blocks|key|126250|text|不幸的是，Realm+Java+API还不支持这一点。您可以在此处https://github.com/realm/realm-java/issues/841按照功能请求进行操作|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|126251|目前的解决办法是在for循环中自己构建查询：|126252|RealmResults<Article>+articles+=+realm.allObjects(Article.class);
RealmQuery+q+=+articles.where();
for+(int+id+:+ids)+{
++++q+=+q.equalTo("id",+id);
}
RealmResults<Article>+filteredArticles+=+q.findAll();|code-block|syntax|javascript|126253|entityMap|0|LINK|mutability|MUTABLE|url|https://github.com/realm/realm-java/issues/841^0|X|1A|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@$A|T|B|U|1|V]]|C|$]]|$1|D|3|E|5|6|7|W|8|@]|9|@]|C|$]]|$1|F|3|G|5|H|7|X|8|@]|9|@]|C|$I|J]]|$1|K|3|-4|5|6|7|Y|8|@]|9|@]|C|$]]]|L|$M|$5|N|O|P|C|$Q|R]]]]

The Realm Java API's doesn't support this yet unfortunately. You can follow the feature request here <a href="https://github.com/realm/realm-java/issues/841" rel="nofollow">https://github.com/realm/realm-java/issues/841</a>

The current work-around would be to build up the query yourself in a for-loop:

<pre><code>RealmResults&lt;Article&gt; articles = realm.allObjects(Article.class);
RealmQuery q = articles.where();
for (int id : ids) {
 q = q.equalTo("id", id);
}
RealmResults&lt;Article&gt; filteredArticles = q.findAll();
</code></pre>

blocks|key|2893378|text|更新：|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|2893379|Realm+1.2.0添加了RealmQuery.in()，用于与多个值进行比较。The+documentation详细说明了所有可用的重载。如果is是Integers，则可以使用This+one方法：|CODE|2893380|public+RealmQuery<E>+in(String+fieldName,+Integer[]+values)|code-block|syntax|javascript|2893381|原始答案：|2893382|如果ids列表为空，@ChristianMelchior的答案将返回所有文章。我希望它返回一个空的RealmResults<Article>。这就是我最终要做的：|2893383|Set<Integer>+articleIds+=+this.getArticleIds();
RealmQuery<Article>+query+=+realm.where(Article.class);
if+(articleIds.size()+==+0)+{
++++//+We+want+to+return+an+empty+list+if+the+list+of+ids+is+empty.+
++++//+Just+use+alwaysFalse
++++query+=+query.alwaysFalse();
}+else+{
++++int+i+=+0;
++++for+(int+id+:+articleIds)+{
++++++++//+The+or()+operator+requires+left+hand+and+right+hand+elements.+
++++++++//+If+articleIds+had+only+one+element+then+it+would+crash+with
++++++++//+"Missing+right-hand+side+of+OR"
++++++++if+(i%2B%2B+>+0)+{
++++++++++++query+=+query.or();
++++++++}
++++++++query+=+query.equalTo("id",+id);
++++}
}
return+query.findAll();|2893384|entityMap|0|LINK|mutability|MUTABLE|url|https://realm.io/docs/java/latest/api/io/realm/RealmQuery.html|1|https://realm.io/docs/java/latest/api/io/realm/RealmQuery.html#in-java.lang.String-java.lang.Integer:A-^0|0|3|0|E|F|24|7|15|H|0|2I|8|1|0|0|0|5|0|1D|L|0|0^^$0|@$1|2|3|4|5|6|7|13|8|@$9|14|A|15|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|16|8|@$9|17|A|18|B|H]|$9|19|A|1A|B|H]]|D|@$9|1B|A|1C|1|1D]|$9|1E|A|1F|1|1G]]|E|$]]|$1|I|3|J|5|K|7|1H|8|@]|D|@]|E|$L|M]]|$1|N|3|O|5|6|7|1I|8|@$9|1J|A|1K|B|C]]|D|@]|E|$]]|$1|P|3|Q|5|6|7|1L|8|@$9|1M|A|1N|B|H]]|D|@]|E|$]]|$1|R|3|S|5|K|7|1O|8|@]|D|@]|E|$L|M]]|$1|T|3|-4|5|6|7|1P|8|@]|D|@]|E|$]]]|U|$V|$5|W|X|Y|E|$Z|10]]|11|$5|W|X|Y|E|$Z|12]]]]

Update:
Realm 1.2.0 has added <code>RealmQuery.in()</code> for a comparison against multiple values. <a href="https://realm.io/docs/java/latest/api/io/realm/RealmQuery.html" rel="nofollow noreferrer">The documentation</a> details all the available overloads. <a href="https://realm.io/docs/java/latest/api/io/realm/RealmQuery.html#in-java.lang.String-java.lang.Integer:A-" rel="nofollow noreferrer">This one</a> is the method we can use if our ids are <code>Integer</code>s:
<pre><code>public RealmQuery&lt;E&gt; in(String fieldName, Integer[] values)
</code></pre>
Original answer:
The answer from @ChristianMelchior returns all articles if the list of ids is empty. I want it to return an empty <code>RealmResults&lt;Article&gt;</code>. That's what I've ended up doing:
<pre><code>Set&lt;Integer&gt; articleIds = this.getArticleIds();
RealmQuery&lt;Article&gt; query = realm.where(Article.class);
if (articleIds.size() == 0) {
 // We want to return an empty list if the list of ids is empty. 
 // Just use alwaysFalse
 query = query.alwaysFalse();
} else {
 int i = 0;
 for (int id : articleIds) {
 // The or() operator requires left hand and right hand elements. 
 // If articleIds had only one element then it would crash with
 // &quot;Missing right-hand side of OR&quot;
 if (i++ &gt; 0) {
 query = query.or();
 }
 query = query.equalTo(&quot;id&quot;, id);
 }
}
return query.findAll();
</code></pre>

blocks|key|123361|text|我偶然发现了这篇文章，我想我可以在这上面投上我的2分钱。尽管我非常欣赏Christian+Melchior和他的答案，但我认为在这种情况下，他的答案是不起作用的(至少在当前版本中)。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|123362|我更喜欢这样做--我个人认为它比Albert+Vila的答案更具可读性：|123363|List<String>+listOfIds+=+[..];
RealmQuery<SomeClass>+query+=+realm.where(SomeClass.class);

boolean+first+=+true;
for+(String+id+:+listOfIds)+{
++++if+(!first)+{
++++++++query.or();
++++}+else+{
++++++++first+=+false;
++++}
++++query.equalTo("id",+id);
}
RealmResults<SomeClass>+results+=+query.findAll();|code-block|syntax|javascript|123364|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|L|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|M|8|@]|9|@]|A|$G|H]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

I just came across this post and I thought I could throw in my 2 cents on this. As much as I appreciate Christian Melchior and his answers I think in this case his answer is not working (at least in the current version).

I prefer to do it like this - I personally think it's more readable than Albert Vila's answer:

<pre><code>List&lt;String&gt; listOfIds = [..];
RealmQuery&lt;SomeClass&gt; query = realm.where(SomeClass.class);

boolean first = true;
for (String id : listOfIds) {
 if (!first) {
 query.or();
 } else {
 first = false;
 }
 query.equalTo("id", id);
}
RealmResults&lt;SomeClass&gt; results = query.findAll();
</code></pre>

blocks|key|124422|text|现在realm+v1.2.0支持对多个值进行比较的RealmQuery.in()。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|124423|entityMap^0|P|F|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|K|8|@]|D|@]|E|$]]]|G|$]]

Now realm v 1.2.0 support <code>RealmQuery.in()</code> for a comparison against multiple values.

blocks|key|2893452|text|从1.2.0开始，Realm就是这样做的：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2893453|public+RealmQuery<E>+in(String+fieldName,+String[]+values)+{
++++if+(values+==+null+%7C%7C+values.length+==+0)+{
++++++++throw+new+IllegalArgumentException(EMPTY_VALUES);
++++}
++++beginGroup().equalTo(fieldName,+values[0]);
++++for+(int+i+=+1;+i+<+values.length;+i%2B%2B)+{
++++++++or().equalTo(fieldName,+values[i]);
++++}
++++return+endGroup();
}|code-block|syntax|javascript|2893454|以前，我就是用this来实现的|offset|length|2893455|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/32066648/realm-query-with-list/32068221#32068221^0|0|0|7|4|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@]|9|@$I|V|J|W|1|X]]|A|$]]|$1|K|3|-4|5|6|7|Y|8|@]|9|@]|A|$]]]|L|$M|$5|N|O|P|A|$Q|R]]]]

This is the way Realm does it since 1.2.0:

<pre><code>public RealmQuery&lt;E&gt; in(String fieldName, String[] values) {
 if (values == null || values.length == 0) {
 throw new IllegalArgumentException(EMPTY_VALUES);
 }
 beginGroup().equalTo(fieldName, values[0]);
 for (int i = 1; i &lt; values.length; i++) {
 or().equalTo(fieldName, values[i]);
 }
 return endGroup();
}
</code></pre>

Previously <a href="https://stackoverflow.com/questions/32066648/realm-query-with-list/32068221#32068221">this</a> is how I did it

I'm building an Android app with the Realm database.

I have a <code>RealmObject</code> subclass called <code>Article</code> which has an <code>id</code> field (it's and <code>int</code> and also a <code>@PrimaryKey</code>). I would like to pass to a query a list of <code>int</code>s (a <code>Set</code>, <code>int[]</code>, or whatever) of article id's and retrieve only those articles.

In SQL would be like this:

<pre><code>SELECT *
FROM `table`
where ID in (5263, 5625, 5628, 5621) 
</code></pre>

I've seen it's possible to do this in iOS in <a href="https://stackoverflow.com/a/27809525/4034572">this StackOverflow question</a>.

How can I do this in Android? Thanks!

Edit: Just to inform, I also asked this on the GitHub repo <a href="https://github.com/realm/realm-java/issues/1757" rel="noreferrer">here</a>.

Realm on Android - How to select multiple objects by list of ids (@PrimaryKey)?

数据库

Android

GitHub

Java

我正在使用Realm数据库构建一个Android应用程序。我有一个名为Article的RealmObject子类，它有一个id字段(它是和int，还有一个@PrimaryKey)。我想将文章id的int( Set、int[]等)列表传递给一个查询，并只检索这些文章。在SQL中是这样的：SELECT *FROM `tab...

问Android上的Realm -如何通过ids列表(@PrimaryKey)选择多个对象？
EN

社区

活动

资源

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问Android上的Realm -如何通过ids列表(@PrimaryKey)选择多个对象？EN

社区

活动

资源

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问Android上的Realm -如何通过ids列表(@PrimaryKey)选择多个对象？
EN