如何从衍生的后台服务访问原始活动的视图 [英] How to access original activity's views from spawned background service

问题描述

我有一个名为 A 的活动，在选择菜单项 0 时，它会生成服务 B，该服务在新线程中启动一个可运行的 C.我在活动 A 中有一个 TextView，我想在线程 C 中访问它.

I have an activity called A, and on the selection of menu item 0, it spawns service B, which starts a runnable C in a new thread. I have a TextView in activity A, which I want to access in thread C.

我尝试将 TextView 设为公共静态字段，但这会产生以下错误:

I've tried making the TextView a public static field, but that generates the following error:

07-21 07:26:25.723: ERROR/AndroidRuntime(1975): android.view.ViewRoot$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.
07-21 07:26:25.723: ERROR/AndroidRuntime(1975):     at android.view.ViewRoot.checkThread(ViewRoot.java:2440)
07-21 07:26:25.723: ERROR/AndroidRuntime(1975):     at android.view.ViewRoot.invalidateChild(ViewRoot.java:522)
07-21 07:26:25.723: ERROR/AndroidRuntime(1975):     at android.view.ViewRoot.invalidateChildInParent(ViewRoot.java:540)
07-21 07:26:25.723: ERROR/AndroidRuntime(1975):     at android.view.ViewGroup.invalidateChild(ViewGroup.java:2332)
07-21 07:26:25.723: ERROR/AndroidRuntime(1975):     at android.view.View.invalidate(View.java:4437)
07-21 07:26:25.723: ERROR/AndroidRuntime(1975):     at android.widget.TextView.updateAfterEdit(TextView.java:4593)
07-21 07:26:25.723: ERROR/AndroidRuntime(1975):     at android.widget.TextView.handleTextChanged(TextView.java:5932)
07-21 07:26:25.723: ERROR/AndroidRuntime(1975):     at android.widget.TextView$ChangeWatcher.onTextChanged(TextView.java:6081)
07-21 07:26:25.723: ERROR/AndroidRuntime(1975):     at android.text.SpannableStringBuilder.sendTextChange(SpannableStringBuilder.java:889)
07-21 07:26:25.723: ERROR/AndroidRuntime(1975):     at android.text.SpannableStringBuilder.change(SpannableStringBuilder.java:352)
07-21 07:26:25.723: ERROR/AndroidRuntime(1975):     at android.text.SpannableStringBuilder.change(SpannableStringBuilder.java:269)
07-21 07:26:25.723: ERROR/AndroidRuntime(1975):     at android.text.SpannableStringBuilder.replace(SpannableStringBuilder.java:432)
07-21 07:26:25.723: ERROR/AndroidRuntime(1975):     at android.text.SpannableStringBuilder.append(SpannableStringBuilder.java:259)
07-21 07:26:25.723: ERROR/AndroidRuntime(1975):     at android.text.SpannableStringBuilder.append(SpannableStringBuilder.java:28)
07-21 07:26:25.723: ERROR/AndroidRuntime(1975):     at android.widget.TextView.append(TextView.java:2191)
07-21 07:26:25.723: ERROR/AndroidRuntime(1975):     at android.widget.TextView.append(TextView.java:2178)
07-21 07:26:25.723: ERROR/AndroidRuntime(1975):     at com.android.peekaboo.DoScan$scanBody.run(DoScan.java:36)
07-21 07:26:25.723: ERROR/AndroidRuntime(1975):     at java.lang.Thread.run(Thread.java:1058)

我也考虑过尝试通过意图传递视图，但不知道这将如何工作.我需要什么来完成这项工作?

I have also considered trying to pass the View through an intent, but do not know how that would work. What do I need to make this work?

推荐答案

您必须从 GUI 线程更新小部件，也就是创建视图层次结构的线程".执行此操作的标准方法是通过 Handlers 和如何使用处理程序的示例可以在 中找到ProgressDialog 示例(展开'Example ProgressDialog with a second thread').

You have to update widgets from the GUI thread, aka 'the thread that created the view hierarchy'. The standard way to do this is via Handlers and an example of how to use handlers can be found in the ProgressDialog Example (expand 'Example ProgressDialog with a second thread').

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