这个错误很难找到，因为当我最初启动主要活动并按下帮助按钮（开始Intent启动帮助活动时），没有问题。同样，在帮助活动中按下我做的按钮返回，这启动主要活动的Intent工作正常。
然而，在用户玩游戏并通过屏幕获得游戏并从高分屏幕返回后，有时但不总是按下帮助屏幕将导致应用程序崩溃。这是为什么？我想它与活动生命周期有关，但看到我对Android开发的新手，我一定不能完全理解它。
帮助课程
public class Help extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_help);
final ImageButton back = (ImageButton)findViewById(R.id.back);
back.setOnClickListener(new OnClickListener(){
public void onClick(View view){
finish();
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.help, menu);
return true;
}
}
MainActivity
public class MainActivity extends Activity implements SensorEventListener{
private static final String TAG = "uVuMain";
public SensorManager smanager;
public Boolean playing = false, paused = false, firstPlay = true;
public TextView score;
public MediaPlayer mediaPlayer;
long startTime, elapsedTime, lastUpdate;
float moveIncrement, middle, moveRightLimit, moveLeftLimit,
difficulty;
Timer timer;
Boolean test = true;
ScoreDB scoreDB;
LinkedList<Integer> ll = new LinkedList<Integer>();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
score = (TextView)findViewById(R.id.score);
score.setTextColor(Color.WHITE);
//get the sensor and music ready
smanager = (SensorManager)this.getSystemService(SENSOR_SERVICE);
setVolumeControlStream(AudioManager.STREAM_MUSIC);
mediaPlayer = new MediaPlayer();
mediaPlayer.start();
try {
AssetManager assetManager = getAssets();
AssetFileDescriptor descriptor = assetManager.openFd("uVuLoop.mp3");
mediaPlayer.setDataSource(descriptor.getFileDescriptor(),
descriptor.getStartOffset(), descriptor.getLength());
mediaPlayer.prepare();
mediaPlayer.setLooping(true);
} catch (IOException e) {
Log.d(TAG, "could not load music: "+e.getMessage());
mediaPlayer = null;
}
//mute option
final ImageButton ib = (ImageButton)findViewById(R.id.mute);
ib.setOnClickListener(new OnClickListener(){
public void onClick(View view){
if (mediaPlayer.isPlaying()){
mediaPlayer.pause();
ib.setImageResource(R.drawable.mute);
}
else {
mediaPlayer.start();
ib.setImageResource(R.drawable.unmute);
}
}
});
//pause option
//should not work if game hasn't started or if it's gameover
final ImageButton pause = (ImageButton)findViewById(R.id.pause);
pause.setOnClickListener(new OnClickListener(){
public void onClick(View view){
if (playing & !paused){
playing = false;
paused = true;
pause.setImageResource(R.drawable.play);
//stop the background
//added for testing
RelativeLayout rl = (RelativeLayout) findViewById(R.id.main);
AnimationDrawable frameAnimation = (AnimationDrawable) rl.getBackground();
frameAnimation.stop();
//stop the character animation
ImageView c = (ImageView)findViewById(R.id.mainChar);
c.setImageResource(R.drawable.normal_0);
if (timer != null){
timer.pause();
}
}
else if (!playing & paused) {
playing = true;
paused = false;
pause.setImageResource(R.drawable.pause);
//start the background
//added for testing
RelativeLayout rl = (RelativeLayout) findViewById(R.id.main);
AnimationDrawable frameAnimation = (AnimationDrawable) rl.getBackground();
frameAnimation.start();
if (timer != null){
timer.resume();
}
}
}
});
pause.setEnabled(false);
//access to scoreboard for adding scores
CursorFactory cf = null;
scoreDB = new ScoreDB(this, "scoreDB", cf);
final ImageButton help = (ImageButton)findViewById(R.id.help);
help.setOnClickListener(new OnClickListener(){
public void onClick(View view){
Intent h = new Intent(MainActivity.this, Help.class);
startActivity(h);
}
});
//start the game
final ImageButton start = (ImageButton)findViewById(R.id.start);
start.setOnClickListener(new OnClickListener(){
public void onClick(View view) {
CountDown timer = new CountDown(3000, 500);
timer.start();
pause.setEnabled(true);
start.setEnabled(false);
help.setEnabled(false);
}
});
}
//give the player a moment to get ready
public class CountDown extends CountDownTimer{
public CountDown(long s, long i){
super(s, i);
}
ImageButton countDown = (ImageButton)findViewById(R.id.start);
@Override
public void onFinish() {
countDown.setImageResource(R.drawable.go);
playing = true;
startTime = System.currentTimeMillis();
score.setVisibility(View.VISIBLE);
//Start background animation
RelativeLayout rl = (RelativeLayout) findViewById(R.id.main);
rl.setBackgroundResource(R.drawable.background);
AnimationDrawable frameAnimation = (AnimationDrawable) rl.getBackground();
frameAnimation.start();
//Start Character animation
ImageView mainChar = (ImageView)findViewById(R.id.mainChar);
mainChar.setImageResource(R.drawable.maincharacter);
//Make sure gameover screen is invisible
ImageView gameOver = (ImageView)findViewById(R.id.gameover);
gameOver.setVisibility(View.INVISIBLE);
if (firstPlay){
//Calculate screen movement
int[]posXY= new int[2];
mainChar.getLocationInWindow(posXY);
middle = posXY[0];
//changed from .005 to .01 for faster start
moveIncrement = (float)(middle*.01);
moveRightLimit = (float) (middle+0.5*middle);
moveLeftLimit= (float)(middle-0.5*middle);
firstPlay = false;
}
mainChar.setX(middle);
//Start the clock
timer = new Timer(startTime);
}
@Override
public void onTick(long millisUntilFinished) {
performTick(millisUntilFinished, countDown);
}
}
public void performTick(long millisUntilFinished, ImageButton count){
int remaining = Math.round(millisUntilFinished * 0.001f);
if (remaining == 3){
count.setImageResource(R.drawable.num_3);
}
else if (remaining == 2){
count.setImageResource(R.drawable.num_2);
}
else if (remaining == 1){
count.setImageResource(R.drawable.num_1);
}
}
public void onSensorChanged(SensorEvent event){
if (event.sensor.getType()==Sensor.TYPE_ACCELEROMETER && playing){
getAccelerometer(event);
}
}
public void getAccelerometer(SensorEvent event){
//In intervals of 10 seconds increase the difficulty
elapsedTime = timer.getElapsedTime()/1000;
difficulty = ((elapsedTime/10)+1);
//only need the y axis and want avg for smoother controls
float[]values = event.values;
int orientation = Math.round(values[1]);
orientation = smoothing(orientation);
score.setText("Walked "+elapsedTime+" feet.\nLevel: "+difficulty);
//Move across screen in a timed interval
//Changed from 15 to 25
if (System.currentTimeMillis()-lastUpdate>25){
lastUpdate = System.currentTimeMillis();
move(orientation, difficulty);
}
}
public void move(int oriented, float difficulty){
//Get character's current position
int[]posXY= new int[2];
ImageView mainChar = (ImageView)findViewById(R.id.mainChar);
mainChar.getLocationInWindow(posXY);
int currentPosition = posXY[0];
if (currentPosition > middle){
}
float delta = (float) (moveIncrement*difficulty*2);
if (oriented>=0){
if (oriented == 0){
oriented = 1;
}
delta = delta*((float)oriented/10);
// Check right boundary
if ((currentPosition+delta)>moveRightLimit){
mainChar.setX(moveRightLimit);
mainChar.setImageResource(R.drawable.fall_right);
gameOver();
}
else{
// Log.d(TAG, "Oriented value: "+oriented+"\nDelta value: "+delta);
mainChar.setX(currentPosition+delta);
tilt(mainChar, currentPosition+delta);
}
}
else {
delta = -delta*((float)oriented/10);
// Check left boundary
if ((currentPosition-delta)<moveLeftLimit){
mainChar.setX(moveLeftLimit);
mainChar.setImageResource(R.drawable.fall_left);
gameOver();
}
else {
// Log.d(TAG, "Oriented value: "+oriented+"\nDelta value: "+delta);
mainChar.setX(currentPosition-delta);
tilt(mainChar, currentPosition-delta);
}
}
}
public void tilt(ImageView mainChar, float position){
if (position< (middle-middle*.10)){
mainChar.setImageResource(R.drawable.maincharacterleft);
}
else if(position>(middle+middle*.10)){
mainChar.setImageResource(R.drawable.maincharacterright);
}
else {
mainChar.setImageResource(R.drawable.maincharacter);
}
}
public void gameOver(){
//stop the background
RelativeLayout rl = (RelativeLayout) findViewById(R.id.main);
AnimationDrawable frameAnimation = (AnimationDrawable) rl.getBackground();
frameAnimation.stop();
//fade in the gameover screen
Animation animation = new AlphaAnimation(0, 1);
animation.setInterpolator(new AccelerateInterpolator());
animation.setDuration(1000);
ImageView gameOver = (ImageView)findViewById(R.id.gameover);
gameOver.setVisibility(View.VISIBLE);
gameOver.startAnimation(animation);
//Reset buttons
ImageButton startbtn = (ImageButton)findViewById(R.id.start);
startbtn.setImageResource(R.drawable.play_again);
playing = false;
ImageButton hlp = (ImageButton)findViewById(R.id.help);
hlp.setEnabled(true);
startbtn.setEnabled(true);
//update scoreboard
scoreDB.addScore((int) elapsedTime);
animation.setAnimationListener(new AnimationListener(){
@Override
public void onAnimationEnd(Animation arg0) {
// TODO Auto-generated method stub
Intent i = new Intent(MainActivity.this, ScoreBoard.class);
startActivity(i);
}
@Override
public void onAnimationRepeat(Animation arg0) {
// TODO Auto-generated method stub
}
@Override
public void onAnimationStart(Animation arg0) {
// TODO Auto-generated method stub
}
});
}
//take average of last 4 values to smooth controls
private int smoothing(int value){
ll.add(value);
if (ll.size()>4){
ll.removeFirst();
}
int sum = 0;
for (Integer i: ll){
sum+=i;
}
int avg = Math.round(sum/((float)ll.size()));
return avg;
}
@SuppressWarnings("static-access")
protected void onResume(){
super.onResume();
if (mediaPlayer != null) {
mediaPlayer.start();
}
smanager.registerListener(this,
smanager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER),
smanager.SENSOR_DELAY_NORMAL);
}
protected void onPause() {
super.onPause();
smanager.unregisterListener(this);
if (mediaPlayer != null) {
mediaPlayer.pause();
if (isFinishing()) {
mediaPlayer.stop();
mediaPlayer.release();
}
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
public void onAccuracyChanged(Sensor sensor, int accuracy) {
// TODO Auto-generated method stub
}
}
我对此感到困惑，在Intent上阅读Android文档似乎没什么帮助。在一个可能相关的说明中，如果音乐静音，当我从帮助屏幕返回时，它会变为未静音。如果这与我的问题有关，请告诉我。
logcat的
10-01 14:44:55.149: E/AndroidRuntime(27704): FATAL EXCEPTION: main
10-01 14:44:55.149: E/AndroidRuntime(27704): Process: com.uVu.caffeineRun, PID: 27704
10-01 14:44:55.149: E/AndroidRuntime(27704): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.uVu.caffeineRun/com.uVu.caffeineRun.Help}: android.view.InflateException: Binary XML file line #1: Error inflating class <unknown>
10-01 14:44:55.149: E/AndroidRuntime(27704): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2184)
10-01 14:44:55.149: E/AndroidRuntime(27704): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2233)
10-01 14:44:55.149: E/AndroidRuntime(27704): at android.app.ActivityThread.access$800(ActivityThread.java:135)
10-01 14:44:55.149: E/AndroidRuntime(27704): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
10-01 14:44:55.149: E/AndroidRuntime(27704): at android.os.Handler.dispatchMessage(Handler.java:102)
10-01 14:44:55.149: E/AndroidRuntime(27704): at android.os.Looper.loop(Looper.java:136)
10-01 14:44:55.149: E/AndroidRuntime(27704): at android.app.ActivityThread.main(ActivityThread.java:5001)
10-01 14:44:55.149: E/AndroidRuntime(27704): at java.lang.reflect.Method.invokeNative(Native Method)
10-01 14:44:55.149: E/AndroidRuntime(27704): at java.lang.reflect.Method.invoke(Method.java:515)
10-01 14:44:55.149: E/AndroidRuntime(27704): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
10-01 14:44:55.149: E/AndroidRuntime(27704): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
10-01 14:44:55.149: E/AndroidRuntime(27704): at dalvik.system.NativeStart.main(Native Method)
10-01 14:44:55.149: E/AndroidRuntime(27704): Caused by: android.view.InflateException: Binary XML file line #1: Error inflating class <unknown>
10-01 14:44:55.149: E/AndroidRuntime(27704): at android.view.LayoutInflater.createView(LayoutInflater.java:620)
10-01 14:44:55.149: E/AndroidRuntime(27704): at com.android.internal.policy.impl.PhoneLayoutInflater.onCreateView(PhoneLayoutInflater.java:56)
10-01 14:44:55.149: E/AndroidRuntime(27704): at android.view.LayoutInflater.onCreateView(LayoutInflater.java:669)
10-01 14:44:55.149: E/AndroidRuntime(27704): at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:694)
10-01 14:44:55.149: E/AndroidRuntime(27704): at android.view.LayoutInflater.inflate(LayoutInflater.java:469)
10-01 14:44:55.149: E/AndroidRuntime(27704): at android.view.LayoutInflater.inflate(LayoutInflater.java:397)
10-01 14:44:55.149: E/AndroidRuntime(27704): at android.view.LayoutInflater.inflate(LayoutInflater.java:353)
10-01 14:44:55.149: E/AndroidRuntime(27704): at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:290)
10-01 14:44:55.149: E/AndroidRuntime(27704): at android.app.Activity.setContentView(Activity.java:1929)
10-01 14:44:55.149: E/AndroidRuntime(27704): at com.uVu.caffeineRun.Help.onCreate(Help.java:20)
10-01 14:44:55.149: E/AndroidRuntime(27704): at android.app.Activity.performCreate(Activity.java:5231)
10-01 14:44:55.149: E/AndroidRuntime(27704): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
10-01 14:44:55.149: E/AndroidRuntime(27704): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2148)
10-01 14:44:55.149: E/AndroidRuntime(27704): ... 11 more
10-01 14:44:55.149: E/AndroidRuntime(27704): Caused by: java.lang.reflect.InvocationTargetException
10-01 14:44:55.149: E/AndroidRuntime(27704): at java.lang.reflect.Constructor.constructNative(Native Method)
10-01 14:44:55.149: E/AndroidRuntime(27704): at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
10-01 14:44:55.149: E/AndroidRuntime(27704): at android.view.LayoutInflater.createView(LayoutInflater.java:594)
10-01 14:44:55.149: E/AndroidRuntime(27704): ... 23 more
10-01 14:44:55.149: E/AndroidRuntime(27704): Caused by: java.lang.OutOfMemoryError
10-01 14:44:55.149: E/AndroidRuntime(27704): at android.graphics.BitmapFactory.nativeDecodeAsset(Native Method)
10-01 14:44:55.149: E/AndroidRuntime(27704): at android.graphics.BitmapFactory.decodeStream(BitmapFactory.java:594)
10-01 14:44:55.149: E/AndroidRuntime(27704): at android.graphics.BitmapFactory.decodeResourceStream(BitmapFactory.java:429)
10-01 14:44:55.149: E/AndroidRuntime(27704): at android.graphics.drawable.Drawable.createFromResourceStream(Drawable.java:840)
10-01 14:44:55.149: E/AndroidRuntime(27704): at android.content.res.Resources.loadDrawable(Resources.java:2110)
10-01 14:44:55.149: E/AndroidRuntime(27704): at android.content.res.TypedArray.getDrawable(TypedArray.java:602)
10-01 14:44:55.149: E/AndroidRuntime(27704): at android.view.View.<init>(View.java:3554)
10-01 14:44:55.149: E/AndroidRuntime(27704): at android.view.View.<init>(View.java:3484)
10-01 14:44:55.149: E/AndroidRuntime(27704): at android.view.ViewGroup.<init>(ViewGroup.java:464)
10-01 14:44:55.149: E/AndroidRuntime(27704): at android.widget.RelativeLayout.<init>(RelativeLayout.java:236)
10-01 14:44:55.149: E/AndroidRuntime(27704): ... 26 more