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我在Java和 初學者我想要做的Java 8如下：通執行時間，把他們在多頭排列
- 計算的執行時間我方法 - 具有
System.nanoTime， - 打發時間作爲流參數我的比較方法，
- 將這些值代入從長陣列[2]〜[5]，並返回該數組
我不知道如何實現這一點。我嘗試了不同的方式，但我遇到了錯誤，並沒有任何答案。以下是我迄今所做的：
import java.util.stream.Stream;
import java.io.*;
import java.nio.file.*;
import java.util.Arrays;
import java.util.Comparator;
import java.util.List;
import java.util.Map;
import java.util.function.Function;
import java.util.stream.Collectors;
import java.util.stream.LongStream;
import java.lang.Object;
import java.util.stream.IntStream;
/*
* To change this license header, choose License Headers in Project Properties.
* To change this template file, choose Tools | Templates
* and open the template in the editor.
*/
/**
*
* @author user
*/
public class WinneropsDB implements Winner{
private int getYear;
private int getWinnerAge;
private String getWinnerName;
private String getFilmTitle;
public WinneropsDB(String s) {
String[] Data = s.split(",",5);
getYear = Integer.parseInt(Data[1]);
getWinnerAge = Integer.parseInt(Data[2]);
getWinnerName = Data[3].substring(1,Data[3].length()-1);
getFilmTitle = Data[4].substring(1,Data[4].length()-1);
}
@Override
public String toString(){
return getYear+", "+getWinnerAge+", "+getWinnerName+", "+getFilmTitle;
}
public static Stream<Winner> loadData(String[] fileName) {
return Arrays.stream(fileName).flatMap(f -> {
try {
return Files.lines(Paths.get(f))
.filter(first -> !first.startsWith("#"))
.map(WinneropsDB:: new);
} catch (IOException e) {
System.out.println("file not found");
return null;
}
});
}
/**
*
* @param young
* @return
*/
public static Stream<Winner> youngWinners(Stream<Winner> young) {
return young.filter(w -> w.getWinnerAge() < 35)
.sorted(Comparator.comparing(Winner :: getWinnerName));
}
public static Stream<Winner> extreamWinners (Stream<Winner> mix){
long startTime = System.nanoTime();
Comparator<Winner> comparator = Comparator.comparing(Winner -> Winner.getWinnerName());
Stream<Winner> m = mix.sorted(comparator);
//Winner[] g = (Winner[]) m.toArray();
//System.out.println(g[0]);
Comparator<Winner> comparator1 = Comparator.comparing(Winner -> Winner.getWinnerAge());
Stream<Winner> m1 = m.sorted(comparator1);
Winner[] lis = m1.toArray(s -> new Winner[s]);
Winner youngest = lis[0];
Winner oldest = lis[lis.length - 1];
Arrays.stream(lis).forEach(System.out::println);
System.out.println("youngest: " + youngest + " oldest: " + oldest);
long finishTime = System.nanoTime();
long timeWinner = finishTime - startTime;
System.out.println("timeWinner: " + timeWinner);
comparison(Stream.of(timeWinner));
return m1;
}
public static Stream<String> multiAwardedPerson(Stream<Winner> m){
long startTime = System.nanoTime();
Comparator<Winner> comprator = Comparator.comparing(Winner -> Winner.getWinnerName());
Map<String,List<Winner>> c1 = m.collect(Collectors.groupingBy(Winner::getWinnerName));
//, Collectors.counting()));
long finishTime = System.nanoTime();
long timePerson = finishTime - startTime;
System.out.println("timePerson: " + timePerson);
comparison(Stream.of(timePerson));
return c1.values().stream().filter(s -> s.size()>= 2).map(e -> e.get(0)).sorted(comprator).map(f -> f.getWinnerName());
}
public static Stream<String> multiAwardedFilm(Stream<Winner> d){
long startTime = System.nanoTime();
Comparator<Winner> comprator = Comparator.comparing(Winner -> Winner.getYear());
Map<Integer,List<Winner>> c1 = d.collect(Collectors.groupingBy(Winner::getYear));
long finishTime = System.nanoTime();
long timeFilm = finishTime - startTime;
System.out.println(" timeFilm: " + timeFilm);
comparison(Stream.of(timeFilm));
return c1.values().stream().filter(f -> f.size() == 2).map(t -> t.get(0)).sorted(comprator).map(y -> y.getFilmTitle());
}
public static <T, U> long measure(Function<Stream<T>,Stream<U>> f , Stream<T> s1){
long startTime = System.nanoTime();
Stream<U> s2 = f.apply(s1);
List<U> collect = s2.collect(Collectors.toList());
long endTime = System.nanoTime();
long time = endTime - startTime;
return time;
}
public static long[] comparison(Stream<Winner> e){
long [] arrayTime = LongStream.of(e).toArray();
return null;
}
/**
* @param args the command line arguments
* @throws java.io.FileNotFoundException
*/
public static void main(String[] args) throws FileNotFoundException {
String[] fileName = {"G:\\path\\oscar_age_female.csv" , "G:\\path\\oscar_age_male.csv"};
// TODO code application logic here
Stream<Winner> loadData = loadData(fileName);
//loadData.forEach(x -> System.out.println(x));
// Stream<Winner> young = youngWinners(loadData);
// young.forEach(a -> System.out.println(a));
Stream<Winner> mix1 = extreamWinners(loadData);
Stream<String> winner = multiAwardedPerson(loadData);
//winner.forEach(q -> System.out.println(q));
Stream<String> date = multiAwardedFilm(loadData);
//date.forEach(l -> System.out.println(l));
}
@Override
public int getYear() {
return getYear;
}
@Override
public int getWinnerAge() {
return getWinnerAge;
}
@Override
public String getWinnerName() {
return getWinnerName;
}
@Override
public String getFilmTitle() {
return getFilmTitle;
}
}
請張貼[mcve]和錯誤的正確描述。 – khelwood
[如何計算Java程序執行速度]（https://stackoverflow.com/questions/2572868/how-to-time-java-program-execution-speed） –
我執行了我的方法的時間，但我不知道我怎麼能把這個時間傳遞給比較方法，並把它們放在從[2]到[5]的長陣列中，並且返回數組 – user8903246