從多個URL檢索和解析JSON並將其添加到listview

Question

我一周前開始學習android，並決定為網站bhooka.in編寫一個簡單的android應用程序。 我使用koush / ion api從URL檢索json數據。

問題出在這里-我有一個JSON文件，其中包含多個JSON URL。 現在，我嘗試在for循環中檢索所有JSON，但這似乎不起作用。 這是代碼：

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());
                                    }
                                });*/
                    }
                }
            });
}

該應用程序打開，然后凍結。 我還嘗試了使用回調的異步方法，但是它只在列表視圖中顯示一兩個條目，然后崩潰。 有人可以告訴我我在做什么錯嗎？

非常感謝。

編輯：根據建議，這是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)

Answer 1

而是使用翻新和傑克遜轉換器來獲取位置。 因為代碼非常復雜，所以它實際上只是您的代碼。 這些是處理網址的最佳組合

Answer 2

當您要將項目添加到ListView / adapter時，必須在主線程中執行此操作。 您可以為此使用處理程序：

在您的主線程中

Handler handler = new Handler();

當您需要在主線程上執行某些操作時

handler.post(new Runnable() {
    @Override
    public void run() {
        placeArrayAdapter.add(temp.get("loc_info").getAsJsonObject());
    }
}