[英]Recieving Comparator Class type
我有两个比较器。 一个用于按首字母对单词排序(仅用于元音单词的排序)
public class FirstLetterComparator extends ComparatorType {
@Override
public int compare(String o1, String o2) {
String upperObject1 = o1.toUpperCase();
String upperObject2 = o2.toUpperCase();
return upperObject1.charAt(0) - upperObject2.charAt(0);
}
}
另一个用于按长度/元音计数系数排序(用于排序类中的所有单词)
public class VowelColComparator extends ComparatorType {
String vowelGroup = "AEIOUaeiou";
@Override
public int compare(String o1, String o2) {
int vCount1 = getVowelCount(o1);
int vCount2 = getVowelCount(o2);
float compareCoef1 = o1.length()/vCount1;
float compareCoef2 = o2.length()/vCount2;
return (int)(compareCoef1 - compareCoef2);
}
public int getVowelCount(String word){
int vowelCount = 0;
for (int i = 0; i < word.length(); i++){
char ch = word.charAt(i);
for (int j = 0; j < vowelGroup.length(); j++){
char v = vowelGroup.charAt(j);
if(ch == v)
vowelCount++;
}
}
return vowelCount;
}
和他们的超类
public class ComparatorType implements Comparator<String> {
@Override
public int compare(String o1, String o2) {
return 0;
}
}
在排序类中,我有两种类似的方法可以对列表进行排序
public class SortWords {
public static void sortVowelCol(String text, String regex){
Scanner scanner = new Scanner(text);
List<String> words = new ArrayList<>();
System.out.println();
System.out.println("Task1:");
while (scanner.hasNext()){
String word = scanner.next();
if(word.matches(regex)){
words.add(word);
}
}
Collections.sort(words, new VowelColComparator());
int lineCounter = 1;
System.out.println();
System.out.println();
System.out.println("Sorted Words:");
lineCounter = 1;
for(String w : words){
if(lineCounter == 12) {
System.out.print(w + "\n");
lineCounter = 0;
}
else
System.out.print(w + " ");
lineCounter++;
}
}
public static void sortVowelWords(String text, String regex) {
Scanner scanner = new Scanner(text);
List<String> vowelWords = new ArrayList<>();
System.out.println();
System.out.println("Task2: ");
while(scanner.hasNext()){
String word = scanner.next();
if(word.matches(regex)){
vowelWords.add(word);
}
}
Collections.sort(vowelWords, new FirstLetterComparator());
System.out.println();
System.out.println();
System.out.println("Sorted List:");
int lineCounter = 1;
for(String w : vowelWords){
if(lineCounter == 12) {
System.out.print(w + "\n");
lineCounter = 0;
}
else
System.out.print(w + " ");
lineCounter++;
}
}
}
主班
public class Main {
public static void main(String[] args) {
// write your code here
SingletonText.getInstance().parse();
SingletonText.getInstance().print();
SortWords.sortVowelWords(SingletonText.getInstance().getText().toString(), "^[AEIOUaeiou].*");
SortWords.sortVowelCol(SingletonText.getInstance().getText().toString(), "^[A-Za-z].*");
}
}
问题是我怎样才能在SortWords类中仅制作一个方法而不是两个类似的方法? 或如何获取Collections.sort参数的比较器类型?
您可以使用第三个参数来定义要使用的比较器。
public static void sort(String text, String regex, ComparatorType comp) {
// Code
Collections.sort(words, comp);
// Code
}
您需要像这样重构两个函数:
public static void sortVowel(String text, String regex,Comparator comparator) {
Scanner scanner = new Scanner(text);
List<String> vowelWords = new ArrayList<>();
System.out.println();
System.out.println("Task2: ");
while(scanner.hasNext()){
String word = scanner.next();
if(word.matches(regex)){
vowelWords.add(word);
}
}
Collections.sort(vowelWords, comparator);
System.out.println();
System.out.println();
System.out.println("Sorted List:");
int lineCounter = 1;
for(String w : vowelWords){
if(lineCounter == 12) {
System.out.print(w + "\n");
lineCounter = 0;
}
else
System.out.print(w + " ");
lineCounter++;
}
}
}
public static void sort(String text, String regex, String sortType) {
Collections.sort(words, sorttype.equals("Vowel") ? new VowelColComparator() : new FirstLetterComparator());
// Your code
}
然后我们可以这样叫
SortWords.sort(SingletonText.getInstance().getText().toString(), "^[AEIOUaeiou].*", "Vowel");
SortWords.sort(SingletonText.getInstance().getText().toString(), "^[A-Za-z].*", "firstletter");
首先,当给定字符串中没有元音时, VowelColComparator.getVowelCount可能会因除零而失败。 在比较长度和元音计数的比率时,可以执行以下操作:
float compareCoef1 = o1.length()/(vCount1+1);
float compareCoef2 = o2.length()/(vCount2+1);
您可以在ComparatorType类中使用工厂模式。 即ComparatorType类将根据正则表达式决定使用哪个实例(比较器)。 您可以根据需要添加任意多个比较器。
public abstract class ComparatorType implements Comparator<String> {
final public String vowelFirstLetterRegex = "^[A-Za-z].*";
final public String vowelColRegex = "^[AEIOUaeiou].*]";
public static ComparatorType getInstance(String regex) {
if (regex.equals(vowelColRegex))
return new VowelColComparator();
else if(regex.equals(vowelFirstLetterRegex ))
return new FirstLetterComparator();
return null;
}
}
并且您的SortWords类将具有以下方法:
public static void sort(String text, String regex){
Scanner scanner = new Scanner(text);
List<String> words = new ArrayList<>();
System.out.println();
System.out.println("Task1:");
while (scanner.hasNext()){
String word = scanner.next();
if(word.matches(regex)){
words.add(word);
}
}
Collections.sort(words, ComparatorType.getInstance(regex));
int lineCounter = 1;
System.out.println();
System.out.println();
System.out.println("Sorted Words:");
lineCounter = 1;
for(String w : words){
if(lineCounter == 12) {
System.out.print(w + "\n");
lineCounter = 0;
}
else
System.out.print(w + " ");
lineCounter++;
}
}
嗯,正如大家所说,您需要将Comparator<String>
作为第三个参数传递给您的方法:
sortVowelWords(String text, String regex, Comparator<String> cmp) {
//...
}
我想提出一些对比较器本身的改进。 使用lambda语法,可以更轻松地编写它们:
static final Comparator<String> CMP_BY_FIRST_CHAR =
Comparator.comparing(s -> Character.toUpperCase(s.charAt(0)));
static final Comparator<String> CMP_BY_VOWEL_COEF =
Comparator.comparing(s -> 1f * s.length() / s.replaceAll("[^AEIOUaeiou]+", "").length());
在第二个比较器中,我添加了显式强制类型转换为float
以正确处理可能的无穷大值。
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