由于刚学android,碰到一问题,本人想实现的功能是请求一个URL,返回一个JSON串, 然后将JSON解析成集合对象,将集合数据填充到ListView,取数据生成集合这个过程都没有问题,但是将数据填充到UI组件时有问题,下面是部分源码:
public class MainActivity extends AppCompatActivity { ListView listView; Context txContext; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); txContext = this; listView = (ListView)findViewById(R.id.listView); // new Thread(new Runnable() { @Override public void run() { //get NetWorkdata List<News> news = NewsDataUtil.getNewsForNetWork(); System.out.println("======================getDataCount:" + news.size()+""); Message message = Message.obtain(); message.obj = news; handler.handleMessage(message); } }).start(); } private Handler handler = new Handler(){ @Override public void handleMessage(Message msg) { List<News> news = (List<News>) msg.obj; //Update UI if (news!=null && news.size()>0)//set Adapter listView.setAdapter(new NewsListViewAdapter(txContext, news)); } }; }
图片使用的是在线程中请求网络数据, 将数据存放在Message中,并通过handler对象handleMessage。
在handler的handleMessage中更新UI,执行后出现错误:
10-13 03:29:03.275 24742-24761/? E/AndroidRuntime: FATAL EXCEPTION: Thread-165 Process: com.example.rookie.listviewjson, PID: 24742 android.view.ViewRootImpl$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views. at android.view.ViewRootImpl.checkThread(ViewRootImpl.java:6556) at android.view.ViewRootImpl.focusableViewAvailable(ViewRootImpl.java:3034) at android.view.ViewGroup.focusableViewAvailable(ViewGroup.java:761) at android.view.ViewGroup.focusableViewAvailable(ViewGroup.java:761) at android.view.ViewGroup.focusableViewAvailable(ViewGroup.java:761) at android.view.ViewGroup.focusableViewAvailable(ViewGroup.java:761) at android.view.ViewGroup.focusableViewAvailable(ViewGroup.java:761) at android.view.ViewGroup.focusableViewAvailable(ViewGroup.java:761) at android.view.View.setFlags(View.java:10555) at android.view.View.setFocusableInTouchMode(View.java:7502) at android.widget.AdapterView.checkFocus(AdapterView.java:737) at android.widget.ListView.setAdapter(ListView.java:492) at com.example.rookie.listviewjson.MainActivity$2.handleMessage(MainActivity.java:47) at com.example.rookie.listviewjson.MainActivity$1.run(MainActivity.java:36) at java.lang.Thread.run(Thread.java:818) 10-13 03:29:03.577 24742-24764/? E/Surface: getSlotFromBufferLocked: unknown buffer: 0xaa043730
不知道问题出在哪里,有知道的帮忙解释下,谢谢!
解决方案
40
在完成网络操作后,调用handler的sendMessage之类的方法将Message发送,这样才是正确的,然后在handler的handler的handleMessage方法中处理Message。这样发送Message的话,Handler内部的机制才会把Message的处理传到handler所在的线程,你写的也就是主线程,而你直接调用handleMessage方法,那么handleMessage就是在非主线程内部调用的,listview就在非主线程中设置adapter了