我目前正在开发我的第一个完整的 Android 应用程序。我正在开发一个数学大脑训练游戏，所以我需要一个倒计时器。因此，我使用 Android 的 CountDownTimer 来构建它。
以下是我的 GameActivity.java 类的 Java 代码，我用它来控制我的游戏。
package lk.iit.mobiletechnology.mathematicsbraintrainer;
import java.util.concurrent.TimeUnit;
import lk.iit.mobiletechnology.mathematicsbraintrainer.entity.Challenge;
import lk.iit.mobiletechnology.mathematicsbraintrainer.entity.Game;
import android.annotation.SuppressLint;
import android.annotation.TargetApi;
import android.graphics.drawable.Drawable;
import android.os.Build;
import android.os.Bundle;
import android.os.CountDownTimer;
import android.support.v7.app.ActionBarActivity;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.TextView;
@TargetApi(Build.VERSION_CODES.LOLLIPOP)
@SuppressLint("NewApi")
public class GameActivity extends ActionBarActivity {
private Game game;
private Challenge currentChallenge;
private int questionCount;
private TextView timeView;
private TextView question;
private EditText inputField;
private static final String TAG = "Brain Trainer" ;
private static final int MAXIMUM_QUESTIONS = 10;
public static final String KEY_DIFFICULTY = "lk.iit.mobiletechnology.mathematicsbraintrainer.difficulty";
public static final int DIFFICULTY_NOVICE = 0;
public static final int DIFFICULTY_EASY = 1;
public static final int DIFFICULTY_MEDIUM = 2;
public static final int DIFFICULTY_GURU = 3;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_game);
int difficultyLevel = this.getIntent().getIntExtra(KEY_DIFFICULTY, GameActivity.DIFFICULTY_NOVICE);
this.game = new Game(GameActivity.MAXIMUM_QUESTIONS, difficultyLevel);
this.questionCount = 0;
this.question = (TextView)(this.findViewById(R.id.question_text));
currentChallenge = this.game.getChallenges().get(questionCount);
question.setText(currentChallenge.toString());
this.timeView = (TextView)(this.findViewById(R.id.time_text));
timeView.setText("00:10");
final CountDownMachine timer = new CountDownMachine(10000, 1000);
timer.start();
this.setButtonClickListener();
}
private void setButtonClickListener() {
Button testButton = (Button)(findViewById(R.id.test_button));
inputField = (EditText)(findViewById(R.id.question_input));
testButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
double inputValue = Double.parseDouble(inputField.getText().toString());
ImageView imageView = (ImageView)(findViewById(R.id.answer_feedback));
Drawable drawable;
if(questionCount < 10) {
if(currentChallenge.correctAnswer(inputValue)) {
drawable = getResources().getDrawable(R.drawable.fixed_correct_image);
imageView.setImageDrawable(drawable);
}
else {
drawable = getResources().getDrawable(R.drawable.fixed_wrong_image);
imageView.setImageDrawable(drawable);
}
questionCount++;
if(questionCount == 5) {
//Intent intent = new Intent(, UserEntryActivity.class);
finish();
}
currentChallenge = game.getChallenges().get(questionCount);
question.setText(currentChallenge.toString());
inputField.setText(" ?");
}
}
});
}
@TargetApi(Build.VERSION_CODES.LOLLIPOP)
@SuppressLint("NewApi")
public class CountDownMachine extends CountDownTimer {
public CountDownMachine(long millisInFuture, long countDownInterval) {
super(millisInFuture, countDownInterval);
}
@TargetApi(Build.VERSION_CODES.LOLLIPOP)
@SuppressLint("NewApi")
@Override
public void onTick(long millisUntilFinished) {
long timeRemaining = millisUntilFinished;
String text = String.format("%02d:%02d", (TimeUnit.MILLISECONDS.toMinutes(timeRemaining) - TimeUnit.HOURS.toMinutes(TimeUnit.MILLISECONDS.toHours(timeRemaining))), (TimeUnit.MILLISECONDS.toSeconds(timeRemaining) - (TimeUnit.MINUTES.toSeconds(TimeUnit.MILLISECONDS.toMinutes(timeRemaining)))));
timeView.setText(text);
}
@Override
public void onFinish() {
ImageView imageView = (ImageView)(findViewById(R.id.answer_feedback));
Drawable drawable;
if(!(inputField.getText().toString().equals(""))) {
double inputValue = Double.parseDouble(inputField.getText().toString());
if(questionCount < 10) {
if(currentChallenge.correctAnswer(inputValue)) {
drawable = getResources().getDrawable(R.drawable.fixed_correct_image);
imageView.setImageDrawable(drawable);
}
else {
drawable = getResources().getDrawable(R.drawable.fixed_wrong_image);
imageView.setImageDrawable(drawable);
}
}
}
else {
drawable = getResources().getDrawable(R.drawable.fixed_wrong_image);
imageView.setImageDrawable(drawable);
}
questionCount++;
if(questionCount == 5) {
finish();
}
currentChallenge = game.getChallenges().get(questionCount);
question.setText(currentChallenge.toString());
inputField.setText(" ?");
timeView.setText("00:10");
}
}
}
定义布局的关联activity_game.xml如下:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:background="@color/background"
tools:context="lk.iit.mobiletechnology.mathematicsbraintrainer.GameActivity" >
<TextView
android:id="@+id/time_text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:textSize="15sp"
android:textStyle="bold"
android:textColor="#000"
/>
<TextView
android:id="@+id/question_text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:textSize="15sp"
android:textStyle="bold"
android:textColor="#000"
android:layout_below="@+id/time_text"
/>
<EditText
android:id="@+id/question_input"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:inputType="numberDecimal|numberSigned"
android:text=" ?"
android:layout_below="@+id/question_text"
android:background="#fff"
/>
<ImageView
android:id="@+id/answer_feedback"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:paddingTop="@dimen/image_text_gap"
android:layout_below="@+id/question_input"
android:layout_centerHorizontal="true"
/>
<Button
android:id="@+id/test_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Test"
android:layout_below="@+id/answer_feedback"
android:layout_centerHorizontal="true"
/>
</RelativeLayout>
请注意，这个 java 类仍然没有涵盖全部要求，但它能够在每次游戏期间触发 10 个问题。 我已经引入了计时器，但自从调用timer.start()方法以来，我不断收到以下异常:
Android IllegalAccessError java.util.concurrent.TimeUnit.toMinutes
由于我是这个开发领域的新手，而且很难找到合适的解决方案，如果有人可以帮助我解释为什么我会得到这个以及存在什么样的解决方案，我将不胜感激。
这是我收到的异常的 logcat 内容:
03-06 01:52:59.328: D/AndroidRuntime(278): Shutting down VM
03-06 01:52:59.328: W/dalvikvm(278): threadid=1: thread exiting with uncaught exception (group=0x4001d800)
03-06 01:52:59.348: E/AndroidRuntime(278): FATAL EXCEPTION: main
03-06 01:52:59.348: E/AndroidRuntime(278): java.lang.IllegalAccessError: tried to access method java.util.concurrent.TimeUnit.toMinutes:(J)V from class lk.iit.mobiletechnology.mathematicsbraintrainer.GameActivity$CountDownMachine
03-06 01:52:59.348: E/AndroidRuntime(278): at lk.iit.mobiletechnology.mathematicsbraintrainer.GameActivity$CountDownMachine.onTick(GameActivity.java:108)
03-06 01:52:59.348: E/AndroidRuntime(278): at android.os.CountDownTimer$1.handleMessage(CountDownTimer.java:124)
03-06 01:52:59.348: E/AndroidRuntime(278): at android.os.Handler.dispatchMessage(Handler.java:99)
03-06 01:52:59.348: E/AndroidRuntime(278): at android.os.Looper.loop(Looper.java:123)
03-06 01:52:59.348: E/AndroidRuntime(278): at android.app.ActivityThread.main(ActivityThread.java:4627)
03-06 01:52:59.348: E/AndroidRuntime(278): at java.lang.reflect.Method.invokeNative(Native Method)
03-06 01:52:59.348: E/AndroidRuntime(278): at java.lang.reflect.Method.invoke(Method.java:521)
03-06 01:52:59.348: E/AndroidRuntime(278): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
03-06 01:52:59.348: E/AndroidRuntime(278): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
03-06 01:52:59.348: E/AndroidRuntime(278): at dalvik.system.NativeStart.main(Native Method)
最佳答案
不要使用TimeUnit将毫秒转换为秒、分钟等，自己动手即可。
int seconds = (millis / 1000) % 60;
int minutes = millis / (1000 * 60);
显然，当 TimeUnit 在运行时不可用时，您会收到此错误，请参阅此处:
Android IllegalAccessError java.util.concurrent.TimeUnit.toHours
关于java - Android IllegalAccessError java.util.concurrent.TimeUnit.toMinutes，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/28886607/