爲Android應用程序工作時間

Question

我正在創建一個非常簡單的應用程序。這是數學類型的遊戲。在產生數學問題的地方，用戶必須在一定的時間內解決數學問題。大量的代碼我已刪除，使其更易於閱讀

import android.app.AlertDialog; 
import android.content.DialogInterface; 
import android.graphics.Color; 
import android.media.MediaPlayer; 
import android.os.Bundle; 
import android.view.View; 
import android.widget.TextView; 
import java.util.Random; 
import android.content.Intent; 
import java.util.concurrent.TimeUnit; 
import android.os.CountDownTimer; 

import com.google.android.gms.ads.*; 
import android.os.Handler; 
import android.os.Looper; 
import android.app.Activity; 

import static android.os.CountDownTimer.*; 

public class activity_2 extends MainActivity implements DialogInterface.OnClickListener{ 

int getWrong=0, num, sum = 0, score = 0, three, four; 

Random rand = new Random(); 
int one = rand.nextInt(10) + 1; 
int two = rand.nextInt(10) + 1; 
int solution = one + two; 
String myString = String.format("%d + %d =", one, two); 

@Override 
public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_2); 

    TextView text = (TextView) findViewById(R.id.Question); 
    text.setText("" + myString); 


    TextView timeSTART = (TextView) findViewById(R.id.TimmerT); 
    timeSTART.setText("10"); 


} 

public void buttonONC_ENTER(View V) { 


    if (solution == sum) { 

     score++; 
     TextView TV = (TextView) findViewById(R.id.SCORE); 
     TV.setText("SCORE: " + score); 

      one = rand.nextInt(10) + 1; 
      two = rand.nextInt(10) + 1; 
      num = rand.nextInt(4) + 1; 
      switch (num) { 
       case 1: 
        solution = one + two; 
        myString = String.format("%d + %d =", one, two); 
        break; 
       case 2: 
        if (one > two) { 
         solution = one - two; 
         myString = String.format("%d - %d =", one, two); 
        } else { 
         solution = two - one; 
         myString = String.format("%d - %d =", two, one); 
        } 
        break; 
       case 3: 
        solution = two + one; 
        myString = String.format("%d + %d =", two, one); 
        break; 
       case 4: 
        if (two > one) { 
         solution = two - one; 
         myString = String.format("%d - %d =", two, one); 
        } else { 
         solution = one - two; 
         myString = String.format("%d - %d =", one, two); 
        } 
        break; 
     } 
    } else { 

     TextView answerT = (TextView)findViewById(R.id.TimmerT); 
     answerT.setText("WRONG"); 
     mistakefinder(); 
    } 


    TextView TV = (TextView) findViewById(R.id.Question); 
    TV.setText("" + myString); 

    sum=0; 
    TextView freshsum = (TextView) findViewById(R.id.ANSWER); 
    freshsum.setText("" + sum); 

    TimmerCLOCK(); 

     } 

    @Override 
    public void onClick(DialogInterface dialog, int which) { 

     switch(which){ 
      case DialogInterface.BUTTON_POSITIVE: 
       Intent intent = new Intent(this, activity_2.class); 
       startActivity(intent); 
       break; 
      case DialogInterface.BUTTON_NEGATIVE: 
       finish(); 
       break; 
     } 
    } 

     public void TimmerCLOCK() { 

     final TextView timmerT = (TextView) findViewById(R.id.TimmerT); 


     countDownTimer = new CountDownTimer(10000, 1000) { 

      public void onTick(long millisUntilFinished) { 
       timmerT.setText("" + String.format(TIMEFORMAT, 
         TimeUnit.MILLISECONDS.toSeconds(millisUntilFinished) - TimeUnit.MINUTES.toSeconds(
           TimeUnit.MILLISECONDS.toMinutes(millisUntilFinished)))); 
       timmerT.setTextColor(Color.WHITE); 
      } 

      public void onFinish() { 
       timmerT.setText("TO SLOW!"); 
       timmerT.setTextColor(Color.RED); 
       mistakefinder(); 

      } 
     }; 

      countDownTimer.start(); 

} 

    public void mistakefinder() { 
     getWrong++; 
     TextView textM = (TextView) findViewById(R.id.MISTAKE); 
     switch (getWrong) { 
      case 1: 
       textM.setCompoundDrawablesWithIntrinsicBounds(R.drawable.x_mark_3_xxl, 0, 0, 0); 
       break; 
      case 2: 

        textM.setCompoundDrawablesWithIntrinsicBounds(R.drawable.two_x, 0, 0, 0); 
        break; 
       case 3: 

        textM.setCompoundDrawablesWithIntrinsicBounds(R.drawable.three_x, 0, 0, 0); 
        break; 
       case 4: 
        AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(activity_2.this); 
        // set title 
        alertDialogBuilder.setTitle("GAMEOVER!"); 
        // set dialog message 
        alertDialogBuilder.setMessage("Your Score: " + score).setCancelable(false); 
        // create alert dialog 

        alertDialogBuilder.setPositiveButton("RETRY", this); 

        alertDialogBuilder.setNegativeButton("EXIT", this); 

        AlertDialog alertDialog = alertDialogBuilder.create(); 
        // show it 
        alertDialog.show(); 
        break; 
      } 
     } 


    } 

我與應用程序時遇到的問題是，當我測試在Android Studio中的應用程序。計時器將工作，如果數學問題解決。定時器不停止計數，並且會有多個定時器同時運行。所以，我的目標是，無論解決方案是對還是錯，當前計時器都需要停止，並且需要開始新計時器。

Answer 1

您可以使用全局參考countDownTimer以取消之前創建一個新的或當問題與解決

if (countDownTimer != null) { 
    countDownTimer.cancel(); 
}