使用listview 的时候出现如下错误：
java.lang.IllegalStateException: The content of the adapter has changed but ListView did not receive a notification. Make sure the content of your adapter is not modified from a background thread, but only from the UI thread.
检查adapter.notifyDataSetChanged();是否在主线程执行；
我遇到的情况是我在handle里面执行更新操作还是会出现上面那个错误，而且只是偶尔报错。
private Handler myHandler = new Handler(new Callback() {
@Override
public boolean handleMessage(Message msg) {
switch (msg.what) {
case Constant.MSG_SUCCESS:
if (adapter != null) {
adapter.notifyDataSetChanged();
}
break;
default:
break;
}
return false;
}
});
后来再网上查资料说handle不一定会在主线程。又改成这样：
private Handler myHandler = new Handler(new Callback() {
@Override
public boolean handleMessage(Message msg) {
switch (msg.what) {
case Constant.MSG_SUCCESS:
if (adapter != null) {
runOnUiThread(new Runnable() {
@Override
public void run() {
adapter.notifyDataSetChanged();
}
});
}
break;
default:
break;
}
return false;
}
});
还是会报错；后来想了很久发现问题原因，举个简单的例子
new Thread(new Runnable() {
@Override
public void run() {
// TODO Auto-generated method stub
for(int i = 0; i < 10; i++){
String str = “s”+i;
list.add(str);
}
myHandler.sendEmptyMessage(Constant.MSG_SUCCESS);
}
}).start();
list是adapter传递的集合数据是个全局变量。我们在子线程直接这样添加数据数量改变了有时候系统会自动更新ui导致报错。
只要改成这样就好了：
new Thread(new Runnable() {
@Override
public void run() {
// TODO Auto-generated method stub
List<String>listTemp = new ArrayList<String>();
for(int i = 0; i < 10; i++){
String str = “s”+i;
listTemp.add(str);
}
Message msg = Message.obtain();
msg.obj = listTemp;
msg.what = Constant.MSG_SUCCESS;
myHandler.sendMessage(msg);
}
}).start();
private Handler myHandler = new Handler(new Callback() {
@Override
public boolean handleMessage(Message msg) {
switch (msg.what) {
case Constant.MSG_SUCCESS:
list.addAll((List<String>)msg.obj);
if (adapter != null) {
adapter.notifyDataSetChanged();
}
break;
default:
break;
}
return false;
}
});
这样我们把添加数据都放在主线程，这就万无一失了