android - io.realm.exceptions.RealmMigrationNeededException:由于以下错误,需要迁移: - 添加了“SaveMessage”类
问题描述
我正在开发新应用程序,但出现以下异常
java.lang.RuntimeException:无法启动活动 ComponentInfo{com.example.myapplication/com.example.myapplication.MessengerActivity}:io.realm.exceptions.RealmMigrationNeededException:由于以下错误需要迁移:-“SaveMessage”类具有被添加。在 android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3102) 在 android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3237) 在 android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:81) 在 android。 app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135) 在 android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95) 在 android.app.ActivityThread$H.handleMessage(ActivityThread.java: 1929) 在 android.os.Handler.dispatchMessage(Handler.java:106) 在 android.os.Looper.loop(Looper.java:209) 在 android.app.ActivityThread.main(ActivityThread.java:7021) 在 java。在 com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:486) 在 com.android.internal.os.ZygoteInit.main(ZygoteInit.java:872) 的 lang.reflect.Method.invoke(Native Method) ) 原因:io.realm.exceptions.RealmMigrationNeededException:由于以下错误需要迁移: - 添加了“SaveMessage”类。在 io.realm.internal.OsSharedRealm.nativeGetSharedRealm(Native Method) 在 io.realm.internal.OsSharedRealm.(OsSharedRealm.java:171) 在 io.realm.internal.OsSharedRealm.getInstance(OsSharedRealm.java:241) 在 io。领域。
下面是我的代码:
Realm.init(this);
realm = Realm.getDefaultInstance();
realm.beginTransaction();
User userModel = realm.createObject(User.class);
Integer userId = Integer.valueOf("0");
String userName = "Michael";
userModel.setId(userId);
userModel.setName(userName);
//userModel.setIcon("icon");
Integer userId1 = Integer.valueOf("1");
String userName1 = "Lily";
userModel.setId(userId1);
userModel.setName(userName1);
realm.commitTransaction();
RealmResults<User> userModels = realm.where(User.class).findAll();
for (User user : userModels) {
Integer getId = Integer.valueOf(user.getId());
String getName = user.getName();
realm.commitTransaction();
}
SaveMessage saveModel = realm.createObject(SaveMessage.class);
Integer saveId = Integer.valueOf("0");
String savedName = "Michael";
Integer saveIds = Integer.valueOf("1");
String savedNames = "Lily";
saveModel.setmId(saveId);
saveModel.setmUsername(savedName);
saveModel.setmContent("content");
saveModel.ismRightMessage("isRightMessage");
Date now = Calendar.getInstance().getTime();
saveModel.setDate(now);
realm.commitTransaction();
RealmResults<SaveMessage> savesModels = realm.where(SaveMessage.class).findAll();
for (SaveMessage saveMessage : savesModels) {
Integer getId = saveMessage.getId();
String getName = saveMessage.getUsername();
String getContent = saveMessage.getContent();
Date date = saveMessage.getDate();
String rightMessage = String.valueOf(saveMessage.ismRightMessage());
realm.commitTransaction();
}
我的 SaveMessage 模型类:
@RealmClass
public class SaveMessage extends RealmObject {
private int mId;
private String mUsername;
private String mContent;
private Date mCreatedAt;
private boolean mRightMessage;
private String mPictureString;
private String mType;
public SaveMessage(int id, String username, String content, Date createdAt, boolean isRightMessage) {
mId = id;
mUsername = username;
mContent = content;
mCreatedAt = createdAt;
mRightMessage = isRightMessage;
}
public SaveMessage() {
}
public int getId() {
return mId;
}
public String getUsername() {
return mUsername;
}
public String getContent() {
return mContent;
}
public Date getDate() {
return mCreatedAt;
}
public void setDate(Date createdAt) {
mCreatedAt = createdAt;
}
public boolean ismRightMessage() {
return mRightMessage;
}
public int getmId() {
return mId;
}
public void setmId(int mId) {
this.mId = mId;
}
public String getmUsername() {
return mUsername;
}
public void setmUsername(String mUsername) {
this.mUsername = mUsername;
}
public String getmContent() {
return mContent;
}
public void setmContent(String mContent) {
this.mContent = mContent;
}
public boolean ismRightMessage(String isRightMessage) {
return mRightMessage;
}
public void setmRightMessage(boolean mRightMessage) {
this.mRightMessage = mRightMessage;
}
public String getPictureString() {
return mPictureString;
}
public void setPictureString(String pictureString) {
mPictureString = pictureString;
}
public String getType() {
return mType;
}
public void setType(String type) {
mType = type;
}
}
解决方案
您在领域架构中添加了一个新模型,因此您需要迁移您的数据库。你可以这样做:
public class RealmUtility {
private static final int SCHEMA_V_PREV = 1;// previous schema version
private static final int SCHEMA_V_NOW = 2;// change schema version if any change happened in schema
public static int getSchemaVNow() {
return SCHEMA_V_NOW;
}
public static RealmConfiguration getDefaultConfig() {
return new RealmConfiguration.Builder()
.schemaVersion(SCHEMA_V_NOW)
.deleteRealmIfMigrationNeeded()// if migration needed then this methoud will remove the existing database and will create new database
.build();
}
}
如果您不想删除现有数据库并愿意在现有数据库中添加新模型,请这样做:
public class RealmMigrations implements RealmMigration {
@Override
public void migrate(DynamicRealm realm, long oldVersion, long newVersion) {
final RealmSchema schema = realm.getSchema();
if (oldVersion == 1) {
final RealmObjectSchema saveMessage =
schema.get("SaveMessage");
if(saveMessage==null){
saveMessage=realmSchema.create("SaveMessage");}
saveMessage.addField("mId", int.class);
// all field add here similarly
oldVersion++;
}
}
}
public static RealmConfiguration getDefaultConfig() {
return new RealmConfiguration.Builder()
.schemaVersion(SCHEMA_V_NOW)
.migration(new RealmMigrations())
.build();
}
然后像这样初始化领域:
Realm realm = Realm.getInstance(RealmUtility.getDefaultConfig());
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