Java中使用stream.sorted()对带数字后缀的字符串排序异常问题

Hey there! Let's break down why your sorted result isn't turning out like you expected.

问题根源 #

Right now, you're comparing the substrings after "-" as plain text, which uses lexicographical (dictionary) order instead of numeric order. That's why "15" gets sorted before "4" — because the character '1' comes before '4' in the dictionary, even though 15 is a bigger number.

修复代码 #

You need to convert those substrings into integers first, then compare their numeric values instead. Here's how to adjust your sorted logic:

}).map(c -> { 
    System.out.println(c); 
    return c; 
}).distinct() 
.sorted((c1, c2) -> {
    // Extract the numeric part after "-" and convert to integer
    int num1 = Integer.parseInt(c1.substring(c1.indexOf("-") + 1));
    int num2 = Integer.parseInt(c2.substring(c2.indexOf("-") + 1));
    // Compare the integers directly
    return Integer.compare(num1, num2);
})
.collect(Collectors.toList());

为什么这样有效？ #

• c1.indexOf("-") + 1 skips the "-" character to get the start of the numeric part
• Integer.parseInt(...) converts that substring into an actual integer value
• Integer.compare(num1, num2) does a proper numeric comparison, so 4 < 9 < 15 like you expect

With this change, your final list will be [sg-1, sg-4, sg-9, sg-15] — exactly what you wanted!

内容的提问来源于stack exchange，提问作者Igor K