system.html

API資料大全

<A NAME="setProperty(java.lang.String, java.lang.String)"><!-- --></A><H3>
setProperty</H3>
<PRE>
public static <A HREF="../../java/lang/String.html">String</A> <B>setProperty</B>(<A HREF="../../java/lang/String.html">String</A>&nbsp;key,
                                 <A HREF="../../java/lang/String.html">String</A>&nbsp;value)</PRE>
<DL>
<DD>Sets the system property indicated by the specified key. 
 <p>
 First, if a security manager exists, its 
 <code>SecurityManager.checkPermission</code> method
 is called with a <code>PropertyPermission(key, "write")</code>
 permission. This may result in a SecurityException being thrown.
 If no exception is thrown, the specified property is set to the given
 value.
 <p><DD><DL>
<DT><B>Parameters:</B><DD><CODE>key</CODE> - the name of the system property.<DD><CODE>value</CODE> - the value of the system property.<DT><B>Returns:</B><DD>the previous value of the system property,
             or <code>null</code> if it did not have one.<DT><B>Throws:</B><DD><CODE><A HREF="../../java/lang/SecurityException.html">SecurityException</A></CODE> - if a security manager exists and its  
             <code>checkPermission</code> method doesn't allow 
             setting of the specified property.<DD><CODE><A HREF="../../java/lang/NullPointerException.html">NullPointerException</A></CODE> - if <code>key</code> is
             <code>null</code>.<DD><CODE><A HREF="../../java/lang/IllegalArgumentException.html">IllegalArgumentException</A></CODE> - if <code>key</code> is empty.<DT><B>Since: </B><DD>1.2</DD>
<DT><B>See Also: </B><DD><A HREF="../../java/lang/System.html#getProperty(java.lang.String)"><CODE>getProperty(java.lang.String)</CODE></A>, 
<A HREF="../../java/lang/System.html#getProperty(java.lang.String)"><CODE>getProperty(java.lang.String)</CODE></A>, 
<A HREF="../../java/lang/System.html#getProperty(java.lang.String, java.lang.String)"><CODE>getProperty(java.lang.String, java.lang.String)</CODE></A>, 
<A HREF="../../java/util/PropertyPermission.html"><CODE>PropertyPermission</CODE></A>, 
<A HREF="../../java/lang/SecurityManager.html#checkPermission(java.security.Permission)"><CODE>SecurityManager.checkPermission(java.security.Permission)</CODE></A></DL>
</DD>
</DL>
<HR>

<A NAME="getenv(java.lang.String)"><!-- --></A><H3>
getenv</H3>
<PRE>
public static <A HREF="../../java/lang/String.html">String</A> <B>getenv</B>(<A HREF="../../java/lang/String.html">String</A>&nbsp;name)</PRE>
<DL>
<DD><B>Deprecated.</B>&nbsp;<I>The preferred way to extract system-dependent information
             is the system properties of the
             <code>java.lang.System.getProperty</code> methods and the
             corresponding <code>get</code><em>TypeName</em> methods of
             the <code>Boolean</code>, <code>Integer</code>, and
             <code>Long</code> primitive types.  For example:
 <blockquote><pre>
     String classPath = System.getProperty("java.class.path",".");
 <br>
     if (Boolean.getBoolean("myapp.exper.mode"))
         enableExpertCommands();
 </pre></blockquote></I>
<P>
<DD>Gets an environment variable. An environment variable is a
 system-dependent external variable that has a string value.<DD><DL>
<DT><B>Parameters:</B><DD><CODE>name</CODE> - of the environment variable<DT><B>Returns:</B><DD>the value of the variable, or <code>null</code> if the variable
           is not defined.<DT><B>See Also: </B><DD><A HREF="../../java/lang/Boolean.html#getBoolean(java.lang.String)"><CODE>Boolean.getBoolean(java.lang.String)</CODE></A>, 
<A HREF="../../java/lang/Integer.html#getInteger(java.lang.String)"><CODE>Integer.getInteger(java.lang.String)</CODE></A>, 
<A HREF="../../java/lang/Integer.html#getInteger(java.lang.String, int)"><CODE>Integer.getInteger(java.lang.String, int)</CODE></A>, 
<A HREF="../../java/lang/Integer.html#getInteger(java.lang.String, java.lang.Integer)"><CODE>Integer.getInteger(java.lang.String, java.lang.Integer)</CODE></A>, 
<A HREF="../../java/lang/Long.html#getLong(java.lang.String)"><CODE>Long.getLong(java.lang.String)</CODE></A>, 
<A HREF="../../java/lang/Long.html#getLong(java.lang.String, long)"><CODE>Long.getLong(java.lang.String, long)</CODE></A>, 
<A HREF="../../java/lang/Long.html#getLong(java.lang.String, java.lang.Long)"><CODE>Long.getLong(java.lang.String, java.lang.Long)</CODE></A>, 
<A HREF="../../java/lang/System.html#getProperties()"><CODE>getProperties()</CODE></A>, 
<A HREF="../../java/lang/System.html#getProperty(java.lang.String)"><CODE>getProperty(java.lang.String)</CODE></A>, 
<A HREF="../../java/lang/System.html#getProperty(java.lang.String, java.lang.String)"><CODE>getProperty(java.lang.String, java.lang.String)</CODE></A></DL>
</DD>
</DL>
<HR>

<A NAME="exit(int)"><!-- --></A><H3>
exit</H3>
<PRE>
public static void <B>exit</B>(int&nbsp;status)</PRE>
<DL>
<DD>Terminates the currently running Java Virtual Machine. The 
 argument serves as a status code; by convention, a nonzero status 
 code indicates abnormal termination. 
 <p>
 This method calls the <code>exit</code> method in class 
 <code>Runtime</code>. This method never returns normally. 
 <p>
 The call <code>System.exit(n)</code> is effectively equivalent to 
 the call:
 <blockquote><pre>
 Runtime.getRuntime().exit(n)
 </pre></blockquote><DD><DL>
<DT><B>Parameters:</B><DD><CODE>status</CODE> - exit status.<DT><B>Throws:</B><DD><CODE><A HREF="../../java/lang/SecurityException.html">SecurityException</A></CODE> - if a security manager exists and its <code>checkExit</code> 
        method doesn't allow exit with the specified status.<DT><B>See Also: </B><DD><A HREF="../../java/lang/Runtime.html#exit(int)"><CODE>Runtime.exit(int)</CODE></A></DL>
</DD>
</DL>
<HR>

<A NAME="gc()"><!-- --></A><H3>
gc</H3>
<PRE>
public static void <B>gc</B>()</PRE>
<DL>
<DD>Runs the garbage collector.
 <p>
 Calling the <code>gc</code> method suggests that the Java Virtual 
 Machine expend effort toward recycling unused objects in order to 
 make the memory they currently occupy available for quick reuse. 
 When control returns from the method call, the Java Virtual 
 Machine has made a best effort to reclaim space from all discarded 
 objects.
 <p>
 The call <code>System.gc()</code> is effectively equivalent to the 
 call:
 <blockquote><pre>
 Runtime.getRuntime().gc()
 </pre></blockquote><DD><DL>
<DT><B>See Also: </B><DD><A HREF="../../java/lang/Runtime.html#gc()"><CODE>Runtime.gc()</CODE></A></DL>
</DD>
</DL>
<HR>

<A NAME="runFinalization()"><!-- --></A><H3>
runFinalization</H3>
<PRE>
public static void <B>runFinalization</B>()</PRE>
<DL>
<DD>Runs the finalization methods of any objects pending finalization.
 <p>
 Calling this method suggests that the Java Virtual Machine expend 
 effort toward running the <code>finalize</code> methods of objects 
 that have been found to be discarded but whose <code>finalize</code> 
 methods have not yet been run. When control returns from the 
 method call, the Java Virtual Machine has made a best effort to 
 complete all outstanding finalizations. 
 <p>
 The call <code>System.runFinalization()</code> is effectively 
 equivalent to the call:
 <blockquote><pre>
 Runtime.getRuntime().runFinalization()
 </pre></blockquote><DD><DL>
<DT><B>See Also: </B><DD><A HREF="../../java/lang/Runtime.html#runFinalization()"><CODE>Runtime.runFinalization()</CODE></A></DL>
</DD>
</DL>
<HR>

<A NAME="runFinalizersOnExit(boolean)"><!-- --></A><H3>
runFinalizersOnExit</H3>
<PRE>
public static void <B>runFinalizersOnExit</B>(boolean&nbsp;value)</PRE>
<DL>
<DD><B>Deprecated.</B>&nbsp;<I>This method is inherently unsafe.  It may result in
 	    finalizers being called on live objects while other threads are
      concurrently manipulating those objects, resulting in erratic
	    behavior or deadlock.</I>
<P>
<DD>Enable or disable finalization on exit; doing so specifies that the
 finalizers of all objects that have finalizers that have not yet been
 automatically invoked are to be run before the Java runtime exits.
 By default, finalization on exit is disabled.
 
 <p>If there is a security manager, 
 its <code>checkExit</code> method is first called
 with 0 as its argument to ensure the exit is allowed. 
 This could result in a SecurityException.<DD><DL>
<DT><B>Parameters:</B><DD><CODE>value</CODE> - indicating enabling or disabling of finalization<DT><B>Throws:</B><DD><CODE><A HREF="../../java/lang/SecurityException.html">SecurityException</A></CODE> - if a security manager exists and its <code>checkExit</code> 
        method doesn't allow the exit.<DT><B>Since: </B><DD>JDK1.1</DD>
<DT><B>See Also: </B><DD><A HREF="../../java/lang/Runtime.html#exit(int)"><CODE>Runtime.exit(int)</CODE></A>, 
<A HREF="../../java/lang/Runtime.html#gc()"><CODE>Runtime.gc()</CODE></A>, 
<A HREF="../../java/lang/SecurityManager.html#checkExit(int)"><CODE>SecurityManager.checkExit(int)</CODE></A></DL>
</DD>
</DL>
<HR>

<A NAME="load(java.lang.String)"><!-- --></A><H3>
load</H3>
<PRE>
public static void <B>load</B>(<A HREF="../../java/lang/String.html">String</A>&nbsp;filename)</PRE>
<DL>
<DD>Loads a code file with the specified filename from the local file 
 system as a dynamic library. The filename 
 argument must be a complete pathname. 
 <p>
 The call <code>System.load(name)</code> is effectively equivalent 
 to the call:
 <blockquote><pre>
 Runtime.getRuntime().load(name)
 </pre></blockquote><DD><DL>
<DT><B>Parameters:</B><DD><CODE>filename</CODE> - the file to load.<DT><B>Throws:</B><DD><CODE><A HREF="../../java/lang/SecurityException.html">SecurityException</A></CODE> - if a security manager exists and its  
             <code>checkLink</code> method doesn't allow 
             loading of the specified dynamic library<DD><CODE><A HREF="../../java/lang/UnsatisfiedLinkError.html">UnsatisfiedLinkError</A></CODE> - if the file does not exist.<DT><B>See Also: </B><DD><A HREF="../../java/lang/Runtime.html#load(java.lang.String)"><CODE>Runtime.load(java.lang.String)</CODE></A>, 
<A HREF="../../java/lang/SecurityManager.html#checkLink(java.lang.String)"><CODE>SecurityManager.checkLink(java.lang.String)</CODE></A></DL>
</DD>
</DL>
<HR>

<A NAME="loadLibrary(java.lang.String)"><!-- --></A><H3>
loadLibrary</H3>
<PRE>
public static void <B>loadLibrary</B>(<A HREF="../../java/lang/String.html">String</A>&nbsp;libname)</PRE>
<DL>
<DD>Loads the system library specified by the <code>libname</code> 
 argument. The manner in which a library name is mapped to the 
 actual system library is system dependent.
 <p>
 The call <code>System.loadLibrary(name)</code> is effectively 
 equivalent to the call
 <blockquote><pre>
 Runtime.getRuntime().loadLibrary(name)
 </pre></blockquote><DD><DL>
<DT><B>Parameters:</B><DD><CODE>libname</CODE> - the name of the library.<DT><B>Throws:</B><DD><CODE><A HREF="../../java/lang/SecurityException.html">SecurityException</A></CODE> - if a security manager exists and its  
             <code>checkLink</code> method doesn't allow 
             loading of the specified dynamic library<DD><CODE><A HREF="../../java/lang/UnsatisfiedLinkError.html">UnsatisfiedLinkError</A></CODE> - if the library does not exist.<DT><B>See Also: </B><DD><A HREF="../../java/lang/Runtime.html#loadLibrary(java.lang.String)"><CODE>Runtime.loadLibrary(java.lang.String)</CODE></A>, 
<A HREF="../../java/lang/SecurityManager.html#checkLink(java.lang.String)"><CODE>SecurityManager.checkLink(java.lang.String)</CODE></A></DL>
</DD>
</DL>
<HR>

<A NAME="mapLibraryName(java.lang.String)"><!-- --></A><H3>
mapLibraryName</H3>
<PRE>
public static <A HREF="../../java/lang/String.html">String</A> <B>mapLibraryName</B>(<A HREF="../../java/lang/String.html">String</A>&nbsp;libname)</PRE>
<DL>
<DD>Maps a library name into a platform-specific string representing
 a native library.<DD><DL>
<DT><B>Parameters:</B><DD><CODE>libname</CODE> - the name of the library.<DT><B>Returns:</B><DD>a platform-dependent native library name.<DT><B>Since: </B><DD>1.2</DD>
<DT><B>See Also: </B><DD><A HREF="../../java/lang/System.html#loadLibrary(java.lang.String)"><CODE>loadLibrary(java.lang.String)</CODE></A>, 
<A HREF="../../java/lang/ClassLoader.html#findLibrary(java.lang.String)"><CODE>ClassLoader.findLibrary(java.lang.String)</CODE></A></DL>
</DD>
</DL>
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