java.lang.RuntimeException: Can't create handler inside thread that has not

在子线程中调用了这句：

Toast.makeText(UiUtils.getContext(), "正在下载"+name, Toast.LENGTH_SHORT).show();

报出了下面的错误

08-15 14:52:50.368 3517-3560/com.ldw.marketm E/AndroidRuntime: FATAL EXCEPTION: pool-2-thread-5Process: com.ldw.marketm, PID: 3517java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()at android.os.Handler.<init>(Handler.java:200)at android.os.Handler.<init>(Handler.java:114)at android.widget.Toast$TN.<init>(Toast.java:327)at android.widget.Toast.<init>(Toast.java:92)at android.widget.Toast.makeText(Toast.java:241)at com.ldw.marketm.holder.DetailBottomHolder$2.run(DetailBottomHolder.java:78)at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)at java.lang.Thread.run(Thread.java:841)

分析：跟踪源码

查看makeText方法，可以看到 new了一个Toast实例

public static Toast makeText(Context context, CharSequence text,@Duration int duration) {Toast result = new Toast(context);LayoutInflater inflate = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);View v = inflate.inflate(com.android.internal.R.layout.transient_notification, null);TextView tv = (TextView) v.findViewById(com.android.internal.R.id.message);tv.setText(text);result.mNextView = v;result.mDuration = duration;return result;
}

Toast构造函数中又实例化了一个 TN对象

public Toast(Context context) {mContext = context;mTN = new TN();mTN.mY = context.getResources().getDimensionPixelSize(com.android.internal.R.dimen.toast_y_offset);mTN.mGravity = context.getResources().getInteger(com.android.internal.R.integer.config_toastDefaultGravity);
}

在静态类TN中，可以读到这一句：

final Handler mHandler = new Handler();

创建了一个Handler对象

private static class TN extends ITransientNotification.Stub {final Runnable mShow = new Runnable() {@Overridepublic void run() {handleShow();}};final Runnable mHide = new Runnable() {@Overridepublic void run() {handleHide();// Don't do this in handleHide() because it is also invoked by handleShow()mNextView = null;}};private final WindowManager.LayoutParams mParams = new WindowManager.LayoutParams();final Handler mHandler = new Handler();

读 Handler构造函数：

/*** * Default constructor associates this handler with the {@link Looper} for* the * current thread. * * If this thread does not have a looper, this* handler won't be able to receive messages * so an exception is thrown.*/
public Handler() {this(null, false);
}

继续后面

public Handler(Callback callback, boolean async) {if (FIND_POTENTIAL_LEAKS) {final Class<? extends Handler> klass = getClass();if ((klass.isAnonymousClass() || klass.isMemberClass() || klass.isLocalClass())&& (klass.getModifiers() & Modifier.STATIC) == 0) {Log.w(TAG,"The following Handler class should be static or leaks might occur: "+ klass.getCanonicalName());}}mLooper = Looper.myLooper();if (mLooper == null) {throw new RuntimeException("Can't create handler inside thread that has not called Looper.prepare()");}mQueue = mLooper.mQueue;mCallback = callback;mAsynchronous = async;
}

主线程中创建handler后会默认创建一个looper对象。但是子线程不会，需要手动创建。其ThreadLoacl中没有设置过Looper，mLooper==null ,所以会抛出异常。

解决方法

方法一：增加Looper.prepare();

ThreadManager.getInstance().createLongPool().execute(new Runnable(){@Overridepublic void run() {//SystemClock.sleep(3000);Looper.prepare();Toast.makeText(UiUtils.getContext(), "正在下载"+name, Toast.LENGTH_SHORT).show();Looper.loop();// 进入loop中的循环，查看消息队列/*getActivity().runOnUiThread(new Runnable() {@Overridepublic void run() {}});*/}});

方法二：post 给主线程去处理

// if current thread is background thread
// post show-toast-runnable to main handler
// if current thread is background thread
// post show-toast-runnable to main handlermainHandler.post(new Runnable() {@Overridepublic void run() {if (toast == null) {toast = Toast.makeText(context, "",     Toast.LENGTH_SHORT);}toast.setText(msg);toast.setDuration(Toast.LENGTH_SHORT);toast.show();}
});

java.lang.RuntimeException: Can't create handler inside thread that has not相关推荐

java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()
java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare() ...
Android --- java.lang.RuntimeException: Can‘t create handler inside thread that has not called Loop
报错信息如下: java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.pr ...
Can't create handler inside thread that has not called Looper.prepare() 解决办法
在开发的过程当中,遇到了想在一个线程中弹出一个提示窗 new AlertDialog.Builder( context),但是就出现了一个问题. java.lang.Runtim ...
Can't create handler inside thread that has not called Looper.prepare()
问题: Can't create handler inside thread that has not called Looper.prepare() 1,在报错的方法前加Looper.prepare ...
MQ java.lang.OutOfMemoryError: unable to create new native thread
文章目录 1. 问题现象 2. 分析定位 3. 解决方案 4. 结果验证 5. 总结 1. 问题现象 java.lang.OutOfMemoryError: unable to create new ...
解决java.lang.OutOfMemoryError: unable to create new native thread问题
解决java.lang.OutOfMemoryError: unable to create new native thread问题参考文章: (1)解决java.lang.OutOfMemoryE ...
spark大批量读取Hbase时出现java.lang.OutOfMemoryError: unable to create new native thread
这个问题我去网上搜索了一下,发现了很多的解决方案都是增加的nproc数量,即用户最大线程数的数量,但我修改了并没有解决问题,最终是通过修改hadoop集群的最大线程数解决问题的. 并且网络上的回答多数 ...
Can't create handler inside thread Thread that has not called Looper.prepare()
今天在子线程里面写了一个Toast 运行程序直接崩溃了看了下log 如下最后忽然想到了子线程里面不能直接使用Toast 然后就添加了 Looper.prepare(); 和 Looper.loo ...
Caused by: java.lang.RuntimeException: Font asset not found fonts/SYFZLTKHJW.TTF
/*** 通过反射方法设置app全局字体*/public void setTypeface() {typeFace = Typeface.createFromAsset(getAssets(), &q ...

java.lang.RuntimeException: Can't create handler inside thread that has not

java.lang.RuntimeException: Can't create handler inside thread that has not相关推荐

最新文章

热门文章