android - 从android中的 Realm 删除单个对象数据/行

Question

我像这样添加了单个用户的数据:

Realm realm = Realm.getDefaultInstance();
newUser = new UserDatabase();

realm.executeTransaction(new Realm.Transaction() {

  public void execute(Realm realm) {
     newUser.setClassName(classSectionName);
     newUser.setClassNO(classNO);
     newUser.setImageUrl(imageUrl);
     newUser.setRollNo(rollNO);
     newUser.setSchool(school);              

  // and now saved the data in peresistant data like this:
  realm.copyToRealm(newUser);
  }
});

但是我找不到从 Realm 数据库中删除单个条目的方法，即使我这样尝试过，它也不起作用。

Realm realm = Realm.getDefaultInstance();
UserDatabase tempUser = new UserDatabase();
final RealmResults<UserDatabase> students = realm.where(UserDatabase.class).findAll();

  for(int i=0 ;  i<students.size();i++){
     final int index =i;
     if((students.get(i).getUserID()).equals(prefs.getString(QRActivity.USER_ID_AFTER_LOGIN,"jpt"))&&
     (students.get(i).getUserName()).equals(prefs.getString(QRActivity.USER_NAME_AFTER_LOGIN,"jpt"))){

        realm.executeTransaction(new Realm.Transaction() {

            public void execute(Realm realm) {

             //Trying to delete a row from realm.                                   

             students.deleteFromRealm(index);

             }
            });

    }
 }

有人知道吗？

Answer 1

您总能找到匹配的 instance来自 RealmResults<UserDatabase>使用 Realm Query而不是为它运行循环。试试这个。

final RealmResults<UserDatabase> students = realm
    .where(UserDatabase.class)
    .findAll();

UserDatabase userdatabase = students
    .where()
    .equalTo("userId",prefs.getString(QRActivity.USER_ID_AFTER_LOGIN,"jpt"))
    .equalTo("userName",prefs.getString(QRActivity.USER_NAME_AFTER_LOGIN,"jpt"))
    .findFirst();

if(userdatabase!=null) {

    if (!realm.isInTransaction()) {
        realm.beginTransaction();
    }

    userdatabase.deleteFromRealm();

    realm.commitTransaction();
}

注意: 我只是假定您的列为“userId”和“userName”，您可以改写您的列名。