java - 如何从具有不同结果的领域数据库中查询java
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how to query from realm database with distinct results java
提问by Mucahit
I have got a Realmobject class, and storing lots of data in there, imagine that I have a String uid;field. I want to get uid names, but on same uid names just only one time,
For example
我有一个Realm对象类，并在其中存储了大量数据，想象一下我有一个 String uid;字段。我想获得 uid 名称，但只有一次在相同的 uid 名称上，例如
uid
用户界面
AA
机管局
AA
机管局
BB
BB
CC
抄送
DD
DD
BB
BB
BB
BB
I want to get just AA,
我只想得到 AA，
BB,
BB，
CC,
抄送，
DD.
DD。
Only one time. I looked over realm documentation but couldn't find anything.
只有一次。我查看了领域文档，但找不到任何内容。
Thanks for answers.
感谢您的回答。
回答by Isaac Kingston
UPDATED :
更新 ：
You can use distinct() to get distinct entries for an object class.
您可以使用 distinct() 获取对象类的不同条目。
// Returns the set of users that all have a different name
RealmResults<User> users = realm.where(User.class).distinct("name");
Note: .distinct will only work on fields that are indexed (@Index or @PrimaryKey). It doesn't work with child object property.
注意： .distinct 仅适用于已编入索引的字段（@Index 或 @PrimaryKey）。它不适用于子对象属性。
You can find more information about this method here in the official documentation. https://realm.io/docs/java/latest/api/io/realm/Realm.html#distinct-java.lang.Class-java.lang.String-][1]
您可以在官方文档中找到有关此方法的更多信息。 https://realm.io/docs/java/latest/api/io/realm/Realm.html#distinct-java.lang.Class-java.lang.String-][1]
回答by Amol Suryawanshi
Please use below steps to work distinct on Realm
请使用以下步骤在 Realm 上进行不同的工作
Update your realm version to realm :1.2.0 . because in older version distinct not working properly.
将您的领域版本更新为 realm :1.2.0 。因为在旧版本中不同的不能正常工作。
add @Index property to variable on which you want to apply distinct
将 @Index 属性添加到要对其应用不同的变量
execute your query like this
像这样执行您的查询
RealmResult<Example> realmReault =realm.where(Example.class).distinct("uid");
to include realm dependency in your project you can add below line in build.gradle(Project)
要在您的项目中包含领域依赖项，您可以在 build.gradle(Project) 中添加以下行
buildscript {
repositories {
jcenter()
}
dependencies {
classpath 'com.android.tools.build:gradle:2.2.1'
classpath "io.realm:realm-gradle-plugin:1.2.0"
// NOTE: Do not place your application dependencies here; they belong
// in the individual module build.gradle files
}
}
Above code is tested and working properly
上面的代码已经过测试并且可以正常工作
