exceptions - Exception Matching

最新推荐文章于 2021-03-02 06:52:59 发布

原创最新推荐文章于 2021-03-02 06:52:59 发布 · 670 阅读

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本文通过一个具体的Java代码示例，深入探讨了异常处理的最佳实践，强调了只捕获我们知道如何处理的异常的重要性。代码展示了不同类型的异常如何被捕获，并解释了异常层次结构的概念。

// exceptions/Human.java
// (c)2017 MindView LLC: see Copyright.txt
// We make no guarantees that this code is fit for any purpose.
// Visit http://OnJava8.com for more book information.
// Catching exception hierarchies

class Annoyance extends Exception {}

class Sneeze extends Annoyance {}

public class Human {
  public static void main(String[] args) {
    // Catch the exact type:
    try {
      throw new Sneeze();
    } catch (Sneeze s) {
      System.out.println("Caught Sneeze");
    } catch (Annoyance a) { // warning: unreachable catch clause
      System.out.println("Caught Annoyance");
    }
    // Catch the base type:
    try {
      throw new Sneeze();
    } catch (Annoyance a) {
      System.out.println("Caught Annoyance");
    }

    // try {
    //   throw new Sneeze();
    // } catch (Annoyance a) {
    //   System.out.println("Caught Annoyance");
    // } catch (Sneeze s) { // Compile error
    //   System.out.println("Caught Sneeze");
    // }
  }
}
/* Output:
Caught Sneeze
Caught Annoyance
*/

One important guideline in exception handling: Don't catch an exception unless we know what to do with it.

references:

1. On Java 8 - Bruce Eckel

2. https://github.com/wangbingfeng/OnJava8-Examples/blob/master/exceptions/Human.java