在Xamarin上编写Android应用程序。
出现此错误
[MonoDroid] UNHANDLED EXCEPTION:
[MonoDroid] System.InvalidOperationException: Operation is not valid due to the current state of the object
[MonoDroid] at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () <0x00028>
[MonoDroid] at System.Runtime.CompilerServices.AsyncMethodBuilderCore.<ThrowAsync>m__0 (object) <0x0003f>
[MonoDroid] at Android.App.SyncContext/<Post>c__AnonStorey0.<>m__0 () <0x00027>
[MonoDroid] at Java.Lang.Thread/RunnableImplementor.Run () <0x0003f>
[MonoDroid] at Java.Lang.IRunnableInvoker.n_Run (intptr,intptr) <0x0003b>
[MonoDroid] at (wrapper dynamic-method) object.abf695dd-f4ec-4a71-8e1c-73614b06354b (intptr,intptr) <0x0003b>
[AndroidRuntime] Shutting down VM
[AndroidRuntime] FATAL EXCEPTION: main
[AndroidRuntime] java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
[AndroidRuntime] at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:608)
[AndroidRuntime] at dalvik.system.NativeStart.main(Native Method)
[AndroidRuntime] Caused by: java.lang.reflect.InvocationTargetException
[AndroidRuntime] at java.lang.reflect.Method.invokeNative(Native Method)
[AndroidRuntime] at java.lang.reflect.Method.invoke(Method.java:511)
[AndroidRuntime] at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:841)
[AndroidRuntime] ... 2 more
[AndroidRuntime] Caused by: md52ce486a14f4bcd95899665e9d932190b.JavaProxyThrowable: System.InvalidOperationException: Operation is not valid due to the current state of the object
[AndroidRuntime] at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () <0x00028>
[AndroidRuntime] at System.Runtime.CompilerServices.AsyncMethodBuilderCore.<ThrowAsync>m__0 (object) <0x0003f>
[AndroidRuntime] at Android.App.SyncContext/<Post>c__AnonStorey0.<>m__0 () <0x00027>
[AndroidRuntime] at Java.Lang.Thread/RunnableImplementor.Run () <0x0003f>
[AndroidRuntime] at Java.Lang.IRunnableInvoker.n_Run (intptr,intptr) <0x0003b>
[AndroidRuntime] at (wrapper dynamic-method) object.abf695dd-f4ec-4a71-8e1c-73614b06354b (intptr,intptr) <0x0003b>
[AndroidRuntime]
[AndroidRuntime] at mono.java.lang.RunnableImplementor.n_run(Native Method)
[AndroidRuntime] at mono.java.lang.RunnableImplementor.run(RunnableImplementor.java:29)
[AndroidRuntime] at android.os.Handler.handleCallback(Handler.java:725)
[AndroidRuntime] at android.os.Handler.dispatchMessage(Handler.java:92)
[AndroidRuntime] at android.os.Looper.loop(Looper.java:153)
[AndroidRuntime] at android.app.ActivityThread.main(ActivityThread.java:5330)
我通过网址
进行解析解析器代码
string url2 = "http://new.murakami.ua/?mkapi=getProductsByCat&cat_id=182";
JsonValue json = await FetchAsync(url2);
ParseAndDisplay1(json);
ParseAndDisplay2(json);
ParseAndDisplay3(json);
private async Task<JsonValue> FetchAsync(string url2)
{
// Create an HTTP web request using the URL:
HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(new Uri(url2));
request.ContentType = "application/json";
request.Method = "GET";`
// Send the request to the server and wait for the response:
using (WebResponse response = await request.GetResponseAsync())
{
// Get a stream representation of the HTTP web response:
using (Stream stream = response.GetResponseStream())
{
// Use this stream to build a JSON document object:
JsonValue jsonDoc = await Task.Run(() => JsonObject.Load(stream));
Console.Out.WriteLine("Response: {0}", jsonDoc.ToString());
// Return the JSON document:
return jsonDoc;
}
}
}
private void ParseAndDisplay1(JsonValue json)
{
//ImageButton product = FindViewById<ImageButton>(Resource.Id.vugor);
TextView productname = FindViewById<TextView>(Resource.Id.posttittle);
TextView price = FindViewById<TextView>(Resource.Id.price);
TextView weight = FindViewById<TextView>(Resource.Id.weight);
JsonValue firstitem = json[43];
//Console.Out.WriteLine(firstitem["post_title"].ToString());
productname.Text = firstitem["post_title"];
price.Text = firstitem["price"] + " грн";
weight.Text = firstitem["weight"] + "г";
productname.Click += delegate
{
var intent485 = new Intent(this, typeof(LanchiDetails1));
StartActivity(intent485);
};
}
private void ParseAndDisplay2(JsonValue json)
{
//ImageButton product = FindViewById<ImageButton>(Resource.Id.vugor);
TextView productname = FindViewById<TextView>(Resource.Id.posttittle1);
TextView price = FindViewById<TextView>(Resource.Id.price1);
TextView weight = FindViewById<TextView>(Resource.Id.weight1);
JsonValue firstitem = json[3];
//Console.Out.WriteLine(firstitem["post_title"].ToString());
productname.Text = firstitem["post_title"];
price.Text = firstitem["price"] + " грн";
weight.Text = firstitem["weight"] + "г";
productname.Click += delegate
{
var intent486 = new Intent(this, typeof(LanchiDetails2));
StartActivity(intent486);
};
}
private void ParseAndDisplay3(JsonValue json)
{
//ImageButton product = FindViewById<ImageButton>(Resource.Id.vugor);
TextView productname = FindViewById<TextView>(Resource.Id.posttittle2);
TextView price = FindViewById<TextView>(Resource.Id.price2);
TextView weight = FindViewById<TextView>(Resource.Id.weight2);
JsonValue firstitem = json[2];
//Console.Out.WriteLine(firstitem["post_title"].ToString());
productname.Text = firstitem["post_title"];
price.Text = firstitem["price"] + " грн";
weight.Text = firstitem["weight"] + "г";
productname.Click += delegate
{
var intent487 = new Intent(this, typeof(LanchiDetails3));
StartActivity(intent487);
};
}
我尝试评论ParseAndDisplay- ParseAndDisplay3
请参阅回复
但是当我取消注释ParseAndDisplay -ParseAndDisplay3时，我有错误“应用已经停止”。
代码有什么问题？
答案 0 :(得分：0)
当您的异步任务（FetchAsync）仍在运行时，看起来正在调用ParseAndDisplay。
在你的ParseAndDisplay函数中，检查json的值，你可能会发现它是null。
在调用ParseAndDisplay之前，您需要等待FetchAsync完成。或者你可以从FetchAsync调用ParseAndDisplay
答案 1 :(得分：0)
解决方案就是：
旧API
Array
(
[43] => WP_Post Object
(
[ID] => 4378
[post_author] => 4
[post_date] => 2015-10-01 12:47:54
[post_date_gmt] => 2015-10-01 08:47:54
[post_content] =>
[post_title] => Ямато
[post_excerpt] => Курячий бульйон з яйцем / салат овочевий з заправкою насу / крохмальна локшина з овочами та свининою
[post_status] => publish
[comment_status] => open
[ping_status] => closed
[post_password] =>
[post_name] => yamato-0
[to_ping] =>
[pinged] =>
[post_modified] => 2015-10-08 14:38:18
[post_modified_gmt] => 2015-10-08 10:38:18
[post_content_filtered] =>
[post_parent] => 0
[guid] => http://new.murakami.ua/shop/yamato-0/
[menu_order] => 0
[post_type] => product
[post_mime_type] =>
[comment_count] => 0
[filter] => raw
[img_url] => http://new.murakami.ua/wp-content/uploads/YAmato.jpg
[visibility] => visible
[price] => 99.00
[weight] => 225/110/175
[energy] =>
[sku] => 172
[category] => 182
)
[3] => WP_Post Object
(
[ID] => 4377
[post_author] => 4
[post_date] => 2015-10-01 12:47:54
[post_date_gmt] => 2015-10-01 08:47:54
[post_content] =>
[post_title] => Хонсю
[post_excerpt] => Місо суп / салат овочевий з лососем / курячі крильця теріякі з сирним соусом
[post_status] => publish
[comment_status] => open
[ping_status] => closed
[post_password] =>
[post_name] => honsyu
[to_ping] =>
[pinged] =>
[post_modified] => 2015-10-08 14:37:27
[post_modified_gmt] => 2015-10-08 10:37:27
[post_content_filtered] =>
[post_parent] => 0
[guid] => http://new.murakami.ua/shop/honsyu/
[menu_order] => 0
[post_type] => product
[post_mime_type] =>
[comment_count] => 0
[filter] => raw
[img_url] => http://new.murakami.ua/wp-content/uploads/Honsyu.jpg
[visibility] => visible
[price] => 99.00
[weight] => 165/120/180/40
[energy] =>
[sku] => 156
[category] => 182
)
[4] => WP_Post Object
(
[ID] => 4237
[post_author] => 7
[post_date] => 2015-09-08 12:29:11
[post_date_gmt] => 2015-09-08 08:29:11
[post_content] =>
[post_title] => Фудзіяма
[post_excerpt] => Суп суймоно з кальмаром / салат теріякі з куркою / рол з огірком / рис смажений з грибами
[post_status] => publish
[comment_status] => open
[ping_status] => closed
[post_password] =>
[post_name] => fudziyama
[to_ping] =>
[pinged] =>
[post_modified] => 2015-10-08 14:38:51
[post_modified_gmt] => 2015-10-08 10:38:51
[post_content_filtered] =>
[post_parent] => 0
[guid] => http://new.murakami.ua/shop/fudziyama/
[menu_order] => 0
[post_type] => product
[post_mime_type] =>
[comment_count] => 0
[filter] => raw
[img_url] => http://new.murakami.ua/wp-content/uploads/Fudziyama.jpg
[visibility] => visible
[price] => 99.00
[weight] => 210/140/116/180
[energy] =>
[sku] => 471
[category] => 182
)
)
新API
Array
(
[0] => WP_Post Object
(
[ID] => 4378
[post_author] => 4
[post_date] => 2015-10-01 12:47:54
[post_date_gmt] => 2015-10-01 08:47:54
[post_content] =>
[post_title] => Ямато
[post_excerpt] => Курячий бульйон з яйцем / салат овочевий з заправкою насу / крохмальна локшина з овочами та свининою
[post_status] => publish
[comment_status] => open
[ping_status] => closed
[post_password] =>
[post_name] => yamato-0
[to_ping] =>
[pinged] =>
[post_modified] => 2015-10-08 14:38:18
[post_modified_gmt] => 2015-10-08 10:38:18
[post_content_filtered] =>
[post_parent] => 0
[guid] => http://new.murakami.ua/shop/yamato-0/
[menu_order] => 0
[post_type] => product
[post_mime_type] =>
[comment_count] => 0
[filter] => raw
[img_url] => http://new.murakami.ua/wp-content/uploads/YAmato.jpg
[visibility] => visible
[price] => 99.00
[weight] => 225/110/175
[energy] =>
[sku] => 172
[category] => 182
)
[1] => WP_Post Object
(
[ID] => 4377
[post_author] => 4
[post_date] => 2015-10-01 12:47:54
[post_date_gmt] => 2015-10-01 08:47:54
[post_content] =>
[post_title] => Хонсю
[post_excerpt] => Місо суп / салат овочевий з лососем / курячі крильця теріякі з сирним соусом
[post_status] => publish
[comment_status] => open
[ping_status] => closed
[post_password] =>
[post_name] => honsyu
[to_ping] =>
[pinged] =>
[post_modified] => 2015-10-08 14:37:27
[post_modified_gmt] => 2015-10-08 10:37:27
[post_content_filtered] =>
[post_parent] => 0
[guid] => http://new.murakami.ua/shop/honsyu/
[menu_order] => 0
[post_type] => product
[post_mime_type] =>
[comment_count] => 0
[filter] => raw
[img_url] => http://new.murakami.ua/wp-content/uploads/Honsyu.jpg
[visibility] => visible
[price] => 99.00
[weight] => 165/120/180/40
[energy] =>
[sku] => 156
[category] => 182
)
[2] => WP_Post Object
(
[ID] => 4237
[post_author] => 7
[post_date] => 2015-09-08 12:29:11
[post_date_gmt] => 2015-09-08 08:29:11
[post_content] =>
[post_title] => Фудзіяма
[post_excerpt] => Суп суймоно з кальмаром / салат теріякі з куркою / рол з огірком / рис смажений з грибами
[post_status] => publish
[comment_status] => open
[ping_status] => closed
[post_password] =>
[post_name] => fudziyama
[to_ping] =>
[pinged] =>
[post_modified] => 2015-10-08 14:38:51
[post_modified_gmt] => 2015-10-08 10:38:51
[post_content_filtered] =>
[post_parent] => 0
[guid] => http://new.murakami.ua/shop/fudziyama/
[menu_order] => 0
[post_type] => product
[post_mime_type] =>
[comment_count] => 0
[filter] => raw
[img_url] => http://new.murakami.ua/wp-content/uploads/Fudziyama.jpg
[visibility] => visible
[price] => 99.00
[weight] => 210/140/116/180
[energy] =>
[sku] => 471
[category] => 182
)
)
我们已经混乱了，感觉像物体