java - getenv() 的异常处理程序

Question

如何处理此类行代码的 NullPointerException 和 SecurityException:

public final static String PROJECT_DIR = System.getenv().get("HOME") + "/Projects/MyTestProject";

用 try/catch 包装就足够了？如果是这样，我该如何区分它是 NullPointerException 或 SecurityException？

如果 getenv() 不可用或其他原因，是否有任何最佳实践将其存储在属性中？

Answer 1

在类初始值设定项中初始化final static String。抛出一个描述问题的新异常(未设置，不允许)。例如:

public final static String PROJECT_DIR;

static {
     try {
       Map<String, String> env = System.getenv();

       if (!env.contains("HOME")) {
           throw new AssertionError("HOME not set as environment variable");
       }

       PROJECT_DIR = env.get("HOME") + "/Projects/MyTestProject";
     } catch (SecurityException e) {
       throw new AssertionError("Security policy doesn't allow access to system environment", e);
     }
 }