runtime.java

This is a resource based on j2me embedded,if you dont understand,you can connection with me .

     * @see     java.lang.SecurityManager#checkExec(java.lang.String)
     * @since 1.3
     */
    public Process exec(String cmdarray[], String envp[], File dir) 
	throws IOException {	
	cmdarray = (String[])cmdarray.clone();
	envp = (envp != null ? (String[])envp.clone() : null);

        if (cmdarray.length == 0) {
            throw new IndexOutOfBoundsException();            
        }
        for (int i = 0; i < cmdarray.length; i++) {
            if (cmdarray[i] == null) {
                throw new NullPointerException();
            }
        }
        if (envp != null) {
            for (int i = 0; i < envp.length; i++) {
                if (envp[i] == null) {
                    throw new NullPointerException();
                }
            }
        }
	SecurityManager security = System.getSecurityManager();
	if (security != null) {
	    security.checkExec(cmdarray[0]);
	}
        String path = (dir == null ? null : dir.getPath());
	return execInternal(cmdarray, envp, path);
    }

    /**
     * Returns the number of processors available to the Java virtual machine.
     *
     * <p> This value may change during a particular invocation of the virtual
     * machine.  Applications that are sensitive to the number of available
     * processors should therefore occasionally poll this property and adjust
     * their resource usage appropriately. </p>
     *
     * @return  the maximum number of processors available to the virtual
     *          machine; never smaller than one
     */
    //public native int availableProcessors();
    public int availableProcessors() {
       return 1;  // assume that CVM supports only one 
    }

    /**
     * Returns the amount of free memory in the Java Virtual Machine.
     * Calling the 
     * <code>gc</code> method may result in increasing the value returned 
     * by <code>freeMemory.</code>
     *
     * @return  an approximation to the total amount of memory currently
     *          available for future allocated objects, measured in bytes.
     */
    public native long freeMemory();

    /**
     * Returns the total amount of memory in the Java virtual machine.
     * The value returned by this method may vary over time, depending on 
     * the host environment.
     * <p>
     * Note that the amount of memory required to hold an object of any 
     * given type may be implementation-dependent.
     * 
     * @return  the total amount of memory currently available for current 
     *          and future objects, measured in bytes.
     */
    public native long totalMemory();

    /**
     * Returns the maximum amount of memory that the Java virtual machine will
     * attempt to use.  If there is no inherent limit then the value {@link
     * java.lang.Long#MAX_VALUE} will be returned. </p>
     *
     * @return  the maximum amount of memory that the virtual machine will
     *          attempt to use, measured in bytes
     */
    public native long maxMemory();

    /**
     * Runs the garbage collector.
     * Calling this 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 virtual machine has made 
     * its best effort to recycle all discarded objects. 
     * <p>
     * The name <code>gc</code> stands for "garbage 
     * collector". The virtual machine performs this recycling 
     * process automatically as needed, in a separate thread, even if the 
     * <code>gc</code> method is not invoked explicitly.
     * <p>
     * The method {@link System#gc()} is the conventional and convenient 
     * means of invoking this method. 
     */
    public native void gc();

    /* Wormhole for calling java.lang.ref.Finalizer.runFinalization */
    private static native void runFinalization0();

    /**
     * Runs the finalization methods of any objects pending finalization.
     * 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 virtual machine has made a best effort to 
     * complete all outstanding finalizations. 
     * <p>
     * The virtual machine performs the finalization process 
     * automatically as needed, in a separate thread, if the 
     * <code>runFinalization</code> method is not invoked explicitly. 
     * <p>
     * The method {@link System#runFinalization()} is the conventional 
     * and convenient means of invoking this method.
     *
     * @see     java.lang.Object#finalize()
     */
    public void runFinalization() {
	runFinalization0();
    }

    /**
     * Enables/Disables tracing of instructions.
     * If the <code>boolean</code> argument is <code>true</code>, this 
     * method suggests that the Java virtual machine emit debugging 
     * information for each instruction in the virtual machine as it 
     * is executed. The format of this information, and the file or other 
     * output stream to which it is emitted, depends on the host environment. 
     * The virtual machine may ignore this request if it does not support 
     * this feature. The destination of the trace output is system 
     * dependent. 
     * <p>
     * If the <code>boolean</code> argument is <code>false</code>, this 
     * method causes the virtual machine to stop performing the 
     * detailed instruction trace it is performing.
     *
     * @param   on   <code>true</code> to enable instruction tracing;
     *               <code>false</code> to disable this feature.
     */
    public native void traceInstructions(boolean on);

    /**
     * Enables/Disables tracing of method calls.
     * If the <code>boolean</code> argument is <code>true</code>, this 
     * method suggests that the Java virtual machine emit debugging 
     * information for each method in the virtual machine as it is 
     * called. The format of this information, and the file or other output 
     * stream to which it is emitted, depends on the host environment. The 
     * virtual machine may ignore this request if it does not support 
     * this feature.  
     * <p>
     * Calling this method with argument false suggests that the
     * virtual machine cease emitting per-call debugging information.
     *
     * @param   on   <code>true</code> to enable instruction tracing;
     *               <code>false</code> to disable this feature.
     */
    public native void traceMethodCalls(boolean on);

    /**
     * Loads the specified filename as a dynamic library. The filename 
     * argument must be a complete path name. 
     * From <code>java_g</code> it will automagically insert "_g" before the
     * ".so" (for example
     * <code>Runtime.getRuntime().load("/home/avh/lib/libX11.so");</code>).
     * <p>
     * First, if there is a security manager, its <code>checkLink</code> 
     * method is called with the <code>filename</code> as its argument. 
     * This may result in a security exception. 
     * <p>
     * This is similar to the method {@link #loadLibrary(String)}, but it 
     * accepts a general file name as an argument rather than just a library 
     * name, allowing any file of native code to be loaded.
     * <p>
     * The method {@link System#load(String)} is the conventional and 
     * convenient means of invoking this method.
     *
     * @param      filename   the file to load.
     * @exception  SecurityException  if a security manager exists and its  
     *             <code>checkLink</code> method doesn't allow 
     *             loading of the specified dynamic library
     * @exception  UnsatisfiedLinkError  if the file does not exist.
     * @see        java.lang.Runtime#getRuntime()
     * @see        java.lang.SecurityException
     * @see        java.lang.SecurityManager#checkLink(java.lang.String)
     */
    public void load(String filename) {
        load0(System.getCallerClass(), filename);
    }

    synchronized void load0(Class fromClass, String filename) {
	SecurityManager security = System.getSecurityManager();
	if (security != null) {
	    security.checkLink(filename);
	}
	if (!(new File(filename).isAbsolute())) {
	    throw new UnsatisfiedLinkError(
	        "Expecting an absolute path of the library: " + filename);
	}
	ClassLoader.loadLibrary(fromClass, filename, true);
    }

    /**
     * Loads the dynamic library with the specified library name. 
     * A file containing native code is loaded from the local file system 
     * from a place where library files are conventionally obtained. The 
     * details of this process are implementation-dependent. The 
     * mapping from a library name to a specific filename is done in a 
     * system-specific manner. 
     * <p>
     * First, if there is a security manager, its <code>checkLink</code> 
     * method is called with the <code>libname</code> as its argument. 
     * This may result in a security exception. 
     * <p>
     * The method {@link System#loadLibrary(String)} is the conventional 
     * and convenient means of invoking this method. If native
     * methods are to be used in the implementation of a class, a standard 
     * strategy is to put the native code in a library file (call it 
     * <code>LibFile</code>) and then to put a static initializer:
     * <blockquote><pre>
     * static { System.loadLibrary("LibFile"); }
     * </pre></blockquote>
     * within the class declaration. When the class is loaded and 
     * initialized, the necessary native code implementation for the native 
     * methods will then be loaded as well. 
     * <p>
     * If this method is called more than once with the same library 
     * name, the second and subsequent calls are ignored. 
     *
     * @param      libname   the name of the library.
     * @exception  SecurityException  if a security manager exists and its  
     *             <code>checkLink</code> method doesn't allow 
     *             loading of the specified dynamic library
     * @exception  UnsatisfiedLinkError  if the library does not exist.
     * @see        java.lang.SecurityException
     * @see        java.lang.SecurityManager#checkLink(java.lang.String)
     */
    public void loadLibrary(String libname) {
        loadLibrary0(System.getCallerClass(), libname); 
    }

    synchronized void loadLibrary0(Class fromClass, String libname) {
	SecurityManager security = System.getSecurityManager();
	if (security != null) {
	    security.checkLink(libname);
	}
	if (libname.indexOf((int)File.separatorChar) != -1) {
	    throw new UnsatisfiedLinkError(
    "Directory separator should not appear in library name: " + libname);
	}
	ClassLoader.loadLibrary(fromClass, libname, false);
    }

    /**
     * Creates a localized version of an input stream. This method takes 
     * an <code>InputStream</code> and returns an <code>InputStream</code> 
     * equivalent to the argument in all respects except that it is 
     * localized: as characters in the local character set are read from 
     * the stream, they are automatically converted from the local 
     * character set to Unicode. 
     * <p>
     * If the argument is already a localized stream, it may be returned 
     * as the result. 
     *
     * @param      in InputStream to localize
     * @return     a localized input stream
     * @see        java.io.InputStream
     * @see        java.io.BufferedReader#BufferedReader(java.io.Reader)
     * @see        java.io.InputStreamReader#InputStreamReader(java.io.InputStream)
     * @deprecated As of JDK&nbsp;1.1, the preferred way to translate a byte
     * stream in the local encoding into a character stream in Unicode is via
     * the <code>InputStreamReader</code> and <code>BufferedReader</code>
     * classes.
     *
    public InputStream getLocalizedInputStream(InputStream in) {
	return in;
    }
     */

    /**
     * Creates a localized version of an output stream. This method 
     * takes an <code>OutputStream</code> and returns an 
     * <code>OutputStream</code> equivalent to the argument in all respects 
     * except that it is localized: as Unicode characters are written to 
     * the stream, they are automatically converted to the local 
     * character set. 
     * <p>
     * If the argument is already a localized stream, it may be returned 
     * as the result. 
     *
     * deprecated As of JDK&nbsp;1.1, the preferred way to translate a
     * Unicode character stream into a byte stream in the local encoding is via
     * the <code>OutputStreamWriter</code>, <code>BufferedWriter</code>, and
     * <code>PrintWriter</code> classes.
     *
     * param      out OutputStream to localize
     * return     a localized output stream
     * see        java.io.OutputStream
     * see        java.io.BufferedWriter#BufferedWriter(java.io.Writer)
     * see        java.io.OutputStreamWriter#OutputStreamWriter(java.io.OutputStream)
     * see        java.io.PrintWriter#PrintWriter(java.io.OutputStream)
     *
    public OutputStream getLocalizedOutputStream(OutputStream out) {
	return out;
    }
     */

}