奇怪ANR中的StringBuilder

-1

從Android開發者控制檯

DALVIK THREADS: 
(mutexes: tll=0 tsl=0 tscl=0 ghl=0 hwl=0 hwll=0) 
"main" prio=5 tid=1 SUSPENDED 
    | group="main" sCount=1 dsCount=0 obj=0x40022198 self=0xcec8 
    | sysTid=15809 nice=0 sched=0/0 cgrp=[fopen-error:2] handle=-1345006496 
    | schedstat=(105169616659 16803131154 25724) 
    at java.lang.String._getChars(String.java:~1041) 
    at java.lang.AbstractStringBuilder.<init>(AbstractStringBuilder.java:89) 
    at java.lang.StringBuilder.<init>(StringBuilder.java:96) 
    at org.nkuznetsov.onlineradio.FavoriteList.save(FavoriteList.java:37) 
    at org.nkuznetsov.onlineradio.FavoriteList.add(FavoriteList.java:60) 
    at org.nkuznetsov.onlineradio.RadioActivity$OnFavoriteChangeListener.onCheckedChanged(RadioActivity.java:289) 
    at android.widget.CompoundButton.setChecked(CompoundButton.java:124) 
    at android.widget.CompoundButton.toggle(CompoundButton.java:86) 
    at android.widget.CompoundButton.performClick(CompoundButton.java:98) 
    at android.view.View$PerformClick.run(View.java:9080) 
    at android.os.Handler.handleCallback(Handler.java:587) 
    at android.os.Handler.dispatchMessage(Handler.java:92) 
    at android.os.Looper.loop(Looper.java:130) 
    at android.app.ActivityThread.main(ActivityThread.java:3687) 
    at java.lang.reflect.Method.invokeNative(Native Method) 
    at java.lang.reflect.Method.invoke(Method.java:507) 
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:625) 
    at dalvik.system.NativeStart.main(Native Method) 

"Binder Thread #3" prio=5 tid=9 NATIVE 
    | group="main" sCount=1 dsCount=0 obj=0x40526f60 self=0x194808 
    | sysTid=15817 nice=0 sched=0/0 cgrp=[fopen-error:2] handle=1788936 
    | schedstat=(2014164 15899659 17) 
    at dalvik.system.NativeStart.run(Native Method) 

"AsyncTask #1" prio=5 tid=8 WAIT 
    | group="main" sCount=1 dsCount=0 obj=0x40524388 self=0x19d380 
    | sysTid=15816 nice=10 sched=0/0 cgrp=[fopen-error:2] handle=1693616 
    | schedstat=(1090911877 313018788 393) 
    at java.lang.Object.wait(Native Method) 
    - waiting on <0x40524560> (a java.lang.VMThread) 
    at java.lang.Thread.parkFor(Thread.java:1424) 
    at java.lang.LangAccessImpl.parkFor(LangAccessImpl.java:48) 
    at sun.misc.Unsafe.park(Unsafe.java:337) 
    at java.util.concurrent.locks.LockSupport.park(LockSupport.java:157) 
    at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2016) 
    at java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:411) 
    at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1021) 
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1081) 
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:581) 
    at java.lang.Thread.run(Thread.java:1019) 

"Binder Thread #2" prio=5 tid=7 NATIVE 
    | group="main" sCount=1 dsCount=0 obj=0x405150e0 self=0x15eed8 
    | sysTid=15815 nice=0 sched=0/0 cgrp=[fopen-error:2] handle=1413168 
    | schedstat=(2929685 26489259 22) 
    at dalvik.system.NativeStart.run(Native Method) 

"Binder Thread #1" prio=5 tid=6 NATIVE 
    | group="main" sCount=1 dsCount=0 obj=0x40514aa8 self=0x16bad8 
    | sysTid=15814 nice=0 sched=0/0 cgrp=[fopen-error:2] handle=1159936 
    | schedstat=(5920410 23956299 25) 
    at dalvik.system.NativeStart.run(Native Method) 

"Compiler" daemon prio=5 tid=5 VMWAIT 
    | group="system" sCount=1 dsCount=0 obj=0x405110a0 self=0x16b9a0 
    | sysTid=15813 nice=0 sched=0/0 cgrp=[fopen-error:2] handle=1239400 
    | schedstat=(207977297 25329589 821) 
    at dalvik.system.NativeStart.run(Native Method) 

"Signal Catcher" daemon prio=5 tid=4 RUNNABLE 
    | group="system" sCount=0 dsCount=0 obj=0x40510fe0 self=0x12e7a8 
    | sysTid=15812 nice=0 sched=0/0 cgrp=[fopen-error:2] handle=1238888 
    | schedstat=(5798340 8666992 14) 
    at dalvik.system.NativeStart.run(Native Method) 

"GC" daemon prio=5 tid=3 VMWAIT 
    | group="system" sCount=1 dsCount=0 obj=0x40510f38 self=0x178360 
    | sysTid=15811 nice=0 sched=0/0 cgrp=[fopen-error:2] handle=1413104 
    | schedstat=(139343257 133178717 75) 
    at dalvik.system.NativeStart.run(Native Method) 

"HeapWorker" daemon prio=5 tid=2 SUSPENDED 
    | group="system" sCount=1 dsCount=0 obj=0x40510e80 self=0x178228 
    | sysTid=15810 nice=0 sched=0/0 cgrp=[fopen-error:2] handle=1160864 
    | schedstat=(612121568 1730712888 15455) 
    at dalvik.system.NativeStart.run(Native Method)

據我明白在主線程存在於org.nkuznetsov.onlineradio.FavoriteList.save問題（FavoriteList.java:37）方法。

In FavoriteList.save（）我只是從字符串集合連接字符串並將ti寫入共享首選項。 FavoriteList類的

來源是在這裏：https://code.google.com/p/android-online-radio/source/browse/trunk/src/org/nkuznetsov/onlineradio/FavoriteList.java

爲什麼ANR出現一段時間嗎？

來源

2012-08-04 Nik

如果它給你一個ANR這是你不等待完成的方法做它在另一個線程：

private static void save(final Vector<String> favorites) 
    { 

     new Thread() 
      public void run(){ 
       String tmpFav = new String(); 

       if (favorites.size() > 0) 
       { 
        tmpFav = String.valueOf(favorites.get(0)); 

        for (int i = 1; i < favorites.size(); i++) 
        { 
          tmpFav += FAVORITES_SEPARATOR; 
          tmpFav += favorites.get(i); 
        } 
       } 

       SharedPreferences.Editor editor = preferences.edit(); 

       if (tmpFav.equals(new String())) editor.remove(FAVORITES_KEY); 
       else editor.putString(FAVORITES_KEY, tmpFav); 

       editor.commit(); 
      } 
     }.start(); 
    }

你只需要記住保存可能尚未完成，當你下次訪問其他方法。

如果它是一個字符串矢量你不需要問的字符串值：

tmpFav = favorites.get(0);

另外檢查是否字符串爲空就是這樣一點更清晰：

if ("".equals(tmpFav)) editor.remove(FAVORITES_KEY)

我也會使用StringBuilder而不是串聯。

StringBuilder b = new StringBuilder(); 
    b.append(FAVOURITES_SEPARATOR); 
    b.append(favorites.get(i); 
    String tmpFav = b.toString();

如果你去的線程選項要小心，你可能想看看Java Synchonized methods

來源

2012-08-04 09:46:48 Blundell

奇怪ANR中的StringBuilder

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