Android/Java - 倒数计时器不工作

Question

我正在制作一个计时器作为我的应用程序的一部分。我遵循了一个教程，并对程序进行了一些修改以更好地满足我的需要。但是，当我运行应用程序时，我会得到 timerTextView 的默认值（在 xml 中定义），或者只是随机数。出了什么问题？

更新：以下是活动的完整代码：

public class Main7Activity extends AppCompatActivity {




private TextView countDownText;
private CountDownTimer countDownTimer;
//private long timeLeftInMilliseconds = 1000*60*60*24*7*1;
public TextView textView3;
public TextView textView4;
public TextView textView5;
public TextView textView6;


public long timeLeftInMilliseconds;

//private int daysToGo;



@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main7);




    textView3 = (TextView) findViewById(R.id.testText);
    textView4 = (TextView) findViewById(R.id.testText2);
    textView5 = (TextView) findViewById(R.id.testText3);
    textView6 = (TextView) findViewById(R.id.testText4);






    //textView3.setText(Integer.toString(Main6Activity.progress2));


    Calendar now = Calendar.getInstance();


    textView3.setText("LMP date : " + Main6Activity.textView.getText());

    int currentDayOfYear = now.get(Calendar.DAY_OF_YEAR);



    //Day of year is the LMP date
    now.set(Calendar.DAY_OF_YEAR, Main6Activity.progress2);
    int lmpDate = now.get(Calendar.DAY_OF_YEAR);


    //Day of year is due date
    now.add(Calendar.DAY_OF_YEAR, 7*40);


    textView4.setText("Due Date: " + now.get(Calendar.DATE) + "-"
            + (now.get(Calendar.MONTH) + 1) + "-" + now.get(Calendar.YEAR));

    int dueDate = now.get(Calendar.DAY_OF_YEAR);

    if (dueDate < 365 && lmpDate > 82){
        dueDate = dueDate + (365);
    }

    if (lmpDate<82 && lmpDate>49){
        dueDate = dueDate + lmpDate;
    }



    if (lmpDate<50) {
        textView5.setText("Congratulations on Delivery");
    }

    else {

        textView5.setText(Integer.toString(dueDate));
    }
    //textView5.setText(now.getTime().toString());
    //int currentDayOfYear  = Calendar.DAY_OF_YEAR;

    int daysToGo = dueDate - currentDayOfYear;
    textView6.setText(Integer.toString(daysToGo));





    timeLeftInMilliseconds = 1000*60*60*24*daysToGo;


    countDownText = (TextView) findViewById(R.id.weeks);
    startTimer();

}



public void startTimer(){
    countDownTimer = new CountDownTimer(timeLeftInMilliseconds, 1000) {
        @Override
        public void onTick(long millisUntilFinished) {
            timeLeftInMilliseconds = millisUntilFinished;
            updateTimer();
        }

        @Override
        public void onFinish() {

        }
    }.start();
}


public void updateTimer(){
    int weeks = (int) timeLeftInMilliseconds / 604800000;
    int days = (int) (timeLeftInMilliseconds % 604800000) / 86400000;
    //int hours = (int) (timeLeftInMilliseconds % 86400000) / 3600000;
    //int minutes = (int) (timeLeftInMilliseconds % 3600000) / 60000;
    int seconds = (int) (timeLeftInMilliseconds % 60000) / 1000;

    String timeLeftText;

    timeLeftText = "";
    if (weeks < 10) timeLeftText += "0";
    timeLeftText += weeks;
    timeLeftText += ":";
    if (days < 10) timeLeftText += "0";
    timeLeftText += days;
    //timeLeftText += ":";
    //if (hours < 10) timeLeftText += "0";
    //timeLeftText += hours;
    //timeLeftText += ":";
    //timeLeftText += minutes;
    //timeLeftText += ":";
    if (seconds < 10) timeLeftText += "0";
    timeLeftText += seconds;

    countDownText.setText(timeLeftText);
}



public void editInfo(View v){

    Intent intent = new Intent(Main7Activity.this, Main6Activity.class);
    startActivity(intent);

}

}

我还需要计时器在后台运行。这段代码会这样做吗？

谢谢。

Answer 1

尝试声明这些变量：

    Handler countHandler ;
    Runnable countRunnable ;
    private final long INTERVAL = 1000 ; // this the interval period which the timer will be triggered each time

然后像这样改变你的方法：

public void startTimer(){
        countHandler = new Handler() ;
        countRunnable = new Runnable() {
            @Override
            public void run() {
                updateTimer();

                timeLeftInMilliseconds= timeLeftInMilliseconds - INTERVAL ;

                if(timeLeftInMilliseconds>=0){
                    countHandler.postDelayed(this, INTERVAL) ;
                } else {
                    cancelTimer(); // here timer is finished
                }
            }
        } ;
        countHandler.post(countRunnable) ;
    }

    public void cancelTimer(){
        countHandler.removeCallbacks(countRunnable);
    }

Answer 2

试试下面的代码。

Timer_Service.java

import android.app.Service;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Handler;
import android.os.IBinder;
import android.preference.PreferenceManager;
import android.support.annotation.Nullable;
import android.util.Log;

import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.Timer;
import java.util.TimerTask;
import java.util.concurrent.TimeUnit;


public class Timer_Service extends Service {

    public static String str_receiver = "your_package_name.receiver";

    private Handler mHandler = new Handler();
    Calendar calendar;
    SimpleDateFormat simpleDateFormat;
    String strDate;
    Date date_current, date_diff;
    SharedPreferences mpref;
    SharedPreferences.Editor mEditor;

    private Timer mTimer = null;
    public static final long NOTIFY_INTERVAL = 1000;
    Intent intent;

    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }

    @Override
    public void onCreate() {
        super.onCreate();

        mpref = PreferenceManager.getDefaultSharedPreferences(getApplicationContext());
        mEditor = mpref.edit();
        calendar = Calendar.getInstance();
        simpleDateFormat = new SimpleDateFormat("HH:mm:ss");

        mTimer = new Timer();
        mTimer.scheduleAtFixedRate(new TimeDisplayTimerTask(), 5, NOTIFY_INTERVAL);
        intent = new Intent(str_receiver);
    }


    class TimeDisplayTimerTask extends TimerTask {

        @Override
        public void run() {
            mHandler.post(new Runnable() {

                @Override
                public void run() {

                    calendar = Calendar.getInstance();
                    simpleDateFormat = new SimpleDateFormat("HH:mm:ss");
                    strDate = simpleDateFormat.format(calendar.getTime());
                    Log.e("strDate", strDate);
                    twoDatesBetweenTime();
                }
            });
        }
    }

    public String twoDatesBetweenTime() {

        try {
            date_current = simpleDateFormat.parse(strDate);
        } catch (Exception e) {

        }

        try {
            date_diff = simpleDateFormat.parse(mpref.getString("data", ""));
        } catch (Exception e) {

        }

        try {
            long diff = date_current.getTime() - date_diff.getTime();
            int int_hours = Integer.valueOf(mpref.getString("hours", ""));

            long int_timer = TimeUnit.HOURS.toMillis(int_hours);
            long long_hours = int_timer - diff;
            long diffSeconds2 = long_hours / 1000 % 60;
            long diffMinutes2 = long_hours / (60 * 1000) % 60;
            long diffHours2 = long_hours / (60 * 60 * 1000) % 24;


            if (long_hours > 0) {
                String str_testing = diffHours2 + ":" + diffMinutes2 + ":" + diffSeconds2;

                Log.e("TIME", str_testing);

                fn_update(str_testing);
            } else {
                mEditor.putBoolean("finish", true).commit();
                mTimer.cancel();
            }
        } catch (Exception e) {
            mTimer.cancel();
            mTimer.purge();
        }

        return "";
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        Log.e("Service finish", "Finish");
    }

    private void fn_update(String str_time) {

        intent.putExtra("time", str_time);
        sendBroadcast(intent);
    }
}

您的 Timer.java 活动：

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.preference.PreferenceManager;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

import java.text.SimpleDateFormat;
import java.util.Calendar;


public class Timer extends AppCompatActivity implements View.OnClickListener {

    private Button btn_start, btn_cancel;
    private TextView tv_timer;
    String date_time;
    Calendar calendar;
    SimpleDateFormat simpleDateFormat;
    EditText et_hours;

    SharedPreferences mpref;
    SharedPreferences.Editor mEditor;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_timer);
        init();
    }

    private void init() {
        btn_start = (Button) findViewById(R.id.btn_timer);
        tv_timer = (TextView) findViewById(R.id.tv_timer);
        et_hours = (EditText) findViewById(R.id.et_hours);
        btn_cancel = (Button) findViewById(R.id.btn_cancel);

        btn_start.setOnClickListener(this);
        btn_cancel.setOnClickListener(this);

        mpref = PreferenceManager.getDefaultSharedPreferences(getApplicationContext());
        mEditor = mpref.edit();

        try {
            String str_value = mpref.getString("data", "");
            if (str_value.matches("")) {
                et_hours.setEnabled(true);
                btn_start.setEnabled(true);
                tv_timer.setText("");

            } else {

                if (mpref.getBoolean("finish", false)) {
                    et_hours.setEnabled(true);
                    btn_start.setEnabled(true);
                    tv_timer.setText("");
                } else {

                    et_hours.setEnabled(false);
                    btn_start.setEnabled(false);
                    tv_timer.setText(str_value);
                }
            }
        } catch (Exception e) {

        }
    }

    @Override
    public void onClick(View v) {

        switch (v.getId()) {
            case R.id.btn_timer:


                if (et_hours.getText().toString().length() > 0) {

                    int int_hours = Integer.valueOf(et_hours.getText().toString());

                    if (int_hours <= 24) {


                        et_hours.setEnabled(false);
                        btn_start.setEnabled(false);


                        calendar = Calendar.getInstance();
                        simpleDateFormat = new SimpleDateFormat("HH:mm:ss");
                        date_time = simpleDateFormat.format(calendar.getTime());

                        mEditor.putString("data", date_time).commit();
                        mEditor.putString("hours", et_hours.getText().toString()).commit();


                        Intent intent_service = new Intent(getApplicationContext(), Timer_Service.class);
                        startService(intent_service);
                    } else {
                        Toast.makeText(getApplicationContext(), "Please select the value below 24 hours", Toast.LENGTH_SHORT).show();
                    }
/*
                    mTimer = new Timer();
                    mTimer.scheduleAtFixedRate(new TimeDisplayTimerTask(), 5, NOTIFY_INTERVAL);*/
                } else {
                    Toast.makeText(getApplicationContext(), "Please select value", Toast.LENGTH_SHORT).show();
                }
                break;


            case R.id.btn_cancel:


                Intent intent = new Intent(getApplicationContext(), Timer_Service.class);
                stopService(intent);

                mEditor.clear().commit();

                et_hours.setEnabled(true);
                btn_start.setEnabled(true);
                tv_timer.setText("");

                break;
        }
    }

    private BroadcastReceiver broadcastReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            String str_time = intent.getStringExtra("time");
            tv_timer.setText(str_time);
        }
    };

    @Override
    protected void onResume() {
        super.onResume();
        registerReceiver(broadcastReceiver, new IntentFilter(Timer_Service.str_receiver));

    }

    @Override
    protected void onPause() {
        super.onPause();
        unregisterReceiver(broadcastReceiver);
    }
}

您的 activity_timer.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <EditText
        android:id="@+id/et_hours"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginRight="5dp"
        android:hint="Hours"
        android:inputType="time" />


    <Button
        android:id="@+id/btn_timer"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_above="@+id/btn_cancel"
        android:text="Start Timer" />

    <Button
        android:id="@+id/btn_cancel"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:text="cancel timer" />


    <TextView
        android:id="@+id/tv_timer"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:text="00:00:00"
        android:textColor="#000000"
        android:textSize="25dp" />

</RelativeLayout>

资源参考：this link。

您需要根据您的要求进行一些修改。即使您关闭应用程序，倒计时仍会继续。