Android 线程更新UI报错 : Can't create handler inside thread that has not called Looper.prepare()
2024-10-19 17:33:23
MainActivity中有一个按钮,绑定了save方法
public void save(View view) { String title = titleText.getText().toString(); String timelength = lengthText.getText().toString(); ExecutorService exec = Executors.newCachedThreadPool(); exec.execute(new NewsService(getApplicationContext(),title,timelength)); }
NewsService代码:
@Override public void run() { String path = "http://192.168.0.102:8080/videonews/ManageServlet"; Map<String,String> params = new HashMap<String,String>(); params.put("title",title); params.put("timelength",timelength); boolean result=false; try { result = sendGETRequest(path,params); } catch (Exception e) { e.printStackTrace(); } if(result) { Toast.makeText(context, R.string.success, Toast.LENGTH_LONG).show(); } else { Toast.makeText(context,R.string.error,Toast.LENGTH_LONG).show(); } }
报错:
04-18 13:06:36.191 2284-2305/test.example.com.newsmanage E/AndroidRuntime﹕ FATAL EXCEPTION: pool-1-thread-1 Process: test.example.com.newsmanage, PID: 2284 java.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$TN.<init>(Toast.java:336) at android.widget.Toast.<init>(Toast.java:100) at android.widget.Toast.makeText(Toast.java:250) at android.widget.Toast.makeText(Toast.java:277) at test.example.com.service.NewsService.run(NewsService.java:86) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587) at java.lang.Thread.run(Thread.java:818)
查了资料,说是Android中不能在子线程中来刷新UI。如果要实现你这功能的话。建议是在你的子线程中添加hander来发送消息更新线程。
下面这样做就OK了
1.在Activity中增加如下代码
private Handler myHandler = new Handler() { @Override public void handleMessage(Message msg) { switch (msg.what) { case 0x00 : Toast.makeText(getApplicationContext(),"save success",Toast.LENGTH_SHORT).show(); break; default: Toast.makeText(getApplicationContext(),"save fail",Toast.LENGTH_SHORT).show(); } } };
2.启动线程时,将handler传入:
exec.execute(new NewsService(getApplicationContext(),myHandler,title,timelength));
3.在线程中,发送消息给handler:
@Override public void run() { String path = "http://192.168.0.102:8080/videonews/ManageServlet"; Map<String,String> params = new HashMap<String,String>(); params.put("title",title); params.put("timelength",timelength); boolean result=false; try { result = sendGETRequest(path,params); } catch (Exception e) { e.printStackTrace(); } Message msg = new Message(); if(result) msg.what = 0x00; else msg.what = 0x01; handler.sendMessage(msg); }
完成。
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