import sun.management.VMOptionCompositeData; //导入依赖的package包/类
/**
 * Constructs a <tt>VMOption</tt> object from a
 * {@link CompositeData CompositeData}.
 */
private VMOption(CompositeData cd) {
    // validate the input composite data
    VMOptionCompositeData.validateCompositeData(cd);

    this.name = VMOptionCompositeData.getName(cd);
    this.value = VMOptionCompositeData.getValue(cd);
    this.writeable = VMOptionCompositeData.isWriteable(cd);
    this.origin = VMOptionCompositeData.getOrigin(cd);
}
 

import sun.management.VMOptionCompositeData; //导入依赖的package包/类
/**
 * Returns a <tt>VMOption</tt> object represented by the
 * given <tt>CompositeData</tt>. The given <tt>CompositeData</tt>
 * must contain the following attributes:
 * <p>
 * <blockquote>
 * <table border>
 * <tr>
 *   <th align=left>Attribute Name</th>
 *   <th align=left>Type</th>
 * </tr>
 * <tr>
 *   <td>name</td>
 *   <td><tt>java.lang.String</tt></td>
 * </tr>
 * <tr>
 *   <td>value</td>
 *   <td><tt>java.lang.String</tt></td>
 * </tr>
 * <tr>
 *   <td>origin</td>
 *   <td><tt>java.lang.String</tt></td>
 * </tr>
 * <tr>
 *   <td>writeable</td>
 *   <td><tt>java.lang.Boolean</tt></td>
 * </tr>
 * </table>
 * </blockquote>
 *
 * @param cd <tt>CompositeData</tt> representing a <tt>VMOption</tt>
 *
 * @throws IllegalArgumentException if <tt>cd</tt> does not
 *   represent a <tt>VMOption</tt> with the attributes described
 *   above.
 *
 * @return a <tt>VMOption</tt> object represented by <tt>cd</tt>
 *         if <tt>cd</tt> is not <tt>null</tt>;
 *         <tt>null</tt> otherwise.
 */
public static VMOption from(CompositeData cd) {
    if (cd == null) {
        return null;
    }

    if (cd instanceof VMOptionCompositeData) {
        return ((VMOptionCompositeData) cd).getVMOption();
    } else {
        return new VMOption(cd);
    }

}