java - 处理程序未实时更新 int

Question

我正在尝试制作一个启动计时器的按钮(仅限秒)。每当按下它时，计时器都会重置回 0，并再次开始每秒递增。这里我有一个处理程序，但它不会实时更新，它仅在您单击按钮时更新。我错过了什么？

public class MainActivity extends Activity {

    Handler mHandler = new Handler();
    int mSeconds;

    @Override
    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        downloadedImg = (ImageView) findViewById(R.id.imageView);
    }

    Runnable UpdateRunnable = new Runnable() {
        @Override
        public void run() {
            updateSec();
        }
    };

    public void updateSec() {
        mSeconds++;
        mHandler.postDelayed(UpdateRunnable, 1000);
    }

    public void clickAsync(View view) {

        new ImageDownloader().execute(downloadUrl);
        Button button = (Button) view;
        mSeconds = 0;

        button.setText("Seconds since clicked: " + mSeconds);
        //actively increment and update seconds on button every second
        //set seconds to 0 on click
        updateSec();
    }
}

Answer 1

it only updates when you click the button. What am I missing?

因为 button.setText 仅在单击 Button 时调用。在递增 mSeconds 之前，在 run() 内调用 button.setText:

    public void run() {
        button.setText("Seconds since clicked: " + mSeconds);
        updateSec();
    }

并在 clickAsync 方法外部访问 button，并在 clickAsync 方法外部声明它。