java - 流已被操作或关闭，尝试创建赛车手时获得异常

Question

我有以下类(class):

public List<Racer> createListOfRacers() throws IOException {
    Stream<String> abbreviationsOfRacers = fileLoader.createStreamFromFile("src/main/resources/abbreviations.txt");

    Stream<Racer> racerList = abbreviationsOfRacers
            .map(this::createRacer);

    return racerList.collect(toList());
}

在这一行抛出异常:

.map(this::createRacer);

创建包含在同一类中的 Racer 的方法:

private Racer createRacer(String line) {
    return new Racer(extractAbbreviationOfTheRacer(line), extractNameOfTheRacer(line), extractTeamOfTheRacer(line));
}

private String extractNameOfTheRacer(String line) {
    return line.substring(line.indexOf('_') + 1, line.lastIndexOf('_'));
}

private String extractTeamOfTheRacer(String line) {
    return line.substring(line.lastIndexOf('_') + 1);
}

private String extractAbbreviationOfTheRacer(String line) {
    return line.substring(0, line.indexOf('_'));
}

赛车类:

public class Racer {

    private String abbrevition;
    private String name;
    private String team;
    private String result;


    public Racer(String abbrevition, String name, String team) {
        this.abbrevition = abbrevition;
        this.name = name;
        this.team = team;
    }

    public Racer() {
    }

Abbreviations.txt 文件:

DRR_Daniel Ricciardo_RED BULL RACING TAG HEUER
SVF_Sebastian Vettel_FERRARI
LHM_Lewis Hamilton_MERCEDES
KRF_Kimi Raikkonen_FERRARI ...

文件加载器类:

public Stream<String> createStreamFromFile(String file) throws IOException {

    try (Stream<String> streamFromFile = Files.lines(Paths.get(file))) {

        return streamFromFile;
    }

}

我阅读了有关 Stream 供应商的信息，但我无法弄清楚，因此如果您能帮助我修复我的程序，我将不胜感激。

Answer 1

您正在使用 try-with-resources创建流的语句。因此，当该方法返回时，流将被关闭，这违背了您的目的。

来自上述资源( 重点矿 )

The try-with-resources statement is a try statement that declares one or more resources. A resource is an object that must be closed after the program is finished with it. The try-with-resources statement ensures that each resource is closed at the end of the statement. Any object that implements java.lang.AutoCloseable, which includes all objects which implement java.io.Closeable, can be used as a resource.

一个 Stream扩展 BaseStream扩展 AutoCloseable
更改您的代码以返回流

public Stream<String> createStreamFromFile(String file) throws IOException {
    return Files.lines(Paths.get(file));
}