我的AVD是API 15,我不知道为什么,但每当我在模拟器上运行应用程序时,以下消息都会出现.除了控制台中的错误消息之外,它似乎没有造成任何问题.
[2012-06-17 00:03:26 - ddmlib] Broken pipe
java.io.IOException: Broken pipe
at sun.nio.ch.FileDispatcher.write0(Native Method)
at sun.nio.ch.SocketDispatcher.write(SocketDispatcher.java:47)
at sun.nio.ch.IOUtil.writeFromNativeBuffer(IOUtil.java:122)
at sun.nio.ch.IOUtil.write(IOUtil.java:93)
at sun.nio.ch.SocketChannelImpl.write(SocketChannelImpl.java:352)
at com.android.ddmlib.JdwpPacket.writeAndConsume(JdwpPacket.java:213)
at com.android.ddmlib.Client.sendAndConsume(Client.java:575)
at com.android.ddmlib.HandleHeap.sendREAQ(HandleHeap.java:348)
at com.android.ddmlib.Client.requestAllocationStatus(Client.java:421)
at com.android.ddmlib.DeviceMonitor.createClient(DeviceMonitor.java:837)
at com.android.ddmlib.DeviceMonitor.openClient(DeviceMonitor.java:805)
at com.android.ddmlib.DeviceMonitor.processIncomingJdwpData(DeviceMonitor.java:765)
at com.android.ddmlib.DeviceMonitor.deviceClientMonitorLoop(DeviceMonitor.java:652)
at com.android.ddmlib.DeviceMonitor.access$100(DeviceMonitor.java:44)
at com.android.ddmlib.DeviceMonitor$3.run(DeviceMonitor.java:580)
可能是什么原因？
我正在研究99个Haskell问题,并找到了一个解决方案,用于查找列表的最后一个元素:
myLast = foldr1 (const id)
类型const就是a -> b -> a但的const id是b -> a -> a
有啥这里的魔力？
刚刚在Haskell的排序算法中弄湿了我的脚.我已经实现了insert-sort和merge-sort
insert_sort :: (Ord a, Show a) => [a] -> [a]
insert_sort keys = foldr f [] keys
where f key [] = [key]
f key acc = insert key acc
insert y [] = [y]
insert y (x:xs)
| x < y = x : insert y xs
| otherwise = y : x : xs
merge_sort :: (Ord a, Show a) => [a] -> [a]
merge_sort (x:[]) = [x]
merge_sort keys = merge (merge_sort (take len keys)) (merge_sort …假设我想编写一个函数来判断给定的整数是否为素数,我应该使用哪种类型的签名？
isPrime :: Int -> Bool
要么
isPrime :: (Integral a) => a -> Bool
有什么不同？是否有特别的理由选择一个而不是另一个？
如果是这样,我应该在哪些情况下分别使用这两种？
我们的项目主要由两部分组成
unmanagedJars设置依赖于根项目下的子项目.问题是如何在编译根项目之前组装着色项目.否则,根项目将无法编译,因为着色jar中的这些类不可用.
运行Cassandra Daemon时,我遇到了以下异常.我从1.2后备箱运行.
WARN 14:47:51,038 error reading saved cache /home/manuzhang/cassandra/saved_caches/system-local-KeyCache-b.db
java.lang.NullPointerException
at org.apache.cassandra.cache.AutoSavingCache.loadSaved(AutoSavingCache.java:141)
at org.apache.cassandra.db.ColumnFamilyStore.<init>(ColumnFamilyStore.java:237)
at org.apache.cassandra.db.ColumnFamilyStore.createColumnFamilyStore(ColumnFamilyStore.java:340)
at org.apache.cassandra.db.ColumnFamilyStore.createColumnFamilyStore(ColumnFamilyStore.java:312)
at org.apache.cassandra.db.Table.initCf(Table.java:332)
at org.apache.cassandra.db.Table.<init>(Table.java:265)
at org.apache.cassandra.db.Table.open(Table.java:110)
at org.apache.cassandra.db.Table.open(Table.java:88)
at org.apache.cassandra.db.SystemTable.checkHealth(SystemTable.java:284)
at org.apache.cassandra.service.CassandraDaemon.setup(CassandraDaemon.java:168)
at org.apache.cassandra.service.CassandraDaemon.activate(CassandraDaemon.java:318)
at org.apache.cassandra.service.CassandraDaemon.main(CassandraDaemon.java:361)
这里是保存缓存的地方:
manuzhang@manuzhang-U24E:~/cassandra/saved_caches$ ls -l
total 12
-rw-rw-r-- 1 manuzhang manuzhang 156 Aug 7 13:09 system-local-KeyCache-b.db
-rw-rw-r-- 1 manuzhang manuzhang 60 Aug 7 13:09 system-schema_columnfamilies-KeyCache-b.db
-rw-rw-r-- 1 manuzhang manuzhang 60 Aug 7 13:09 system-schema_columns-KeyCache-b.db
此外,无法加载系统表文件.
ERROR 17:03:16,637 Fatal exception during initialization
org.apache.cassandra.config.ConfigurationException: Found system table files, but …我一直在研究99个Haskell问题的问题67A.问题是从给定的字符串构造树:"x(y,a(,b))" => Branch 'x' (Branch 'y' Empty Empty) (Branch 'a' Empty (Branch 'b' Empty Empty))
使用的一个解决方案Parsec如下:
import Text.Parsec.String
import Text.Parsec hiding (Empty)
pTree :: Parser (Tree Char)
pTree = do
pBranch <|> pEmpty
pBranch = do
a <- letter
char '('
t0 <- pTree
char ','
t1 <- pTree
char ')'
return $ Branch a t0 t1
pEmpty =
return Empty
stringToTree str =
case parse pTree "" str of
Right t -> …我想尝试HBase-0.94独立模式,并按照快速入门中的说明进行操作.
我启动hbase start-hbase.sh并启动hbase shell
似乎我的master无法初始化,因为我的create table命令总是失败如下:
hbase(main):001:0> create 't1', 'cf'
ERROR: org.apache.hadoop.hbase.PleaseHoldException:
org.apache.hadoop.hbase.PleaseHoldException: Master is initializing
这是我的conf/hbase-site.xml档案:
<configuration>
<property>
<name>hbase.rootdir</name>
<value>/home/manuzhang/hbase</value>
</property>
<property>
<name>hbase.zookeeper.property.dataDir</name>
<value>/home/manuzhang/zookeeper</value>
</property>
</configuration>
和我的/etc/hosts档案:
127.0.0.1 localhost
127.0.0.1 jmx_host
127.0.1.1 manuzhang-U24E
# The following lines are desirable for IPv6 capable hosts
::1 ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
74.125.237.1 dl-ssl.google.com
我一直试图通过广播在Android 4.0模拟器上发送消息,并通过广播接收器获取该消息.我可以使用两个模拟器,例如5554到5556.但是,我无法从5554获取发送的消息给自己.这是我发送消息的方式:
SmsManager sms = SmsManager.getDefault();
sms.sendTextMessage(number, null, message, sentPI, deliveredPI);
这里的数字是模拟器的端口号
我正在测试mkdir函数来创建一个新目录:
folder = mkdir("./linux", 511);
要么
folder = mkdir("./linux", 0777);
要么
folder = mkdir("./linux", S_IRWXU | S_IRWXG | S_IRWXO);
正如您所看到的,我尝试授权该目录的完全权限,但这里是提出的ls -l | grep linux:
drwxr-xr-x 2 manuzhang manuzhang 4096 2012-01-04 06:53 linux
为什么我不能授权群组和其他人的写入权限？
更新:
奇怪的是,正如你们告诉我的那样,我试过了umask.它与两种umask(S_IWGRP)或umask(S_IWOTH)但未能有umask(S_IWGRP | S_IWOTH)任何想法？