[英]How to sort ArrayList alphabetically then by number
这是排序之前的样子。 书名,年出版
我想按字母顺序对标题进行排序,然后再发布年份。
这是我当前排序之前的编码:
ArrayList BookList = new ArrayList();
BufferedReader br = new BufferedReader (new FileReader ("bookInput.txt"));
String str = br.readLine();
while (str!=null){
StringTokenizer st = new StringTokenizer(str,";");
String title = st.nextToken();
String yr = st.nextToken();
int year = Integer.parseInt(yr);
Book b1 = new Book (title,year);
BookList.add(b1);
str = br.readLine();
}
br.close();
//3(d)
System.out.println("List of Books" + "( " + BookList.size() + " record(s) ) ");
for (int i = 0; i < BookList.size(); i++){
Book b2 = (Book)BookList.get(i);
System.out.println("#" + (i+1) + " " + b2.getTitle() + " , " + b2.getYear());
}
我已经尝试了一切我知道的但是失败了failed
您可以使用Comparator
链,假设Book
类具有吸气剂:
BookList.sort(Comparator.comparing(Book::getTitle)
.thenComparingInt(Book::getYear));
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