):  at com.example.sqlite_sample.MainActivity.onCreate(MainActivity.java:40)
05-09 11:53:21.660: E/AndroidRuntime(854):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
05-09 11:53:21.660: E/AndroidRuntime(854):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
05-09 11:53:21.660: E/AndroidRuntime(854):  ... 11 more

MainActivity.java

public class MainActivity extends Activity 
{

String str_value = "Contact 1";

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    DatabaseHandler db = new DatabaseHandler(this);

    // Inserting Contacts
    Log.d("Insert: ", "Inserting ..");
    db.addContact(new Contact(str_value));
    db.addContact(new Contact("Contact 2"));
    db.addContact(new Contact("Contact 3"));

    // Reading all contacts
    Log.d(">>--Reading: ", "Reading all contacts..");
    List<Contact> contacts = db.getAllContacts();       

    for (Contact cn : contacts) {
        String log = "Id: "+cn.getID()+" ,Name: " + cn.getName() ;

    // Writing Contacts to log
    Log.d("Name: ", log);

    }
 }}

Contact.java

public class Contact {

//private variables
int _id;
String _name;

// Empty constructor
public Contact(){

}
// constructor
public Contact(int id, String name){
    this._id = id;
    this._name = name;
}

// constructor
public Contact(String name){
    this._name = name;
}
// getting ID
public int getID(){
    return this._id;
}

// setting id
public void setID(int id){
    this._id = id;
}

// getting name
public String getName(){
    return this._name;
}

// setting name
public void setName(String name){
    this._name = name;
}}

DadabaseHandler.java

public class DatabaseHandler extends SQLiteOpenHelper
{

// All Static variables
// Database Version
private static final int DATABASE_VERSION = 1;

// Database Name
private static final String DATABASE_NAME = "contactsManager";

// Contacts table name
private static final String TABLE_CONTACTS = "contacts";

// Contacts Table Columns names
private static final String KEY_ID = "id";
private static final String KEY_NAME = "name";

public DatabaseHandler(Context context) {
    super(context, DATABASE_NAME, null, DATABASE_VERSION);
}

// Creating Tables
@Override
public void onCreate(SQLiteDatabase db) {
    String CREATE_CONTACTS_TABLE = "CREATE TABLE " + TABLE_CONTACTS + "("
            + KEY_ID + " INTEGER PRIMARY KEY," + KEY_NAME + " TEXT,"+ ")";
    db.execSQL(CREATE_CONTACTS_TABLE);
}

// Upgrading database
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    // Drop older table if existed
    db.execSQL("DROP TABLE IF EXISTS " + TABLE_CONTACTS);

    // Create tables again
    onCreate(db);
}

// Adding new contact
void addContact(Contact contact) {
    SQLiteDatabase db = this.getWritableDatabase();

    ContentValues values = new ContentValues();
    values.put(KEY_NAME, contact.getName()); // Contact Name

    // Inserting Row
    db.insert(TABLE_CONTACTS, null, values);
    db.close(); // Closing database connection
}

// Getting single contact
Contact getContact(int id) {
    SQLiteDatabase db = this.getReadableDatabase();

    Cursor cursor = db.query(TABLE_CONTACTS, new String[] { KEY_ID,
            KEY_NAME }, KEY_ID + "=?",
            new String[] { String.valueOf(id) }, null, null, null);
    if (cursor != null)
        cursor.moveToFirst();

    Contact contact = new Contact(Integer.parseInt(cursor.getString(0)),
            cursor.getString(1));
    // return contact
    return contact;
}

// Getting All Contacts
public List<Contact> getAllContacts() {
    List<Contact> contactList = new ArrayList<Contact>();
    // Select All Query
    String selectQuery = "SELECT  * FROM " + TABLE_CONTACTS;

    SQLiteDatabase db = this.getWritableDatabase();
    Cursor cursor = db.rawQuery(selectQuery, null);

    // looping through all rows and adding to list
    if (cursor.moveToFirst()) {
        do {
            Contact contact = new Contact();
            contact.setID(Integer.parseInt(cursor.getString(0)));
            contact.setName(cursor.getString(1));
            // Adding contact to list
            contactList.add(contact);
        } while (cursor.moveToNext());
    }

    return contactList;
}

// Updating single contact
public int updateContact(Contact contact) {
    SQLiteDatabase db = this.getWritableDatabase();

    ContentValues values = new ContentValues();
    values.put(KEY_NAME, contact.getName());

    // updating row
    return db.update(TABLE_CONTACTS, values, KEY_ID + " = ?",
            new String[] { String.valueOf(contact.getID()) });
}

// Deleting single contact
public void deleteContact(Contact contact) {
    SQLiteDatabase db = this.getWritableDatabase();
    db.delete(TABLE_CONTACTS, KEY_ID + " = ?",
            new String[] { String.valueOf(contact.getID()) });
    db.close();
}

// Getting contacts Count
public int getContactsCount() {
    String countQuery = "SELECT  * FROM " + TABLE_CONTACTS;
    SQLiteDatabase db = this.getReadableDatabase();
    Cursor cursor = db.rawQuery(countQuery, null);
    cursor.close();

    // return count
    return cursor.getCount();
}}

Answer 1

试试这个

 contact.setID(cursor.getInt(0));

而不是

 contact.setID(Integer.parseInt(cursor.getString(0)));

在您的getContact(int id)和getAllContacts()方法

中你也错了吗

+ KEY_ID + " INTEGER PRIMARY KEY," + KEY_NAME + " TEXT,"+ ")"; // remove , after TEXT

更正您的SQL创建表格命令，如

String CREATE_CONTACTS_TABLE = "CREATE TABLE " + TABLE_CONTACTS + "("
        + KEY_ID + " INTEGER PRIMARY KEY," + KEY_NAME + " TEXT"+ ")";

在android中使用sqlite时出现NumberFormatException

1 个答案: