ScalaでAndroidアプリ作成時、AsyncTaskの可変長引数メソッドが使えないことへの対策とサンプル

AsyncTask1.java

package jp.ponko2.android.os;

import android.os.AsyncTask;

public abstract class AsyncTask1<Params, Progress, Result> extends AsyncTask<Params, Progress, Result> {
   @Override
   protected Result doInBackground(Params... params) {
      return doInBackground(params.length > 0 ? params[0] : null);
   }

   abstract protected Result doInBackground(Params param);

   @Override
   protected void onProgressUpdate(Progress... values) {
      onProgressUpdate(values.length > 0 ? values[0] : null);
   }

   protected void onProgressUpdate(Progress value) {
   }

   @SuppressWarnings({"unchecked"})
   protected final void publishProgress(Progress value) {
      super.publishProgress(value);
   }
}

SampleActivity.scala

package jp.ponko2.android.sample

import _root_.android.app.Activity
import _root_.android.os.Bundle
import _root_.android.os.AsyncTask.Status
import _root_.android.widget.{TextView, Toast}
import _root_.android.view.Window

import jp.ponko2.android.os.AsyncTask1

class SampleActivity extends Activity {
  private lazy val mTask = new TestTask

  override def onCreate(savedInstanceState: Bundle) {
    super.onCreate(savedInstanceState)

    val values = Seq(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)

    setupProgress()

    setContentView(new TextView(this) {
      setText(values.mkString(" + ") + " = ")
    })

    mTask.execute(values)
  }

  override protected def onDestroy() {
    super.onDestroy()

    if (mTask.getStatus == Status.RUNNING) {
      mTask cancel true
    }
  }

  private def setupProgress() {
    requestWindowFeature(Window.FEATURE_PROGRESS)
    requestWindowFeature(Window.FEATURE_INDETERMINATE_PROGRESS)
  }

  private class TestTask extends AsyncTask1[Seq[Int], Int, Int] {
    override protected def onPreExecute() = showProgress()

    override protected def doInBackground(values: Seq[Int]): Int = {
      val count = values.length
      var total = 0
      for (i <- 0 until count) {
        publishProgress(((i / count.toFloat) * 10000).toInt)
        Thread.sleep(500)
        total += values(i)
      }
      total
    }

    override protected def onProgressUpdate(progress: Int) {
      setProgress(progress)
    }

    override protected def onPostExecute(result: Int) {
      hideProgress()
      Toast.makeText(SampleActivity.this, result.toString, Toast.LENGTH_LONG).show()
    }

    private def showProgress() = {
      setProgressBarVisibility(true)
      setProgressBarIndeterminateVisibility(true)
    }

    private def hideProgress() = {
      setProgressBarVisibility(false)
      setProgressBarIndeterminateVisibility(false)
    }
  }
}