java.util.hashmap$values 无法在 android putExtra 方法中转换为 java.io.serialized

Question

我正在尝试将自定义对象的集合传递给 android 中的服务。

try {
    FileParser parser = new FileParserImpl();
    Collection<SensorReading<Long, Float>> collection = parser.parse(fileContents);
    Intent intent = new Intent(FileBrowserActivity.this, DataService.class);

    intent.putExtra(PARAM_SENSOR_DATA, (Serializable)collection);  //exception here.
    startService(intent);
catch (Exception e) {   //e = null, 
    Log.e(TAG, "We go an exception", e);
}

我在代码中标记的行处收到异常，并且相应的 catch block 获取值为 null。为了获取该消息，我在出现异常的行执行了强制单步执行，它会将我带到类ClassCastException，我在 Debug模式下看到此消息:java.util.hashmap$values 无法转换为 java.io.serialized。我遵循了here给出的建议

还将对象作为intent.putExtra(PARAM_SENSOR_DATA, collection)传递会给出编译错误，并显示消息无法解析方法

SensorReading是一个如下所示的接口(interface):

public interface SensorReading<X, Y> {
    String getSensorIdentifier();
    List<Pair<X, Y>> getReadings();
    void addReading(Pair<X, Y> reading);
}

SensorReadings 是实现:

public class SensorReadings implements SensorReading<Long, Float>, Serializable {
    private static final long serialVersionUID = -2518143671167959230L;
    String location;
    String sensorName;

    public SensorReadings(String location, String sensorName) {
        //constructor
    }

    List<Pair<Long, Float>> timeStampReadingTuple;

    public void addReading(Pair<Long, Float> pair) {
        timeStampReadingTuple.add(pair);
    }

    public List<Pair<Long, Float>> getReadings() {
        return timeStampReadingTuple;
    }

    @Override
    public String getSensorIdentifier() {
        return sensorName + "@ " + location;
    }

    private void readObject(java.io.ObjectInputStream in) throws IOException, ClassNotFoundException {
        in.defaultReadObject();
        location = (String) in.readObject();
        sensorName = (String) in.readObject();
        int size = (int) in.readObject();
        timeStampReadingTuple = Lists.newArrayListWithCapacity(size);
        for(int i=0; i<size; ++i) {
            long timeStamp = (long) in.readObject();
            float reading = (float) in.readObject();
            timeStampReadingTuple.add(new Pair<Long, Float>(timeStamp, reading));
        }
    }

    private void writeObject(java.io.ObjectOutputStream out) throws IOException {
        out.defaultWriteObject();
        out.writeObject(location);
        out.writeObject(sensorName);
        out.writeObject(timeStampReadingTuple.size());
        for(Pair<Long, Float> pair : timeStampReadingTuple) {
            out.writeObject(pair.first);
            out.writeObject(pair.second);
        }
    }
}

Answer 1

我认为问题在于......

抛出 ClassCastException 表示代码试图将一个对象转换为它不是实例的子类。您正在尝试将 Collection 强制转换为可序列化，但 Collection 本身并未实现可序列化。

如果 DataService(您想要通过 Intent 启动的服务)是一个内部类，您可能希望将集合存储在父类的临时属性中，并在服务中使用检索它，例如

 ParentClass.this.collection