Java：以数字方式对字符串数组进行排序
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Java: Sort a String array in a numeric way
提问by user934779
I have a String array that contains the following entries:
我有一个包含以下条目的字符串数组：
Array[0] = "70% Marc"
Array[1] = "50% Marc"
Array[2] = "100% Marc"
Array[3] = "20% Marc"
And I would like to sort this array descending.
When I use Arrays.sort(Array)then it does sort it descending but the 100% Marcis at the bottom (because it only looks at the first character to sort it). I want it to be sorted like this:
我想对这个数组进行降序排序。当我使用Arrays.sort(Array)then 时，它确实降序排序，但100% Marcis 在底部（因为它只查看第一个字符进行排序）。我希望它像这样排序：
"100% Marc"
"70% Marc"
"50% Marc"
"20% Marc"
How can I do that?
我怎样才能做到这一点？
回答by Bala R
Write your own CustomStringComparatorand use it with the sort method.
编写您自己的CustomStringComparator并将其与 sort 方法一起使用。
public class CustomStringComparator implements Comparator<String>{
@Override
public int compare(String str1, String str2) {
// extract numeric portion out of the string and convert them to int
// and compare them, roughly something like this
int num1 = Integer.parseInt(str1.substring(0, str1.indexOf("%") - 1));
int num2 = Integer.parseInt(str2.substring(0, str2.indexOf("%") - 1));
return num1 - num2;
}
}
回答by Swaranga Sarma
You have to use a custom Comparator. Basically in your method compare()you will write the logic to order two Strings.
您必须使用自定义Comparator。基本上在您的方法中，compare()您将编写逻辑来订购两个Strings。
回答by David Moreno García
You will need a custom comparator:
您将需要一个自定义比较器：
import java.util.Comparator;
public class CustomComparator implements Comparator<String>{
@Override
public int compare(String firstString, String secondString) {
int number1 = Integer.parseInt(firstString.substring(0, firstString.indexOf('%') - 1);
int number2 = Integer.parseInt(secondString.substring(0, secondString.indexOf('%') - 1);
return number1.compareTo(number2);
}
}
Use this comparator with something like this:
将此比较器用于以下内容：
List<String> entries = new ArrayList<String>();
entries.add("70% Marc");
entries.add("50% Marc");
entries.add("100% Marc");
entries.add("20% Marc");
CustomComparator comparator = new CustomComparator();
Collections.sort(entries, comparator);
回答by Bozho
You'd need to implement a custom Comparator<String>that handles the comparison by removing the percent sign:
您需要Comparator<String>通过删除百分号来实现处理比较的自定义：
public int compare(String str1, String str2) {
Integer number1 = Integer.parseInt(str1.substring(0, str1.length - 1));
Integer number2 = Integer.parseInt(str1.substring(0, str2.length - 1));
return number1.compareTo(number2);
// or use primitives, and then: return (x < y) ? -1 : ((x == y) ? 0 : 1);
// but that's harder to read
}
The comparison itself can be done by using the Integerwrapper, the code that I pasted (taken from the wrapper), or guava's Ints.compare(int1, int2)
比较本身可以通过使用Integer包装器、我粘贴的代码（取自包装器）或番石榴的Ints.compare(int1, int2)
Then use Collections.sort(array, comparator)
然后使用 Collections.sort(array, comparator)
回答by dougajmcdonald
It's not looking at the first character, it's sorting based on a string value as that's what you have in your array.
它不是查看第一个字符，而是基于字符串值进行排序，因为这就是数组中的内容。
I would suggest storing two fields,
我建议存储两个字段，
Array[0,0] = 50; Array[0,1] = "Marc"
数组[0,0] = 50; 数组[0,1] = "马克"
And then sorting based on the numeric field, if that's the behaviour you're after.
然后根据数字字段进行排序，如果这是您所追求的行为。
