java - Byte[] 和 java.lang.OutOfMemoryError 按位读/写文件

Question

我正致力于清除 android 中的一些可用空间。这是我的代码:

private void creatingFileDelete(int size, int passMode) 
    {
        File lastFile = new File(Environment.getExternalStorageDirectory().getAbsolutePath(),"/.tmpToDelete/last.txt");
        if (lastFile.exists() == false) 
        {
        try 
        {
            lastFile.createNewFile();
        }//End of try block
        catch (IOException e) 
        {
            e.printStackTrace();
        }//End of catch block
    }//End of if condition

    try 
    {
        RandomAccessFile rwFile = new RandomAccessFile(lastFile, "rw");
        rwFile.setLength(1024*1024*size);
        FileChannel rwChannel = rwFile.getChannel();
        int numBytes = (int) rwChannel.size();
        MappedByteBuffer buffer = rwChannel.map(FileChannel.MapMode.READ_WRITE, 0, numBytes);
        buffer.clear();
        byte[] randomBytes = new byte[numBytes];

        new Random().nextBytes(randomBytes);
        Arrays.fill(randomBytes, 0, randomBytes.length, (byte) passMode);
        buffer.put(randomBytes);

        buffer.force();
        rwFile.close();
    }//End of try block
    catch (Exception e) 
    {
        Log.e("Clean free space---","message :" +e.getMessage());
    }//End of catch block
}//End of creatingFileDelete 

在删除过程中，我遇到了以下崩溃。

java.lang.RuntimeException: An error occured while executing doInBackground()
          at android.os.AsyncTask$3.done(AsyncTask.java:299)
          at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:352)
          at java.util.concurrent.FutureTask.setException(FutureTask.java:219)
          at java.util.concurrent.FutureTask.run(FutureTask.java:239)
          at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
          at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080)
          at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573)
          at java.lang.Thread.run(Thread.java:856)
    Caused by: java.lang.OutOfMemoryError
          at xxx.creatingFileDelete(CleanFreespace.java:2634)
          at xxx.CleanFreespace.access$71(CleanFreespace.java:2610)
          at xxx.CleanFreespace$15.doInBackground(CleanFreespace.java:2100)
          at xxx.CleanFreespace$15.doInBackground(CleanFreespace.java:1)
          at android.os.AsyncTask$2.call(AsyncTask.java:287)
          at java.util.concurrent.FutureTask.run(FutureTask.java:234)
          ... 4 more

friend ，我该如何解决这个问题。

Answer 1

OutOfMemoryError 

Thrown when a request for memory is made that can not be satisfied using the available platform resources. Such a request may be made by both the running application or by an internal function of the VM(Virtual Machine)

当你得到类似 OutOfMemory 的错误时这意味着您的应用程序内存不足，因为您的应用程序消耗了更多空间然后由系统分配给它。

把这个属性android:largeHeap="true"在 <application/>开始manifest.xml文件

例如

 <application
    android:name="support.classes.StartUp"
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:largeHeap="true" // you are increasing the heap space for the app 
    android:theme="@style/AppThemeTest">

如果你只是想释放一些空间，最好让最了解的 Android 系统来处理它

System.gc()

在执行任何内存消耗任务之前调用垃圾收集器，因为这将为您释放一些空间。如果您尝试在完成任务后调用它，那么它没有任何用处