运行出错 #2

01-17 10:43:59.194 29701-30457/com.example.mjj.selectphotodemo E/AndroidRuntime: FATAL EXCEPTION: pool-2-thread-1
Process: com.example.mjj.selectphotodemo, PID: 29701
java.lang.NullPointerException: Attempt to invoke virtual method 'boolean android.graphics.Bitmap.compress(android.graphics.Bitmap$CompressFormat, int, java.io.OutputStream)' on a null object reference
at com.example.mjj.selectphotodemo.utils.ImageLoader.cacheBitmap2Disk(ImageLoader.java:314)
at com.example.mjj.selectphotodemo.utils.ImageLoader.access$1300(ImageLoader.java:32)
at com.example.mjj.selectphotodemo.utils.ImageLoader$DiskCacheThread.run(ImageLoader.java:285)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1113)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:588)
at java.lang.Thread.run(Thread.java:818)