一周前我开始学习 android，并决定为网站bhooka.in编写一个简单的 android 应用程序。我使用 koush/ion api 从 url 检索 json 数据。
这就是问题所在 - 我有一个 JSON 文件，其中包含多个 JSON URL。现在我尝试在 for 循环中检索所有 JSON，但这似乎不起作用。这是代码：
Future<JsonObject> loading;
private void load() {
// don't attempt to load more if a load is already in progress
if (loading != null && !loading.isDone() && !loading.isCancelled())
return;
// load the tweets
String url = "http://bhooka.in/web_services_json_helper.php?mode=fetch_locations&user_agent=in.bhooka.bhooka&city_id=4";
loading = Ion.with(this)
.load(url)
.asJsonObject()
.setCallback(new FutureCallback<JsonObject>() {
@Override
public void onCompleted(Exception e, JsonObject result) {
// this is called back onto the ui thread, no Activity.runOnUiThread or Handler.post necessary.
if (e != null) {
Toast.makeText(getView().getContext(), "Error loading information", Toast.LENGTH_LONG).show();
return;
}
JsonArray locationsList = result.getAsJsonArray("locations");
// add the tweets
for (int i = 0; i < locationsList.size(); i++) {
try {
JsonObject temp = Ion.with(getView().getContext())
.load("http://bhooka.in/web_services_json_helper.php?mode=fetch_loc_info&user_agent=in.bhooka.bhooka&loc_id=" + locationsList.get(i).getAsJsonObject().get("post_id").getAsString())
.asJsonObject().get();
placeArrayAdapter.add(temp.get("loc_info").getAsJsonObject());
}
catch (Exception ex)
{
ex.printStackTrace();
}
/* tried this approach - but it doesn't work
.setCallback(new FutureCallback<JsonObject>() {
@Override
public void onCompleted(Exception e, JsonObject result) {
// this is called back onto the ui thread, no Activity.runOnUiThread or Handler.post necessary.
if (e != null) {
Toast.makeText(getView().getContext(), "Error loading information", Toast.LENGTH_LONG).show();
return;
}
placeArrayAdapter.add(result.get("loc_info").getAsJsonObject());
}
});*/
}
}
});
}
该应用程序打开，然后只是冻结。我也尝试过使用回调的异步方法，但它只在列表视图中显示一两个条目，然后崩溃。有人可以告诉我我做错了什么吗？
非常感谢。
编辑：正如建议的，这里是logcat：
07-14 17:02:11.851 20332-20332/? D/dalvikvm﹕ Late-enabling CheckJNI
07-14 17:02:11.867 20332-20338/? D/dalvikvm﹕ Debugger has detached; object registry had 1 entries
07-14 17:02:12.206 20332-20332/? I/Adreno-EGL﹕ <qeglDrvAPI_eglInitialize:410>: EGL 1.4 QUALCOMM build: AU_LINUX_ANDROID_LNX.LA.3.5.1_RB1.04.04.02.048.018_msm8610_LNX.LA.3.5.1_RB1__release_AU ()
OpenGL ES Shader Compiler Version: E031.24.00.08
Build Date: 03/07/14 Fri
Local Branch:
Remote Branch: quic/LNX.LA.3.5.1_RB1.1
Local Patches: NONE
Reconstruct Branch: AU_LINUX_ANDROID_LNX.LA.3.5.1_RB1.04.04.02.048.018 + f2fd134 + NOTHING
07-14 17:02:12.244 20332-20332/? D/OpenGLRenderer﹕ Enabling debug mode 0
07-14 17:02:14.469 20332-20364/in.bhooka.bhooka D/dalvikvm﹕ Trying to load lib /data/app-lib/in.bhooka.bhooka-2/libgmscore.so 0x41d995f0
07-14 17:02:14.470 20332-20364/in.bhooka.bhooka E/dalvikvm﹕ dlopen("/data/app-lib/in.bhooka.bhooka-2/libgmscore.so") failed: dlopen failed: library "/data/app-lib/in.bhooka.bhooka-2/libgmscore.so" not found
07-14 17:02:14.470 20332-20364/in.bhooka.bhooka E/ProviderInstaller﹕ Unable to load native code from /data/app-lib/in.bhooka.bhooka-2/libgmscore.so
07-14 17:02:14.470 20332-20364/in.bhooka.bhooka D/dalvikvm﹕ Trying to load lib /data/app-lib/com.google.android.gms-2/libgmscore.so 0x41d995f0
07-14 17:02:14.472 20332-20364/in.bhooka.bhooka D/dalvikvm﹕ Added shared lib /data/app-lib/com.google.android.gms-2/libgmscore.so 0x41d995f0
07-14 17:02:14.472 20332-20364/in.bhooka.bhooka D/dalvikvm﹕ No JNI_OnLoad found in /data/app-lib/com.google.android.gms-2/libgmscore.so 0x41d995f0, skipping init
07-14 17:02:14.474 20332-20364/in.bhooka.bhooka E/ProviderInstaller﹕ libgmscore version mismatch (0 vs. 7574)
07-14 17:02:14.474 20332-20364/in.bhooka.bhooka W/IonConscrypt﹕ Conscrypt initialization failed.
07-14 17:02:44.955 20332-20364/in.bhooka.bhooka D/dalvikvm﹕ GC_FOR_ALLOC freed 3066K, 29% free 7930K/11072K, paused 37ms, total 47ms
07-14 17:02:45.008 20332-20332/in.bhooka.bhooka D/AndroidRuntime﹕ Shutting down VM
07-14 17:02:45.008 20332-20332/in.bhooka.bhooka W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0x415dad40)
07-14 17:02:45.010 20332-20332/in.bhooka.bhooka E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: in.bhooka.bhooka, PID: 20332
java.lang.NullPointerException
at in.bhooka.bhooka.MainActivity$1.onCompleted(MainActivity.java:73)
at in.bhooka.bhooka.MainActivity$1.onCompleted(MainActivity.java:67)
at com.koushikdutta.async.future.SimpleFuture.handleCallbackUnlocked(SimpleFuture.java:107)
at com.koushikdutta.async.future.SimpleFuture.setComplete(SimpleFuture.java:141)
at com.koushikdutta.async.future.SimpleFuture.setComplete(SimpleFuture.java:124)
at com.koushikdutta.ion.IonRequestBuilder$1.run(IonRequestBuilder.java:244)
at com.koushikdutta.async.AsyncServer$RunnableWrapper.run(AsyncServer.java:57)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5086)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
at dalvik.system.NativeStart.main(Native Method)