在 Java 8 中以不区分大小写的方式对字符串值进行排序
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Sorting string value in a case-insensitive manner in Java 8
提问by Learn Hadoop
How do I sort string values in case-insensitive order in the following?
如何按以下不区分大小写的顺序对字符串值进行排序？
List<Employee> listofEmployees = Arrays.asList(
new Employee(1, "aaa", Arrays.asList(123, 345, 678)),
new Employee(1, "bbb", Arrays.asList(91011, 121314, 1516117)),
new Employee(2, "ccc", Arrays.asList(181920, 212223, 242526)),
new Employee(3, "ddd", Arrays.asList(272829, 303132, 333435)),
new Employee(4, "BBB", Arrays.asList(29, 332, 33))
);
I wrote like this:
我是这样写的：
listofEmployees.stream().sorted(Comparator.comparing(Employee::getName).reversed())
.forEach(s -> System.out.println(s.getName()));
How do I pass a string case insensitive option here?
如何在此处传递字符串不区分大小写的选项？
回答by Hadi J
Try this
试试这个
Comparator.comparing(Employee::getName, String.CASE_INSENSITIVE_ORDER)
回答by Oleksandr Pyrohov
As @Tree suggested in comments, one can use the java.text.Collatorfor a case-insensitive and locale-sensitive Stringcomparison. The following shows how both case and accents could be ignored for US English:
正如@Tree 在评论中建议的那样，可以将java.text.Collator用于不区分大小写和区分区域设置的String比较。下面显示了如何在美国英语中忽略大小写和重音：
Collator collator = Collator.getInstance(Locale.US);
collator.setStrength(Collator.PRIMARY);
listOfEmployees.sort(Comparator.comparing(Employee::getName, collator.reversed()));
When collator strength is set to PRIMARY, then only PRIMARYdifferences are considered significant during comparison. Therefore, the following Strings are considered equivalent:
当 collator strength 设置为 时PRIMARY，则PRIMARY在比较期间仅将差异视为显着。因此，以下字符串被认为是等效的：
if (collator.compare("abc", "ABC") == 0) {
System.out.println("Strings are equivalent");
}
回答by Schidu Luca
You can specify it as the second argument to ignore cases:
您可以将其指定为忽略大小写的第二个参数：
Comparator.comparing(Employee::getName, String::compareToIgnoreCase).reversed()
回答by shakhawat
This is one of many ways:
这是许多方法之一：
listofEmployees.stream()
.sorted((o1, o2) -> o1.getName().compareToIgnoreCase(o2.getName()))
.forEach(s -> System.out.println(s.getName()));
回答by genhernandez
It looks like there is a Comparator that orders String objects as by compareToIgnoreCase, you can read the documentation here: https://docs.oracle.com/javase/8/docs/api/java/lang/String.html#CASE_INSENSITIVE_ORDER
看起来有一个比较器通过 compareToIgnoreCase 对字符串对象进行排序，您可以在这里阅读文档：https: //docs.oracle.com/javase/8/docs/api/java/lang/String.html#CASE_INSENSITIVE_ORDER
回答by Ousmane D.
You can lowercase or uppercase it like this:
您可以像这样小写或大写：
listofEmployees.stream()
.sorted(Comparator.comparing((Employee e) -> e.getName()
.toLowerCase()) // or toUpperCase
.reversed())
.forEach(s -> System.out.println(s.getName()));
