Java ExceptionInInitializerError类

ExceptionInInitializerError类重点
抛出ExceptionInInitializerError错误表示静态初始值设定项中发生意外异常。即计算静态初始值设定项或静态变量初始值设定项期间发生异常。

ExceptionInInitializerError类源码

package java.lang;

/**
 * Signals that an unexpected exception has occurred in a static initializer.
 * An ExceptionInInitializerError is thrown to indicate that an
 * exception occurred during evaluation of a static initializer or the
 * initializer for a static variable.
 * 表示静态初始值设定项中发生意外异常。
 * 抛出ExceptionInInitializerError以指示在计算静态初始值设定项
 * 或静态变量初始值设定项期间发生异常。
 *
 * 
As of release 1.4, this exception has been retrofitted to conform to
 * the general purpose exception-chaining mechanism.  The "saved throwable
 * object" that may be provided at construction time and accessed via
 * the {@link #getException()} method is now known as the cause,
 * and may be accessed via the {@link Throwable#getCause()} method, as well
 * as the aforementioned "legacy method."
 * 从1.4版开始，此异常已进行了改装，以符合通用异常链接机制。
 * 可以在构造时提供并通过getException()方法访问的“保存的可丢弃对象”现在称为原因，
 * 可以通过 Throwable#getCause()方法以及前面提到的“遗留方法”访问
 *
 * @author  Frank Yellin
 * @since   1.1
 */
public class ExceptionInInitializerError extends LinkageError {
    /**
     * Use serialVersionUID from JDK 1.1.X for interoperability
     */
    private static final long serialVersionUID = 1521711792217232256L;

    /**
     * This field holds the exception if the
     * ExceptionInInitializerError(Throwable thrown) constructor was
     * used to instantiate the object
     *
     * @serial
     *
     */
    private Throwable exception;

    /**
     * Constructs an ExceptionInInitializerError with
     * null as its detail message string and with no saved
     * throwable object.
     * A detail message is a String that describes this particular exception.
     */
    public ExceptionInInitializerError() {
        initCause(null);  // Disallow subsequent initCause
    }

    /**
     * Constructs a new ExceptionInInitializerError class by
     * saving a reference to the Throwable object thrown for
     * later retrieval by the {@link #getException()} method. The detail
     * message string is set to null.
     *
     * @param thrown The exception thrown
     */
    public ExceptionInInitializerError(Throwable thrown) {
        initCause(null);  // Disallow subsequent initCause
        this.exception = thrown;
    }

    /**
     * Constructs an ExceptionInInitializerError with the specified detail
     * message string.  A detail message is a String that describes this
     * particular exception. The detail message string is saved for later
     * retrieval by the {@link Throwable#getMessage()} method. There is no
     * saved throwable object.
     *
     *
     * @param s the detail message
     */
    public ExceptionInInitializerError(String s) {
        super(s);
        initCause(null);  // Disallow subsequent initCause
    }

    /**
     * Returns the exception that occurred during a static initialization that
     * caused this error to be created.
     *
     * 
This method predates the general-purpose exception chaining facility.
     * The {@link Throwable#getCause()} method is now the preferred means of
     * obtaining this information.
     *
     * @return the saved throwable object of this
     *         ExceptionInInitializerError, or null
     *         if this ExceptionInInitializerError has no saved
     *         throwable object.
     */
    public Throwable getException() {
        return exception;
    }

    /**
     * Returns the cause of this error (the exception that occurred
     * during a static initialization that caused this error to be created).
     *
     * @return  the cause of this error or null if the
     *          cause is nonexistent or unknown.
     * @since   1.4
     */
    public Throwable getCause() {
        return exception;
    }
}