java - lambda 不需要异常处理

Question

想象一下有这个方法:

public static File[] listDirectoryFiles(File directory) throws IllegalArgumentException {
    if (!directory.isDirectory())
        throw new IllegalArgumentException("Enter a directory");
    return directory.listFiles(File::isDirectory);
}

然后这样调用它:

File myDir = new File("C:\\Users\\bobby\\Downloads");
Arrays.asList(listDirectoryFiles(myDir)).forEach(System.out::println);

既然签名包含抛出IllegalArgumentException，为什么不需要实际try-catch对listDirectoryFiles的调用？

Answer 1

IllegalArgumentException是 RuntimeException 的子类:

RuntimeException and its subclasses are unchecked exceptions. Unchecked exceptions do not need to be declared in a method or constructor's throws clause if they can be thrown by the execution of the method or constructor and propagate outside the method or constructor boundary.