Android 应用程序崩溃数据库答案

【问题标题】：Android App Crashes DatabaseAndroid 应用程序崩溃数据库
【发布时间】：2014-12-30 18:06:51
【问题描述】：

我和我的朋友正在尝试开发一个与数据库交互的应用程序，基本上是添加从购物车中删除项目。我猜我们的应用程序的数据库连接有问题。

目前，我们实际上是在使用以下教程来使用 php 和 mysql 开发应用程序： http://www.androidhive.info/2012/05/how-to-connect-android-with-php-mysql/

我正在托管来自 000webhost.com 的文件，上面有 php 文件和一个名为“Products”的数据库，用于从应用程序发送数据。

我们所做的一切都与教程中的说明相同，但我提到的不是 php 文件应用程序中的 url，而是来自文件所在的 000webhost.com 的域名。但是，应用程序崩溃并退出。尝试了几个 url，甚至从 localhost (XAMP)，我们仍然一无所知。

提前感谢您对此问题的任何建议和解决方案！

谢谢！

下面是我运行应用程序后从 Eclipse 得到的 logcat：

    11-03 18:21:25.790: E/JSON Parser(917): Error parsing data org.json.JSONException: Value <br><table of type java.lang.String cannot be converted to JSONObject
11-03 18:21:25.950: E/AndroidRuntime(917): FATAL EXCEPTION: AsyncTask #1
11-03 18:21:25.950: E/AndroidRuntime(917): Process: com.example.database, PID: 917
11-03 18:21:25.950: E/AndroidRuntime(917): java.lang.RuntimeException: An error occured while executing doInBackground()
11-03 18:21:25.950: E/AndroidRuntime(917):  at android.os.AsyncTask$3.done(AsyncTask.java:300)
11-03 18:21:25.950: E/AndroidRuntime(917):  at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:355)
11-03 18:21:25.950: E/AndroidRuntime(917):  at java.util.concurrent.FutureTask.setException(FutureTask.java:222)
11-03 18:21:25.950: E/AndroidRuntime(917):  at java.util.concurrent.FutureTask.run(FutureTask.java:242)
11-03 18:21:25.950: E/AndroidRuntime(917):  at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
11-03 18:21:25.950: E/AndroidRuntime(917):  at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
11-03 18:21:25.950: E/AndroidRuntime(917):  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
11-03 18:21:25.950: E/AndroidRuntime(917):  at java.lang.Thread.run(Thread.java:841)
11-03 18:21:25.950: E/AndroidRuntime(917): Caused by: java.lang.NullPointerException
11-03 18:21:25.950: E/AndroidRuntime(917):  at com.example.database.AllProductsActivity$LoadAllProducts.doInBackground(AllProductsActivity.java:130)
11-03 18:21:25.950: E/AndroidRuntime(917):  at com.example.database.AllProductsActivity$LoadAllProducts.doInBackground(AllProductsActivity.java:1)
11-03 18:21:25.950: E/AndroidRuntime(917):  at android.os.AsyncTask$2.call(AsyncTask.java:288)
11-03 18:21:25.950: E/AndroidRuntime(917):  at java.util.concurrent.FutureTask.run(FutureTask.java:237)
11-03 18:21:25.950: E/AndroidRuntime(917):  ... 4 more
11-03 18:21:31.810: E/WindowManager(917): android.view.WindowLeaked: Activity com.example.database.AllProductsActivity has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView{b4de64a0 V.E..... R.....ID 0,0-383,96} that was originally added here
11-03 18:21:31.810: E/WindowManager(917):   at android.view.ViewRootImpl.<init>(ViewRootImpl.java:348)
11-03 18:21:31.810: E/WindowManager(917):   at android.view.WindowManagerGlobal.addView(WindowManagerGlobal.java:248)
11-03 18:21:31.810: E/WindowManager(917):   at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:69)
11-03 18:21:31.810: E/WindowManager(917):   at android.app.Dialog.show(Dialog.java:286)
11-03 18:21:31.810: E/WindowManager(917):   at com.example.database.AllProductsActivity$LoadAllProducts.onPreExecute(AllProductsActivity.java:117)
11-03 18:21:31.810: E/WindowManager(917):   at android.os.AsyncTask.executeOnExecutor(AsyncTask.java:587)
11-03 18:21:31.810: E/WindowManager(917):   at android.os.AsyncTask.execute(AsyncTask.java:535)
11-03 18:21:31.810: E/WindowManager(917):   at com.example.database.AllProductsActivity.onCreate(AllProductsActivity.java:57)
11-03 18:21:31.810: E/WindowManager(917):   at android.app.Activity.performCreate(Activity.java:5231)
11-03 18:21:31.810: E/WindowManager(917):   at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
11-03 18:21:31.810: E/WindowManager(917):   at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)
11-03 18:21:31.810: E/WindowManager(917):   at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
11-03 18:21:31.810: E/WindowManager(917):   at android.app.ActivityThread.access$800(ActivityThread.java:135)
11-03 18:21:31.810: E/WindowManager(917):   at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
11-03 18:21:31.810: E/WindowManager(917):   at android.os.Handler.dispatchMessage(Handler.java:102)
11-03 18:21:31.810: E/WindowManager(917):   at android.os.Looper.loop(Looper.java:136)
11-03 18:21:31.810: E/WindowManager(917):   at android.app.ActivityThread.main(ActivityThread.java:5017)
11-03 18:21:31.810: E/WindowManager(917):   at java.lang.reflect.Method.invokeNative(Native Method)
11-03 18:21:31.810: E/WindowManager(917):   at java.lang.reflect.Method.invoke(Method.java:515)
11-03 18:21:31.810: E/WindowManager(917):   at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
11-03 18:21:31.810: E/WindowManager(917):   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
11-03 18:21:31.810: E/WindowManager(917):   at dalvik.system.NativeStart.main(Native Method)

【问题讨论】：

标签： java android mysql database phpmyadmin

【解决方案1】：

您的 Web API 响应有问题

查看错误日志说明

>  11-03 18:21:25.790: E/JSON Parser(917): Error parsing data
> org.json.JSONException: Value <br><table of type java.lang.String
> cannot be converted to JSONObject

现在，由于您没有从 URL 中获取正确的 JSON， JSONObject json 变得空，然后代码进一步下降并抛出空指针异常（根据您提供的 url 中的示例代码）

int success = json.getInt(TAG_SUCCESS);

与之对应的日志也给出了行号。你可以在你的代码中仔细检查它（AllProductsActivity.java line num 130）

11-03 18:21:25.950: E/AndroidRuntime(917): 由: java.lang.NullPointerException 11-03 18:21:25.950: E/AndroidRuntime(917)：在 com.example.database.AllProductsActivity$LoadAllProducts.doInBackground(AllProductsActivity.java:130)

【讨论】：