我尝试使用处理程序，但它说'无法解析符号'处理程序''

Question

What do i do to be able to use a handler to update my TextView every 2 secs because right now it comes up with 'cannot resolve symbol"Handler"'

int noStart = 20;
int minus = 5;

public void number(View view) {
    final TextView tx = (TextView) findViewById(R.id.number);

    if(noStart<0){
        new Handler().postDelayed(new Runnable() {
            public void run() {
                noStart -= minus;
                tx.setText(String.valueOf(noStart));
            }
        }, 2000);
    }
}

Answer 1

检查您的活动导入并将此行添加到类中：

import android.os.*

Answer 2

In my case, i refer to a constant of class Handler in outer calss, see as below:

import static *.MyHandler.MSG_WHAT_PING_NETWORK;
public class OuterClass {
    // use MSG_WHAT_PING_NETWORK...
    // ...
}

class MyHandler extends Handler {
    public static final int MSG_WHAT_PING_NETWORK = 99;
    // ...
}

remove the import in outer class can solve the problem.