为什么无法在 Android 中打开自定义寻呼机适配器内部的 activity？

Question

我是 Android 应用程序的开发者。在我的应用程序中，我正在使用寻呼机适配器创建自定义图像寻呼机。我想要的是当我点击寻呼机的当前图像时，我想启动图像activity。所以我尝试启动 activity 内部适配器。除了启动 activity，我的寻呼机工作正常。但是当我开始 activity 时，它会抛出错误。我该如何解决？

这是我的寻呼机适配器以及我如何在其中启动 activity：

public class ItemImagePager extends PagerAdapter{
    Context mContext;
    LayoutInflater mLayoutInflater;

    ArrayList<String> mResources;

    public ItemImagePager(Context context,ArrayList<String> urls) {
        mContext = context;
        mLayoutInflater = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        mResources = urls;
    }

    @Override
    public int getCount() {
        return mResources.size();
    }

    @Override
    public boolean isViewFromObject(View view, Object object) {
        return view == ((LinearLayout) object);
    }

    @Override
    public Object instantiateItem(ViewGroup container, final int position) {
        View itemView = mLayoutInflater.inflate(R.layout.item_image_pager_item, container, false);

        ImageView imageView = (ImageView) itemView.findViewById(R.id.image_view_item_image_pager);
        Picasso.with(mContext).load(mResources.get(position)).into(imageView);
        imageView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent i = new Intent(mContext, ViewImageActivity.class);
                i.putExtra("url",mResources.get(position));
                mContext.startActivity(i);
            }
        });

        container.addView(itemView);

        return itemView;
    }

    @Override
    public void destroyItem(ViewGroup container, int position, Object object) {
        container.removeView((LinearLayout) object);
    }
}

这是我开始activity点击图片时的logcat：

04-10 11:05:37.698 28934-28934/com.blog.waiyanhein.mmfashion.mmfashion W/EGL_genymotion: eglSurfaceAttrib not implemented
04-10 11:05:37.742 28934-28934/com.blog.waiyanhein.mmfashion.mmfashion W/EGL_genymotion: eglSurfaceAttrib not implemented
04-10 11:05:38.938 28934-28934/com.blog.waiyanhein.mmfashion.mmfashion D/AndroidRuntime: Shutting down VM
04-10 11:05:38.938 28934-28934/com.blog.waiyanhein.mmfashion.mmfashion W/dalvikvm: threadid=1: thread exiting with uncaught exception (group=0xa6184908)
04-10 11:05:38.938 28934-28934/com.blog.waiyanhein.mmfashion.mmfashion E/AndroidRuntime: FATAL EXCEPTION: main
04-10 11:05:38.938 28934-28934/com.blog.waiyanhein.mmfashion.mmfashion E/AndroidRuntime: android.util.AndroidRuntimeException: Calling startActivity() from outside of an Activity  context requires the FLAG_ACTIVITY_NEW_TASK flag. Is this really what you want?
04-10 11:05:38.938 28934-28934/com.blog.waiyanhein.mmfashion.mmfashion E/AndroidRuntime:     at android.app.ContextImpl.startActivity(ContextImpl.java:952)
04-10 11:05:38.938 28934-28934/com.blog.waiyanhein.mmfashion.mmfashion E/AndroidRuntime:     at android.app.ContextImpl.startActivity(ContextImpl.java:939)
04-10 11:05:38.938 28934-28934/com.blog.waiyanhein.mmfashion.mmfashion E/AndroidRuntime:     at com.blog.waiyanhein.mmfashion.model.ItemImagePager.onClick(ItemImagePager.java:54)
04-10 11:05:38.938 28934-28934/com.blog.waiyanhein.mmfashion.mmfashion E/AndroidRuntime:     at android.view.View.performClick(View.java:4204)
04-10 11:05:38.938 28934-28934/com.blog.waiyanhein.mmfashion.mmfashion E/AndroidRuntime:     at android.view.View$PerformClick.run(View.java:17355)
04-10 11:05:38.938 28934-28934/com.blog.waiyanhein.mmfashion.mmfashion E/AndroidRuntime:     at android.os.Handler.handleCallback(Handler.java:725)
04-10 11:05:38.938 28934-28934/com.blog.waiyanhein.mmfashion.mmfashion E/AndroidRuntime:     at android.os.Handler.dispatchMessage(Handler.java:92)
04-10 11:05:38.938 28934-28934/com.blog.waiyanhein.mmfashion.mmfashion E/AndroidRuntime:     at android.os.Looper.loop(Looper.java:137)
04-10 11:05:38.938 28934-28934/com.blog.waiyanhein.mmfashion.mmfashion E/AndroidRuntime:     at android.app.ActivityThread.main(ActivityThread.java:5041)
04-10 11:05:38.938 28934-28934/com.blog.waiyanhein.mmfashion.mmfashion E/AndroidRuntime:     at java.lang.reflect.Method.invokeNative(Native Method)
04-10 11:05:38.938 28934-28934/com.blog.waiyanhein.mmfashion.mmfashion E/AndroidRuntime:     at java.lang.reflect.Method.invoke(Method.java:511)
04-10 11:05:38.938 28934-28934/com.blog.waiyanhein.mmfashion.mmfashion E/AndroidRuntime:     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
04-10 11:05:38.938 28934-28934/com.blog.waiyanhein.mmfashion.mmfashion E/AndroidRuntime:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
04-10 11:05:38.938 28934-28934/com.blog.waiyanhein.mmfashion.mmfashion E/AndroidRuntime:     at dalvik.system.NativeStart.main(Native Method)

Answer 1

向您的意图添加 - FLAG_ACTIVITY_NEW_TASK 标记：

myIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);

或者您应该尝试添加标志：

myIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);

Answer 2

mContext 显然不是 Activity。它应该是，就像您应该通过在 Activity 上调用 getLayoutInflater() 来获得 mLayoutInflater 一样，因此您的主题得到尊重。 ~~而且，由于您没有实现任何普通的 View 构造函数，很明显您是创建 ItemImagePager 实例的人，而不是框架（例如，通过膨胀一些布局）。~~

那么，您的选择是：

更改创建 ItemImagePager 的代码以传入 Activity 作为第一个参数（理想情况下，修复 LayoutManager 位），或者
阅读错误消息并完全按照它告诉您的去做：将 FLAG_ACTIVITY_NEW_TASK 添加到 Intent

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