android中可绘制图像的Java.lang.NullPointerException

我试图显示一个可绘制的图像，通过该图像（获取图像URL）从webservice动态加载

这是我的密码

protected void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);

    setContentView(R.layout.property_image_adapter);
    Intent intent=getIntent();

    Gallery propertyImageGallery=(Gallery)findViewById(R.id.gallery1);
    intent.getStringExtra("PropertyID");

    PropertyImagesList ImageList=new PropertyImagesList();
    img=ImageList.fetchPropertyImages(intent.getStringExtra("PropertyID"));

    for(int i=0;i<=img.size()-1;i++){

        try {
            Images[i]=drawableFromUrl(img.get(i).Source);//Here I am trying to save the url to the Images variable(eg: www.gggg.com/aa.jpg"). Don't know if this is correct.
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }       
    ImageAdapter=new PropertyImageAdapter(this,Images);
    propertyImageGallery.setAdapter(ImageAdapter);      
}

@SuppressWarnings("deprecation")
public static Drawable drawableFromUrl(String url) throws IOException {
    Bitmap x;

    HttpURLConnection connection = (HttpURLConnection) new URL("SOME URL APPENDING"+url.trim()).openConnection();
    connection.connect();
    InputStream input = connection.getInputStream();
    x = BitmapFactory.decodeStream(input);
    return new BitmapDrawable(x);
}
}

这是布局文件

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:gravity="center"
>

 <Gallery
    android:id="@+id/gallery1"
    android:layout_height="wrap_content"
    android:layout_width="match_parent"
    android:spacing="10dip"
    >
 </Gallery>
</LinearLayout>

请帮我找出异常的原因

这是从Web url将图像加载到Gallery的正确方法吗。 如果在我的代码中发现任何错误的实现，请更正

---

感谢您的帮助！！谢谢

您应该调用drawableFromUrl（）方法，而不是从UI线程调用。 查找此文档：

我建议您使用UniversalImageLoader从internet加载图像，查看该库，您不需要实现自己的下载程序

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:gravity="center"
>

 <Gallery
    android:id="@+id/gallery1"
    android:layout_height="wrap_content"
    android:layout_width="match_parent"
    android:spacing="10dip"
    >
 </Gallery>
</LinearLayout>

06-19 13:34:29.921: E/AndroidRuntime(16365): FATAL EXCEPTION: main
06-19 13:34:29.921: E/AndroidRuntime(16365): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.bu/com.bu.PropertySearchTypes.PropertyImageGallery}: java.lang.NullPointerException
06-19 13:34:29.921: E/AndroidRuntime(16365):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1651)
06-19 13:34:29.921: E/AndroidRuntime(16365):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1667)
06-19 13:34:29.921: E/AndroidRuntime(16365):    at android.app.ActivityThread.access$1500(ActivityThread.java:117)
06-19 13:34:29.921: E/AndroidRuntime(16365):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:935)
06-19 13:34:29.921: E/AndroidRuntime(16365):    at android.os.Handler.dispatchMessage(Handler.java:99)
06-19 13:34:29.921: E/AndroidRuntime(16365):    at android.os.Looper.loop(Looper.java:130)
06-19 13:34:29.921: E/AndroidRuntime(16365):    at android.app.ActivityThread.main(ActivityThread.java:3687)
06-19 13:34:29.921: E/AndroidRuntime(16365):    at java.lang.reflect.Method.invokeNative(Native Method)
06-19 13:34:29.921: E/AndroidRuntime(16365):    at java.lang.reflect.Method.invoke(Method.java:507)
06-19 13:34:29.921: E/AndroidRuntime(16365):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867)
06-19 13:34:29.921: E/AndroidRuntime(16365):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:625)
06-19 13:34:29.921: E/AndroidRuntime(16365):    at dalvik.system.NativeStart.main(Native Method)
06-19 13:34:29.921: E/AndroidRuntime(16365): Caused by: java.lang.NullPointerException
06-19 13:34:29.921: E/AndroidRuntime(16365):    at com.bu.PropertySearchTypes.PropertyImageGallery.onCreate(PropertyImageGallery.java:47)
06-19 13:34:29.921: E/AndroidRuntime(16365):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
06-19 13:34:29.921: E/AndroidRuntime(16365):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1615)