使用 Path 类在 Java 中的两个路径之间创建路径 [英] Creating a path between two paths in Java using the Path class

问题描述

this中的这句话到底是什么意思oracle java教程:

What does exactly mean this sentence from this oracle java tutorial:

如果只有一个路径，则无法构建相对路径包括一个根元素.如果两个路径都包含一个根元素，则构建相对路径的能力取决于系统.

A relative path cannot be constructed if only one of the paths includes a root element. If both paths include a root element, the capability to construct a relative path is system dependent.

系统依赖"是否仅意味着如果元素包含根，则它只能在已编写的平台特定语法中工作?我想这是他们唯一的意思.还有其他阅读方式吗?

With "system dipendent" do they mean only that if an element contains a root it will work only in the platform specific syntax that has been written? I guess it is the only thing they mean. Are there any other ways of reading that?

例如:

public class AnotherOnePathTheDust {
    public static void main (String []args)
    {
    Path p1 = Paths.get("home");
    Path p3 = Paths.get("home/sally/bar"); //with "/home/sally/bar" i would get an exception.
    // Result is sally/bar
    Path p1_to_p3 = p1.relativize(p3);
    // Result is ../..

    Path p3_to_p1 = p3.relativize(p1);
    System.out.println(p3_to_p1);   }
}

我使用/home/sally/bar"而不是home/sally/bar"(没有root)得到的例外是这个:

The exception that I get by using "/home/sally/bar" instead of "home/sally/bar" (without root) is this one:

 java.lang.IllegalArgumentException: 'other' is different type of Path

为什么不起作用?他们所说的与系统的冲突是什么?

Why does it not work? what is the conflict with the system that they mean?

推荐答案

因为 p1 和 p3 的根不同.

Because p1 and p3 has different root.

如果您使用/home/sally/bar"而不是home/sally/bar"作为p3，那么p3.getRoot() 将返回/ 但 p1.getRoot() 为空.

If you use use "/home/sally/bar" instead of "home/sally/bar" for p3, then p3.getRoot() will return / but p1.getRoot() is null.

阅读以下代码(来自http://cr.openjdk.java.net/~alanb/6863864/webrev.00/src/windows/classes/sun/nio/fs/WindowsPath.java-.html Line374-375):

You'll know why you got this exception after you read following codes (comes from http://cr.openjdk.java.net/~alanb/6863864/webrev.00/src/windows/classes/sun/nio/fs/WindowsPath.java-.html Line374-375):

// can only relativize paths of the same type
if (this.type != other.type)
     throw new IllegalArgumentException("'other' is different type of Path");

这篇关于使用 Path 类在 Java 中的两个路径之间创建路径的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！