如何将 Scala 特征转换为 Java 类？

Question

我尝试将一些 Scala 源代码转换为 Java 源代码。但我面临一些麻烦。以下是 Scala 源代码。trait Reader {  def read(name: String): String = {    //some codes are here.....  }}trait FileInputBase {  def getFormat(path: String): String = {    //some codes are here.....  }}case class FileStreamInput(name: String, path: String) extends Reader with FileInputBase {  def read(name: String): String = {    //some codes are here.....  }  var format = getFormat("joseph") }我将这些 Scala 代码转换为 Java 源代码，如下所示，class Reader {  public String read(String name) {    // some java codes are here  }}interface FileInputBase {  public String getFormat(String path) {    // some java codes are here  }}我做了java类public class FileStreamInput extends Reader implements FileInputBase {  ....}但这些Java代码根本不起作用。我是 Scala 语言的初学者。

Answer 1

你可以尝试这样的事情：

public interface Reader {

  default String read(String name) {

    return "reading from " + name;

  }

}

public interface FileInputBase {

  default String getFormat(String path) {

    return "Format of " + path;

  }

}

public class FileStreamInput implements Reader, FileInputBase {

  private String path;

  private String name;

  public FileStreamInput(String path, String name) {

    super();

    this.path = path;

    this.name = name;

  }

  public String read(String name) {

    return "FileStreamInput: reading from " + name;

  }

  public String getPath() {

    return path;

  }

  public void setPath(String path) {

    this.path = path;

  }

  public String getName() {

    return name;

  }

  public void setName(String name) {

    this.name = name;

  }

  public String getFormat() {

    return getFormat(path);

  }

  public static void main(String[] args) {

    FileStreamInput input = new FileStreamInput("Alice", "/home/alice");

    System.out.println("format: " + input.getFormat());

  }

}