Java如何创建一个接受两个列表类型的方法，而不是同时

Question

I have this piece of code

public void write(LinkedList<Drug> list, String file) {
    try (FileOutputStream fs = new FileOutputStream(System.getProperty("user.dir") + "\\res\\" + file + ".dat"); ObjectOutputStream os = new ObjectOutputStream(fs)) {
        System.out.println("Writing File...");
        os.writeObject(list);
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
}

what I want is to use the same method to write a file of a different object for example

LinkedList<String> temp = new LinkedList<>();
temp.add("Something");
temp.add("Something else");
write(temp, "stringlist");

and I don't want to just make a second method which will be

public void writeSomething(LinkedList<String> list, String file) {
    try (FileOutputStream fs = new FileOutputStream(System.getProperty("user.dir") + "\\res\\" + file + ".dat"); ObjectOutputStream os = new ObjectOutputStream(fs)) {
        System.out.println("Writing File...");
        os.writeObject(list);
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
}

Answer 1

如果您的方法没有使用列表中存储的对象类型，那么您可以将方法声明如下：

public void writeSomething(LinkedList<?> list, String file)

Answer 2

To answer your question literally as stated - to allow the method to accept exactly 2 list types - have two methods which call a private generic method:

public void writeDrugs(LinkedList<Drug> list, String file) {
  writeGeneric(list, file);
}

public void writeStrings(LinkedList<String> list, String file) {
  writeGeneric(list, file);
}

private void writeGeneric(LinkedList<?> list, String file) {
  // Implementation here.
}

Note that your two public methods would need to be named differently, as otherwise they would have the same erasure.

Of course, if you don't care about it being just these two types, you can simply make the writeGeneric (or whatever your want to call it) method public .