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java异常

java异常

作者: qpan | 来源:发表于2018-04-21 14:29 被阅读6次
    • 分类:throwable的子类
      有 Error 和 Exception
    1. Error:一般是指与虚拟机相关的问题,如系统崩溃,虚拟机错误,内存空间不足,方法调用栈溢等。对于这类错 误的导致的应用程序中断,仅靠程序本身无法恢复和和预防,遇到这样的错误,建议让程序终止。
    /**
     * An {@code Error} is a subclass of {@code Throwable}
     * that indicates serious problems that a reasonable application
     * should not try to catch. Most such errors are abnormal conditions.
     * The {@code ThreadDeath} error, though a "normal" condition,
     * is also a subclass of {@code Error} because most applications
     * should not try to catch it.
     * <p>
     * A method is not required to declare in its {@code throws}
     * clause any subclasses of {@code Error} that might be thrown
     * during the execution of the method but not caught, since these
     * errors are abnormal conditions that should never occur.
     *
     * That is, {@code Error} and its subclasses are regarded as unchecked
     * exceptions for the purposes of compile-time checking of exceptions.
    
    1. Exception:表示程序可以处理的异常,可以捕获且可能恢复。遇到这类异常,应该尽可能处理异常,使程序恢复运行,而不应该随意终止异常。
    **
     * The class {@code Exception} and its subclasses are a form of
     * {@code Throwable} that indicates conditions that a reasonable
     * application might want to catch.
     *
     * <p>The class {@code Exception} and any subclasses that are not also
     * subclasses of {@link RuntimeException} are <em>checked
     * exceptions</em>.  Checked exceptions need to be declared in a
     * method or constructor's {@code throws} clause if they can be thrown
     * by the execution of the method or constructor and propagate outside
     * the method or constructor boundary.
    

    • 其中Exception可分为2种:
    1. RuntimeException:运行期异常,系统异常
      可以处理也可以不处理,编译器不强制用 try..catch 处理或用 throws 声明,所以系统异常也称为 unchecked 异常。
      eg:NullPointerException,IndexOutOfBoundsException,ClassCastException,ClassNotFoundException , IllegalArgumentException,UnsupportedOperationException。

    2. CheckedException: 也成编译器异常
      编译器强制普通异常必须 try..catch 处理或用 throws 声明继 续抛给上层调用方法处理
      eg:CloneNotSupportedException

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