在Android Studio中反编译scala的.class文件会生成.java文件？

Question

As first thing, I don't know Scala so well and neither .class files in details (from both java and scala).

I'm porting Apache Flink on Android. One of the libraries used in the project is flink-runtime.jar and contains this Scala file:

runtime/minicluster/LocalFlinkMiniCluster.scala

When Intellij IDEA decompile the LocalFlinkMiniCluster.class contained the .jar file, the correct and origal LocalFlinkMiniCluster.scala is displayed.

This doesn't happen in Android studio. Instead a java code is returned with the message :

Decompiled .class file, bytecode version: 50.0 (Java 6)

To make you understand better what I'm talking about, this is the method setMemory from the original .scala file:

  def setMemory(config: Configuration): Unit = {
    // set this only if no memory was pre-configured
    if (config.getInteger(ConfigConstants.TASK_MANAGER_MEMORY_SIZE_KEY, -1) == -1) {

      val bufferSize: Int = config.getInteger(
        ConfigConstants.TASK_MANAGER_MEMORY_SEGMENT_SIZE_KEY,
        ConfigConstants.DEFAULT_TASK_MANAGER_MEMORY_SEGMENT_SIZE)

      val bufferMem: Long = config.getLong(
        ConfigConstants.TASK_MANAGER_NETWORK_NUM_BUFFERS_KEY,
        ConfigConstants.DEFAULT_TASK_MANAGER_NETWORK_NUM_BUFFERS) * bufferSize.toLong

      val numTaskManager = config.getInteger(
        ConfigConstants.LOCAL_NUMBER_TASK_MANAGER,
        ConfigConstants.DEFAULT_LOCAL_NUMBER_TASK_MANAGER)

      val memoryFraction = config.getFloat(
        ConfigConstants.TASK_MANAGER_MEMORY_FRACTION_KEY,
        ConfigConstants.DEFAULT_MEMORY_MANAGER_MEMORY_FRACTION)

      // full memory size
      var memorySize: Long = EnvironmentInformation.getSizeOfFreeHeapMemoryWithDefrag

      // compute the memory size per task manager. we assume equally much memory for
      // each TaskManagers and each JobManager
      memorySize /= numTaskManager + 1 // the +1 is the job manager

      // for each TaskManager, subtract the memory needed for memory buffers
      memorySize -= bufferMem
      memorySize = (memorySize * memoryFraction).toLong
      memorySize >>>= 20 // bytes to megabytes
      config.setLong(ConfigConstants.TASK_MANAGER_MEMORY_SIZE_KEY, memorySize)
    }
  }

This is the java version created by Android Studio (what the hell is that asian symbol?):

public void setMemory(Configuration config) {
    if(config.getInteger("taskmanager.memory.size", -1) == -1) {
        int bufferSize = config.getInteger("taskmanager.memory.segment-size", '耀');
        long bufferMem = config.getLong("taskmanager.network.numberOfBuffers", 2048L) * (long)bufferSize;
        int numTaskManager = config.getInteger("local.number-taskmanager", 1);
        float memoryFraction = config.getFloat("taskmanager.memory.fraction", 0.7F);
        long memorySize = EnvironmentInformation.getSizeOfFreeHeapMemoryWithDefrag();
        memorySize /= (long)(numTaskManager + 1);
        memorySize -= bufferMem;
        memorySize = (long)((float)((double)memorySize * (double)memoryFraction));
        memorySize >>>= 20;
        config.setLong("taskmanager.memory.size", memorySize);
    }

}

And obviously the execution of the two methods have different effects.

Please, can you help me to understand why this happens and how can I resolve this problem? Thanks.

Answer 1

I found out the problem by myself: the Scala plugin is installed by default (or there is an option anyway in the wizard) on IntelliJ. In Android Studio instead it has to be installed manually.