LAMBDA防爆pression扭转一个字符串 - Java的 [英] Lambda Expression to reverse a string - Java

问题描述

String[] planets = new String[] { "Mercury", "Venus", "Earth", "Mars", 
                  "Jupiter", "Saturn", "Uranus", "Neptune" };

我的星球名称的简单数组，我想扭转这种被添加到阵列（不是字符串顺序）每个名字。结果
我继续lambda语法奋斗：

I have a simple array of planet names and I want to reverse each name that was added to the array (not the string order).
I continue to struggle with lambda syntax:

Arrays.sort(planets, (first, second) -> new StringBuilder(first).reverse().toString());
System.out.println(Arrays.toString(planets));

目前我得到的：

在该行多个标记

  
• 的方法反向（）中的类型的StringBuilder 不适用于参数 （字符串）

  
• 类型不匹配：不能从字符串转换为 INT

  

• The method reverse() in the type StringBuilder is not applicable for the arguments (String)
• Type mismatch: cannot convert from String to int

响应：

感谢大家的建议... asList让我接近。我仍然没有正确地排序

Thank you all for suggestions... asList got me close. I still didn't sort correctly.

所以，我需要找到一种方法，使工作的Array.sort因为这是分配（取中的Array.sort和lambda它）。

So i need to find a way to make array.sort work because this was the assignment (to take array.sort and lambda it).

我ping的教练在这里要求澄清，但我的时间不多了。

I have pinged the instructor to ask for clarification here, but i am running out of time.

下面是我的工作，试图保持的Array.sort

Here is my work attempting to keep array.sort

            // lambda expression , long to short
        System.out.println("5) Sorted by length (descending):");
        Arrays.sort(planets, (first, second) -> second.length() - first.length());
        System.out.println(Arrays.toString(planets));   

        // lambda expression , reverse the name , then sort in ascending order
        // hint use  new StringBuilder(first).reverse().toString() to reverse the string
        System.out.println("6) Sorted in dictionary order of the reversed name (ascending)");
        Arrays.sort(planets, (first, second) -> new StringBuilder(first).reverse().toString().compareTo(second));
        System.out.println(Arrays.toString(planets));

        // lambda expression , reverse the name , then sort in descending order
        System.out.println("7) Sorted in dictionary order of the reversed name (descending)");
        Arrays.sort(planets, (first, second) -> new StringBuilder(second).reverse().toString().compareTo(first));
        System.out.println(Arrays.toString(planets));

我不能为我的生活弄清楚是什么在这里是所有前3 pressions让我完全相同的结果......每个那些给了我原来的数组排序时间最长最短的。

What I cannot for the life of me figure out here is that all 3 expressions get me exactly the same result... each of those gives me the original array sorted longest to shortest.

这是我的结果：

5）按长度排序（降序）：
[海王星，水星，木星，天王星，土星，金星，地球，火星]

5) Sorted by length (descending): [Neptune, Mercury, Jupiter, Uranus, Saturn, Venus, Earth, Mars]

6）逆转名字字典顺序（升序排序）
[海王星，水星，木星，天王星，土星，金星，地球，火星]

6) Sorted in dictionary order of the reversed name (ascending) [Neptune, Mercury, Jupiter, Uranus, Saturn, Venus, Earth, Mars]

7）排序在扭转名字典顺序（降序）
[海王星，水星，木星，天王星，土星，金星，地球，火星]

7) Sorted in dictionary order of the reversed name (descending) [Neptune, Mercury, Jupiter, Uranus, Saturn, Venus, Earth, Mars]

推荐答案

不使用流API和就地更新字符串替代的解决方案：

An alternative solution which does not use Stream API and updates the strings in-place:

Arrays.asList(planets).replaceAll(s -> new StringBuilder(s).reverse().toString());

演示：

String[] planets = new String[] { "Mercury", "Venus", "Earth", "Mars", 
        "Jupiter", "Saturn", "Uranus", "Neptune" };
Arrays.asList(planets).replaceAll(s -> new StringBuilder(s).reverse().toString());
System.out.println(Arrays.toString(planets));
// [yrucreM, suneV, htraE, sraM, retipuJ, nrutaS, sunarU, enutpeN]

这篇关于LAMBDA防爆pression扭转一个字符串 - Java的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！