Question

例如这样做有什么好处：

2015-06-01 16:39:35.102+0000 ERROR [o.n.s.CommunityBootstrapper]: Failed to start Neo Server on port [7474]
org.neo4j.server.ServerStartupException: Starting Neo4j Server failed: Component 'org.neo4j.server.database.LifecycleManagingDatabase@6d7232a5' was successfully initialized, but failed to start. Please see attached cause exception.
    at org.neo4j.server.AbstractNeoServer.start(AbstractNeoServer.java:255) ~[neo4j-server-2.2.2.jar:2.2.2]
    at org.neo4j.server.Bootstrapper.start(Bootstrapper.java:117) [neo4j-server-2.2.2.jar:2.2.2]
    at org.neo4j.server.Bootstrapper.main(Bootstrapper.java:69) [neo4j-server-2.2.2.jar:2.2.2]
Caused by: org.neo4j.kernel.lifecycle.LifecycleException: Component 'org.neo4j.server.database.LifecycleManagingDatabase@6d7232a5' was successfully initialized, but failed to start. Please see attached cause exception.
    at org.neo4j.kernel.lifecycle.LifeSupport$LifecycleInstance.start(LifeSupport.java:513) ~[neo4j-kernel-2.2.2.jar:2.2.2]
    at org.neo4j.kernel.lifecycle.LifeSupport.start(LifeSupport.java:115) ~[neo4j-kernel-2.2.2.jar:2.2.2]
    at org.neo4j.server.AbstractNeoServer.start(AbstractNeoServer.java:203) ~[neo4j-server-2.2.2.jar:2.2.2]
    ... 2 common frames omitted
Caused by: java.lang.RuntimeException: Error starting org.neo4j.kernel.EmbeddedGraphDatabase, /data/neo4j
    at org.neo4j.kernel.InternalAbstractGraphDatabase.run(InternalAbstractGraphDatabase.java:334) ~[neo4j-kernel-2.2.2.jar:2.2.2]
    at org.neo4j.kernel.EmbeddedGraphDatabase.<init>(EmbeddedGraphDatabase.java:59) ~[neo4j-kernel-2.2.2.jar:2.2.2]
    at org.neo4j.server.database.LifecycleManagingDatabase$1.newGraphDatabase(LifecycleManagingDatabase.java:44) ~[neo4j-server-2.2.2.jar:2.2.2]
    at org.neo4j.server.database.LifecycleManagingDatabase.start(LifecycleManagingDatabase.java:110) ~[neo4j-server-2.2.2.jar:2.2.2]
    at org.neo4j.kernel.lifecycle.LifeSupport$LifecycleInstance.start(LifeSupport.java:507) ~[neo4j-kernel-2.2.2.jar:2.2.2]
    ... 4 common frames omitted
Caused by: org.neo4j.kernel.lifecycle.LifecycleException: Component 'org.neo4j.kernel.impl.transaction.state.DataSourceManager@7aff1fa3' was successfully initialized, but failed to start. Please see attached cause exception.
    at org.neo4j.kernel.lifecycle.LifeSupport$LifecycleInstance.start(LifeSupport.java:513) ~[neo4j-kernel-2.2.2.jar:2.2.2]
    at org.neo4j.kernel.lifecycle.LifeSupport.start(LifeSupport.java:115) ~[neo4j-kernel-2.2.2.jar:2.2.2]
    at org.neo4j.kernel.InternalAbstractGraphDatabase.run(InternalAbstractGraphDatabase.java:330) ~[neo4j-kernel-2.2.2.jar:2.2.2]
    ... 8 common frames omitted
Caused by: org.neo4j.kernel.lifecycle.LifecycleException: Component 'org.neo4j.kernel.NeoStoreDataSource@5db7419c' was successfully initialized, but failed to start. Please see attached cause exception.
    at org.neo4j.kernel.lifecycle.LifeSupport$LifecycleInstance.start(LifeSupport.java:513) ~[neo4j-kernel-2.2.2.jar:2.2.2]
    at org.neo4j.kernel.lifecycle.LifeSupport.start(LifeSupport.java:115) ~[neo4j-kernel-2.2.2.jar:2.2.2]
    at org.neo4j.kernel.impl.transaction.state.DataSourceManager.start(DataSourceManager.java:117) ~[neo4j-kernel-2.2.2.jar:2.2.2]
    at org.neo4j.kernel.lifecycle.LifeSupport$LifecycleInstance.start(LifeSupport.java:507) ~[neo4j-kernel-2.2.2.jar:2.2.2]
    ... 10 common frames omitted
Caused by: org.neo4j.kernel.impl.storemigration.StoreUpgrader$UpgradingStoreVersionNotFoundException: 'neostore.nodestore.db' does not contain a store version, please ensure that the original database was shut down in a clean state.
    at org.neo4j.kernel.impl.storemigration.UpgradableDatabase.checkUpgradeable(UpgradableDatabase.java:86) ~[neo4j-kernel-2.2.2.jar:2.2.2]
    at org.neo4j.kernel.impl.storemigration.StoreMigrator.needsMigration(StoreMigrator.java:158) ~[neo4j-kernel-2.2.2.jar:2.2.2]
    at org.neo4j.kernel.impl.storemigration.StoreUpgrader.getParticipantsEagerToMigrate(StoreUpgrader.java:259) ~[neo4j-kernel-2.2.2.jar:2.2.2]
    at org.neo4j.kernel.impl.storemigration.StoreUpgrader.migrateIfNeeded(StoreUpgrader.java:134) ~[neo4j-kernel-2.2.2.jar:2.2.2]
    at org.neo4j.kernel.NeoStoreDataSource.upgradeStore(NeoStoreDataSource.java:560) ~[neo4j-kernel-2.2.2.jar:2.2.2]
    at org.neo4j.kernel.NeoStoreDataSource.start(NeoStoreDataSource.java:461) ~[neo4j-kernel-2.2.2.jar:2.2.2]
    at org.neo4j.kernel.lifecycle.LifeSupport$LifecycleInstance.start(LifeSupport.java:507) ~[neo4j-kernel-2.2.2.jar:2.2.2]
    ... 13 common frames omitted

而不是这样做：

class SomeClass
{
    private static final SimpleDateFormat yyyyMMddFormat = new SimpleDateFormat("yyyy-MM-dd"); 
}

Answer 1

在块中，如果初始化不是那么简单，也可以进行一些处理。如果您正在初始化集合，请使用它。

static{
    for(int i = 0; i< 100; i++){
        // new stuff
    }
}

你不能从内联那里做到这一点。

就内联方式而言，如果你不需要额外的处理，它看起来更干净。

在静态块中初始化静态变量的优缺点是什么，而不是内联？

1 个答案: