在 Java 中使用 Minim 库。无法让助手 class 工作

Question

我在 JAVA 中使用 Minim 2.2.0 库。该库要求我们定义一个 helper class 来定义两个方法，并将此 class 的对象传递给 Minim 构造函数。我写了 MinimHelper class 如下。

public class MinimHelper {
    String sketchPath( String fileName ) {
        return "C:\Users\Martin\Downloads\"+fileName;
    }

    InputStream createInput(String fileName) {
        InputStream is = null;
        try{
            is = new FileInputStream(sketchPath(fileName));
        }
        catch(Exception e){
            System.out.println(e.toString());
        }
        return is;
    }
}

而我的主要写法如下

public class Main {
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        AudioPlayer player;
        Minim minim = new Minim (new MinimHelper());
        player = minim.loadFile("Butterfly.mp3");
        player.play();
    }
}

但是，我在控制台中收到以下错误。

==== JavaSound Minim Error ====
==== Couldn't find a sketchPath method on the file loading object provided!
==== File recording will be disabled.

==== JavaSound Minim Error ====
==== Couldn't find a createInput method in the file loading object provided!
==== File loading will be disabled.

==== JavaSound Minim Error ====
==== Error invoking createInput on the file loader object: null

Exception in thread "main" java.lang.NullPointerException
    at ddf.minim.javasound.JSMinim.getAudioRecordingStream(Unknown Source)
    at ddf.minim.Minim.loadFile(Unknown Source)
    at ddf.minim.Minim.loadFile(Unknown Source)
    at Main.main(Main.java:9)

请告诉我哪里做错了。

Answer 1

我认为 sketchPath() 和 createInput() 函数需要 public 才能让 Minim 找到它们。

正在经历 the source, Minim eventually calls Class.getMethod() to get the functions you've defined. From the Java API（强调我的）：

Returns a Method object that reflects the specified public member method of the class or interface represented by this Class object.

如果这不是问题所在：确保 Butterfly.mp3 文件在您指定的位置。

C:\Users\Martin\Downloads\Butterfly.mp3存在吗？它是否具有正确的权限？

有关更多信息，您可以尝试在 MinimHelper class 中添加打印语句。函数被调用了吗？传递给它的值是什么？

在 Java 中使用 Minim 库。无法让助手 class 工作

Using Minim library in Java. Couldn't get the helper class working

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