android - Realm.io - 如何更新对象？

Question

我使用的是 0.81.1 版本的 Realm。我有这个类:

public class KanjiComp extends RealmObject {

    @PrimaryKey
    private String character;
    private String strokes;
    private int frequency;

    public String getCharacter() {
        return character;
    }

    public void setCharacter(String character) {
        this.character = character;
    }

    public String getStrokes() {
        return strokes;
    }

    public void setStrokes(String strokes) {
        this.strokes = strokes;
    }

    public int getFrequency() {
        return frequency;
    }

    public void setFrequency(int frequency) {
        this.frequency = frequency;
    }
}

我第一次创建这样的对象:

    KanjiComp realmKanjiComp = realm.createObject(KanjiComp.class);
    realmKanjiComp.setCharacter(cur.getString(cur.getColumnIndex("literal")));
    realmKanjiComp.setStrokes(cur.getString(cur.getColumnIndex("strokes")));
    realmKanjiComp.setFrequency(0);

我想增加频率值。为此，我需要可以帮助我更新频率的方法。

Realm 文档是这样说的:

Using primary keys makes it possible to use the createOrUpdate() method, which will look for an existing object with this primary key, an update it if it finds one; if none are found, it will create a new object instead.

但我找不到 createOrUpdate() 方法。使用 JSON 的所有方法。

我的完整代码如下所示:

        try {
            KanjiComp realmKanjiComp = realm.createObject(KanjiComp.class);
            character = cur.getString(cur.getColumnIndex("literal"));
            realmKanjiComp.setCharacter(cur.getString(cur.getColumnIndex("literal")));
            realmKanjiComp.setStrokes(cur.getString(cur.getColumnIndex("strokes")));
            realmKanjiComp.setFrequency(0);
        } catch (Exception e) {
            RealmQuery<KanjiComp> query = realm.where(KanjiComp.class);
            query.equalTo("character", character);
            RealmResults<KanjiComp> rKanjiComp = query.findAll();
            KanjiComp oldKanjiComp = rKanjiComp.get(0);

            KanjiComp realmKanjiComp = realm.update(KanjiComp.class);//update is underlined
            realmKanjiComp.setCharacter(cur.getString(cur.getColumnIndex("literal")));
            realmKanjiComp.setStrokes(cur.getString(cur.getColumnIndex("strokes")));
            realmKanjiComp.setFrequency(oldKanjiComp.getFrequency()+1);
        }

所以我的问题是，如何更新对象的值？有什么方法可以增加我的对象的值(value)吗？

Answer 1

我会选择这样的东西:

void createKanjiCompOrUpdateFrequency() {
    // This query is fast because "character" is an indexed field
    KanjiComp kanjoComp = realm.where(KanjiComp.class)
                               .equalTo("character", someValue)
                               .findFirst();
    realm.beginTransaction();
    if (kanjiComp == null) {
        KanjiComp kanjiComp = realm.createObject(KanjiComp.class);
        // set the fields here
    } else {
        kanjiComp.setFrequency(kanjiComp.getFrequency() + 1);
    }
    realm.commitTransaction();
}