Question

我是Realm Android的新用户，目前我需要在我的项目中使用Realm，但我经常遇到这个Cannot migrate a Realm file that is already open错误，这种情况经常在我打开应用程序时发生。

FATAL EXCEPTION: main
Process: com.etobee.driver, PID: 31866
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.etobee.driver/com.etobee.driver.activity.HomeActivity}: java.lang.IllegalStateException: Cannot migrate a Realm file that is already open: /data/data/com.etobee.driver/files/default6
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2460)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2522)
    at android.app.ActivityThread.access$800(ActivityThread.java:169)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1421)
    at android.os.Handler.dispatchMessage(Handler.java:111)
    at android.os.Looper.loop(Looper.java:194)
    at android.app.ActivityThread.main(ActivityThread.java:5546)
    at java.lang.reflect.Method.invoke(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:372)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:967)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:762)
Caused by: java.lang.IllegalStateException: Cannot migrate a Realm file that is already open: /data/data/com.etobee.driver/files/default6
    at io.realm.BaseRealm$3.onResult(BaseRealm.java:740)
    at io.realm.RealmCache.invokeWithGlobalRefCount(RealmCache.java:274)
    at io.realm.BaseRealm.migrateRealm(BaseRealm.java:735)
    at io.realm.Realm.migrateRealm(Realm.java:1361)
    at com.etobee.driver.util.RealMHelper.init(RealMHelper.java:35)
    at com.etobee.driver.activity.DefaultActivity.onCreate(DefaultActivity.java:138)
    at com.etobee.driver.activity.HomeActivity.onCreate(HomeActivity.java:91)
    at android.app.Activity.performCreate(Activity.java:5975)
    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1111)
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2413)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2522) 
    at android.app.ActivityThread.access$800(ActivityThread.java:169) 
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1421) 
    at android.os.Handler.dispatchMessage(Handler.java:111) 
    at android.os.Looper.loop(Looper.java:194) 
    at android.app.ActivityThread.main(ActivityThread.java:5546) 
    at java.lang.reflect.Method.invoke(Native Method) 
    at java.lang.reflect.Method.invoke(Method.java:372)

以下是我初始化Realm的方法，我在主要活动中将其称为onCreate。

public static void init(Context context){
    // Create a RealmConfiguration that saves the Realm file in the app's "files" directory.
    RealmConfiguration config0 = new RealmConfiguration.Builder(context)
            .name("default6")
            .schemaVersion(7)
            .build();
    try {
        Realm.migrateRealm(config0, new RealmMigration() {    /**--- ERROR HERE **/
            @Override
            public void migrate(DynamicRealm realm, long oldVersion, long newVersion) {
                // DynamicRealm exposes an editable schema
                RealmSchema schema = realm.getSchema();
            }
        });
    } catch (FileNotFoundException ignored) {
        // If the Realm file doesn't exist, just ignore.
    }
    Realm.setDefaultConfiguration(config0);
}

事情是它并不总是发生，它是随机发生的，但经常发生。我已经搜索过这个问题，但还没有找到。请帮忙。

提前谢谢。

Answer 1

static RealmConfiguration realmConfiguration = null;

public static void init(Context context){
    if(realmConfiguration == null) {
        // Create a RealmConfiguration that saves the Realm file in the app's "files" directory.
        realmConfiguration = new RealmConfiguration.Builder(context.getApplicationContext())
            .name("default6")
            .schemaVersion(7)
            .migration(new MyMigration())
            .build();
        Realm.setDefaultConfiguration(realmConfiguration);
    }
}

和

 public class MyMigration implements RealmMigration {
      @Override
      public void migrate(DynamicRealm realm, long oldVersion, long newVersion) {
          // DynamicRealm exposes an editable schema
          RealmSchema schema = realm.getSchema();
          // Loop through each version when an upgrade occurs.
          for (long version = oldVersion + 1; version <= newVersion; version++) {
              switch (version) {
                  case 1:
                     // migrate to version 1
                     break;
                  case 2:
                     // migrate to version 2
                     break;          
                  //...
                  case 7:
                     // migrate to version 7
                     break;
              }
          }
      }

      @Override
      public int hashCode() {
           return MyMigration.class.hashCode();
      }

      @Override
      public boolean equals(Object obj) {
           return obj != null && obj instanceof MyMigration;
      }
 }

无法迁移已经打开的Realm文件~Ereal~Android

1 个答案: