java - 为什么我无法在 Android 应用程序中的任何位置调用静态方法

Question

每当我这样做时，无论我从哪里调用它，应用程序都会崩溃并显示IllegalStateException:无法执行 Activity 的方法。我目前只有几个类，它们都在同一个包中，包括具有导致崩溃的静态方法的类。

在 Android 应用程序中调用静态方法时是否需要考虑一些问题或特殊注意事项？

public class MainActivity extends Activity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main_activity);
    ImageManager.initImageManager(this);  // crash
}

编辑
抱歉，该错误实际上是一个VerifyError。似乎与 Dropbox API 存在一些冲突，我在其中一个静态方法中使用该 API，但在应用程序崩溃之前不会调用该 API。以下是我将 ImageManager 更改为完全静态类后的错误输出，我认为它应该是这样。 ImageManager代码如下:

01-09 19:23:51.356: W/dalvikvm(32032): VFY: unable to find class referenced in signature (Lcom/dropbox/client2/DropboxAPI;)
01-09 19:23:51.357: I/dalvikvm(32032): Could not find method com.dropbox.client2.DropboxAPI.getFile, referenced from method rfynes.moviebrowser.ImageManager.downloadImage
01-09 19:23:51.357: W/dalvikvm(32032): VFY: unable to resolve virtual method 5140: Lcom/dropbox/client2/DropboxAPI;.getFile (Ljava/lang/String;Ljava/lang/String;Ljava/io/OutputStream;Lcom/dropbox/client2/ProgressListener;)Lcom/dropbox/client2/DropboxAPI$DropboxFileInfo;
01-09 19:23:51.357: D/dalvikvm(32032): VFY: replacing opcode 0x6e at 0x0063
01-09 19:23:51.358: W/dalvikvm(32032): VFY: unable to resolve exception class 735 (Lcom/dropbox/client2/exception/DropboxServerException;)
01-09 19:23:51.358: W/dalvikvm(32032): VFY: unable to find exception handler at addr 0x8b
01-09 19:23:51.358: W/dalvikvm(32032): VFY:  rejected Lrfynes/moviebrowser/ImageManager;.downloadImage (Ljava/lang/String;Ljava/io/File;Ljava/lang/String;Lcom/dropbox/client2/DropboxAPI;)V
01-09 19:23:51.358: W/dalvikvm(32032): VFY:  rejecting opcode 0x0d at 0x008b
01-09 19:23:51.358: W/dalvikvm(32032): VFY:  rejected Lrfynes/moviebrowser/ImageManager;.downloadImage (Ljava/lang/String;Ljava/io/File;Ljava/lang/String;Lcom/dropbox/client2/DropboxAPI;)V
01-09 19:23:51.358: W/dalvikvm(32032): Verifier rejected class Lrfynes/moviebrowser/ImageManager;
01-09 19:23:51.358: D/AndroidRuntime(32032): Shutting down VM
01-09 19:23:51.358: W/dalvikvm(32032): threadid=1: thread exiting with uncaught exception (group=0x41672898)
01-09 19:23:51.361: E/AndroidRuntime(32032): FATAL EXCEPTION: main
01-09 19:23:51.361: E/AndroidRuntime(32032): java.lang.VerifyError: rfynes/moviebrowser/ImageManager
01-09 19:23:51.361: E/AndroidRuntime(32032):    at rfynes.moviebrowser.MainActivity.onCreate(MainActivity.java:16)
01-09 19:23:51.361: E/AndroidRuntime(32032):    at android.app.Activity.performCreate(Activity.java:5150)
01-09 19:23:51.361: E/AndroidRuntime(32032):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
01-09 19:23:51.361: E/AndroidRuntime(32032):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2192)
01-09 19:23:51.361: E/AndroidRuntime(32032):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2288)
01-09 19:23:51.361: E/AndroidRuntime(32032):    at android.app.ActivityThread.access$600(ActivityThread.java:148)
01-09 19:23:51.361: E/AndroidRuntime(32032):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1273)
01-09 19:23:51.361: E/AndroidRuntime(32032):    at android.os.Handler.dispatchMessage(Handler.java:99)
01-09 19:23:51.361: E/AndroidRuntime(32032):    at android.os.Looper.loop(Looper.java:137)
01-09 19:23:51.361: E/AndroidRuntime(32032):    at android.app.ActivityThread.main(ActivityThread.java:5222)
01-09 19:23:51.361: E/AndroidRuntime(32032):    at java.lang.reflect.Method.invokeNative(Native Method)
01-09 19:23:51.361: E/AndroidRuntime(32032):    at java.lang.reflect.Method.invoke(Method.java:525)
01-09 19:23:51.361: E/AndroidRuntime(32032):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
01-09 19:23:51.361: E/AndroidRuntime(32032):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
01-09 19:23:51.361: E/AndroidRuntime(32032):    at dalvik.system.NativeStart.main(Native Method)

图像管理器

public class ImageManager {

private File posterDir, backdropDir;

public static void initImageManager(Activity activity) {
    posterDir = activity.getDir("poster", Context.MODE_PRIVATE);
    backdropDir = activity.getDir("backdrop", Context.MODE_PRIVATE);
}
    ...
    ...
    public static void downloadImage(String movieId, File imageDir, String imageType, DropboxAPI<AndroidAuthSession> dropbox) {
    ...
    ...

Answer 1

为了解决这个问题，我实际上最终将 ImageManager 类中的 downloadImage 方法(以及其他一些方法)分解为它们自己的单独的非静态类。 ImageManager 现在仍然是一个静态类，但它不会引起任何问题，并且应用程序不会崩溃。因此，问题似乎出在我从静态上下文中进行的 Dropbox API 调用，但我不知 Prop 体原因。不过，我对我现在所拥有的已经足够满意了。