下面的异常是什么意思;我该怎么解决呢?
这是代码:
Toast toast = Toast.makeText(mContext, "Something", Toast.LENGTH_SHORT);
这是例外:
java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()
at android.os.Handler.<init>(Handler.java:121)
at android.widget.Toast.<init>(Toast.java:68)
at android.widget.Toast.makeText(Toast.java:231)
当前回答
Handler handler2;
HandlerThread handlerThread=new HandlerThread("second_thread");
handlerThread.start();
handler2=new Handler(handlerThread.getLooper());
现在handler2将使用一个不同于主线程的线程来处理消息。
其他回答
我使用下面的代码来显示来自非主线程“context”的消息，
@FunctionalInterface
public interface IShowMessage {
Context getContext();
default void showMessage(String message) {
final Thread mThread = new Thread() {
@Override
public void run() {
try {
Looper.prepare();
Toast.makeText(getContext(), message, Toast.LENGTH_LONG).show();
Looper.loop();
} catch (Exception error) {
error.printStackTrace();
Log.e("IShowMessage", error.getMessage());
}
}
};
mThread.start();
}
}
然后使用如下:
class myClass implements IShowMessage{
showMessage("your message!");
@Override
public Context getContext() {
return getApplicationContext();
}
}
我也有同样的问题，我只是把吐司放在Asynctask<>的onPostExecute()覆盖函数中，它起作用了。
这是因为Toast.makeText()是从工作线程调用的。它应该像这样从主UI线程调用
runOnUiThread(new Runnable() {
public void run() {
Toast toast = Toast.makeText(mContext, "Something", Toast.LENGTH_SHORT);
}
});
Rxjava和RxAndroid用户:
public static void shortToast(String msg) {
Observable.just(msg)
.observeOn(AndroidSchedulers.mainThread())
.subscribe(message -> {
Toast.makeText(App.getInstance(), message, Toast.LENGTH_SHORT).show();
});
}
在执行以下操作之前，我一直得到这个错误。
public void somethingHappened(final Context context)
{
Handler handler = new Handler(Looper.getMainLooper());
handler.post(
new Runnable()
{
@Override
public void run()
{
Toast.makeText(context, "Something happened.", Toast.LENGTH_SHORT).show();
}
}
);
}
并把它变成一个单例类:
public enum Toaster {
INSTANCE;
private final Handler handler = new Handler(Looper.getMainLooper());
public void postMessage(final String message) {
handler.post(
new Runnable() {
@Override
public void run() {
Toast.makeText(ApplicationHolder.INSTANCE.getCustomApplication(), message, Toast.LENGTH_SHORT)
.show();
}
}
);
}
}
