英文:
String method with array of integers
问题
请帮忙修改代码。我尝试过添加子字符串等方法来去除末尾的逗号。我该如何操作？
例如：将{1,2,3}转换为字符串后变成了"1,2,3,"。
public static String arrayToString(int[] numbers){String stringify = "";for (int index = 0; index < numbers.length; index++){stringify += numbers[index] + ", ";}return stringify;}
英文:
Please help with code. I have tried adding substring, etc, to remove the end comma. How can I do this?
Example: {1,2,3} to string is now "1,2,3,"
public static String arrayToString(int[] numbers){String stringify = "";for (int index = 0; index < numbers.length; index++){stringify = numbers[index] + ", ";}return stringify;}
答案1
得分: 2
最佳方式
删除整个方法。改用 Arrays.toString(int[])。为什么要重新编写核心功能呢？
Stream方式
return Arrays.stream(numbers).boxed().map(String::valueOf).collect(Collectors.joining(", "));
StringBuilder方式
StringBuilder out = new StringBuilder();for (int i = 0; i < numbers.length; i++) {if (i != 0) out.append(", ");out.append(numbers[i]);}return out.toString();
在循环中追加字符串是不好的做法（会浪费大量内存），所以不要这样做。上述策略的偏好顺序大致如上，最佳选项遥遥领先于其他方法。
英文:
Best way
Delete the entire method. Use Arrays.toString(int[]) instead. Why rewrite core functionality like this?
Stream way
return Arrays.stream(numbers).boxed().map(String::valueOf).collect(Collectors.joining(", "));
StringBuilder way
StringBuilder out = new StringBuilder();for (int i = 0; i < numbers.length; i++) {if (i != 0) out.append(", ");out.append(numbers[i]);}return out.toString();
Adding to a string in a loop is bad form (it wastes a ton of memory), so don't do that. The above strategies are in rough order of preference, with the top option miles ahead of the rest.
答案2
得分: 0
你可以将方法修改为以下形式：
public static String arrayToString(int[] numbers){String stringify = "";for (int index = 0; index < numbers.length; index++){stringify = numbers[index];if (index < numbers.length - 1) {stringify += ", ";}}return stringify;}
英文:
You can modify your method to the following one:
public static String arrayToString(int[] numbers){String stringify = "";for (int index = 0; index < numbers.length; index++){stringify = numbers[index];if (index < numbers.length - 1) {stringify += ", ";}}return stringify;}
答案3
得分: 0
我倾向于将其视为在每个数字之前都有一个分隔符，除了第一个数字之外。或者，同样地，每个数字之前都有一个分隔符，但第一个分隔符是空的。public static String arrayToString(int[] numbers){String separator = "";String stringify = "";for (int index = 0; index < numbers.length; index++){stringify += separator + numbers[index];separator = ", ";}return stringify;}注意，我将 `stringify` 的赋值修正为 `+=` 而不是 `=`，因为否则你只会得到最后一个数字。实际上，在实践中，我可能会使用 StringBuilder，但我想尽量保持原样。使用 StringBuilder，可以使用相同的分隔符技术。
英文:
I prefer to view this as having a separator before every number except for the first. Or, equally, that there's a separator before every number, but the first separator is empty.
public static String arrayToString(int[] numbers){String separator = "";String stringify = "";for (int index = 0; index < numbers.length; index++){stringify += separator + numbers[index];separator = ", "}return stringify;}
Note, I fixed the assignment to stringify to be += rather than =, since otherwise you're just getting the last number.
In practice, I'd probably use a StringBuilder, but I wanted to leave this as close to the original as possible. With a StringBuilder, the same separator technique can be used.
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