java堆分配

Question

我试图像下面那样增加堆大小

    C:\Data\Guru\Code\Got\adminservice\adminservice>java -Xms512m -Xmx512m
Usage: java [-options] class [args...]
           (to execute a class)
   or  java [-options] -jar jarfile [args...]
           (to execute a jar file)

where options include:
    -client       to select the "client" VM
    -server       to select the "server" VM
    -hotspot      is a synonym for the "client" VM  [deprecated]
                  The default VM is client.

    -cp <class search path of directories and zip/jar files>
    -classpath <class search path of directories and zip/jar files>
                  A ; separated list of directories, JAR archives,
                  and ZIP archives to search for class files.
    -D<name>=<value>
                  set a system property
    -verbose[:class|gc|jni]
                  enable verbose output
    -version      print product version and exit
    -version:<value>
                  require the specified version to run
    -showversion  print product version and continue
    -jre-restrict-search | -jre-no-restrict-search
                  include/exclude user private JREs in the version search
    -? -help      print this help message
    -X            print help on non-standard options
    -ea[:<packagename>...|:<classname>]
    -enableassertions[:<packagename>...|:<classname>]
                  enable assertions
    -da[:<packagename>...|:<classname>]
    -disableassertions[:<packagename>...|:<classname>]
                  disable assertions
    -esa | -enablesystemassertions
                  enable system assertions
    -dsa | -disablesystemassertions
                  disable system assertions
    -agentlib:<libname>[=<options>]
                  load native agent library <libname>, e.g. -agentlib:hprof
                    see also, -agentlib:jdwp=help and -agentlib:hprof=help
    -agentpath:<pathname>[=<options>]
                  load native agent library by full pathname
    -javaagent:<jarpath>[=<options>]
                  load Java programming language agent, see java.lang.instrument

它给出了上面的帮助信息 - 这是否意味着它被分配了？

Answer 1

不，这意味着命令失败了，因为你没有说出要运行什么，比如Main类，例如。

java -Xms512m -Xmx512m com.x.MyClass

除此之外，您的选择是有效的，是的。

Answer 2

不，

您还必须提供要执行的类名或jar文件名。这些选项仅适用于虚拟机的一个实例。

如果您尝试更改应用程序服务器或开发环境中的堆分配，则必须查找如何在那里提供JVM选项，并将-Xms选项放入。