File.createTempFile in Java getting Incompatible type error

问题

Till now my code works fine where I am creating file in temporary directory and processing it.

But now I am trying to provide specific directory where I actually want to create xml file. So in method createTmpXmlFile

    private static Path createTmpXmlFile(final String prefix) {
        try {
            log.info("Creating temporary file {}{}", prefix, XML_SUFFIX);
            return Files.createTempFile(Paths.get(gleifZipFile), prefix, XML_SUFFIX);

        } catch (IOException e) {
            throw new IllegalStateException("Could not create tmp file at " + prefix + XML_SUFFIX + ". ", e);
        }
    }

I changed from

return Files.createTempFile(prefix, XML_SUFFIX);

to

return File.createTempFile(prefix, XML_SUFFIX, "/tmp/in");

and I get following error:

java: incompatible types: java.lang.String cannot be converted to java.io.File.

If I change the logic here then its affecting other method that are calling createTmpXmlFile method.

I really don't understand how to resolve this issue. Below is my code:

@Slf4j
public class InputCS implements Runnable {

    public static final String XML_SUFFIX = ".xml";
    
    @Value("${gleifdataimporter.file.dir}")    
    private String gleifZipFile;

    private void processleifZipFile() {
        final AtomicBoolean isInsideLeiRecord = new AtomicBoolean();
        isInsideLeiRecord.set(false);
        final StringBuilder currentLeiRecordXml = new StringBuilder();

        try (FileSystem zipFs = FileSystems.newFileSystem(jobRunner.getInputZipPath(), null)) {
            Path tmpXMLPath = xmlFileFromLeiZipFile(zipFs);

            try (Stream<String> lines = Files.lines(tmpXMLPath)) {
                AtomicInteger processedLinesCounter = new AtomicInteger();
                AtomicInteger currentLineNumber = new AtomicInteger();
                lines.sequential().forEach(handleLineAndIncrementLineNumber(isInsideLeiRecord, currentLeiRecordXml, processedLinesCounter, currentLineNumber));
                log.info("{} lines of XML file inside LEIF input ZIP file {} processed.", processedLinesCounter.get(), jobRunner.getInputZipPath());
            }catch (IOException e) {
                throw new IllegalStateException("Problem reading input file at " + jobRunner.getInputZipPath() + ".", e);
            } finally {
                Files.delete(tmpXMLPath);
            }
        } catch (IOException e) {
            throw new IllegalStateException("Problem reading input file at " + jobRunner.getInputZipPath() + ".", e);
        }
    }

    private Path xmlFileFromLeiZipFile(FileSystem zipFs) {       //extracts the xml file from zip file
        log.info("Input file {} exists: {}", jobRunner.getInputZipPath(), Files.exists(jobRunner.getInputZipPath()));
        Path tmpXmlPath = createTmpXmlFile("leif__" + System.currentTimeMillis());
        for (Path rootDir : zipFs.getRootDirectories()) {
            try (Stream<Path> files = treeAt(rootDir)) {
                log.info("Trying to extract LEIF XML file from ZIP file into {}.", tmpXmlPath);
                final Path xmlFileInsideZip = files
                        .filter(isNotADir())
                        .filter(Files::isRegularFile)
                        .findFirst()
                        .orElseThrow(() -> new IllegalStateException("No file found in LEI ZIP file."));
                log.info("Path to LEIF XML file inside ZIP file: {}.", xmlFileInsideZip);
                return copyReplacing(xmlFileInsideZip, tmpXmlPath);
            }
        }
        throw new IllegalStateException("No file found in LEI ZIP file " + jobRunner.getInputZipPath() + ".");
    }
    

    private static Path createTmpXmlFile(final String prefix) {
        try {
            log.info("Creating temporary file {}{}", prefix, XML_SUFFIX);
            return Files.createTempFile(Paths.get(gleifZipFile), prefix, XML_SUFFIX);

        } catch (IOException e) {
            throw new IllegalStateException("Could not create tmp file at " + prefix + XML_SUFFIX + ". ", e);
        }
    }
    
    @NotNull
    private static Path copyReplacing(Path from, Path to) {
        requireNonNull(from, "Trying to copy from a path, which is null to path " + to + ".");   //trying to copy file where no xml file exist in root directory
        requireNonNull(to, "Trying to copy from path " + from + " to a path, which is null.");
        try {
            return Files.copy(from, to, REPLACE_EXISTING);
        } catch (IOException e) {
            throw new IllegalStateException("Cannot copy from " + from + " to " + to + ". ", e);
        }
    }
    
}

回答1:

1. As suggested by Slaw, use Files#createTempFile(Path,String,String,FileAttribute...) to specify the directory to create temp file.
2. Use Paths#get(String,String...) for java 7 or 8, or Path#of(String,String...) for java 11 or later to convert String to Path. Further reading: Paths.get vs Path.of

---

private static Path createTmpXmlFile(final String prefix) {
    try {
        // Java 11 or later
        // return Files.createTempFile(Path.of("/tmp/in"), prefix, XML_SUFFIX);
        // Java 8
        return Files.createTempFile(Paths.get("/tmp/in"), prefix, XML_SUFFIX);
    } catch (IOException e) {
        throw new IllegalStateException("Could not create tmp file at " + prefix + XML_SUFFIX + ". ", e);
    }
}

回答2:

File.createTempFile is expecting a File object as third parameter. Just wrap your "/tmp/in" into a File => return File.createTempFile(prefix, XML_SUFFIX, new File("/tmp/in")); and you should be good to go.

so you can do:

File.createTempFile("prefix", "suffix", new File("/tmp/in"));

Or using NIO (recommended)

Files.createTempFile(Paths.get("/tmp/in"), "prefix", "suffix");

来源：https://stackoverflow.com/questions/62537379/file-createtempfile-in-java-getting-incompatible-type-error