我一直在学习如何编程和制作应用程序至今已有三个月了，而且我一直在尝试修复此错误的几天，我无法找到，代码的哪一部分有nullpoint :( 我非常感谢你的帮助，谢谢
错误日志：
11-16 23:27:27.618: E/AndroidRuntime(4298): FATAL EXCEPTION: main
11-16 23:27:27.618: E/AndroidRuntime(4298): Process: edu.uco.clam.onyourbike_chapter7, PID: 4298
11-16 23:27:27.618: E/AndroidRuntime(4298): java.lang.RuntimeException: Unable to start activity ComponentInfo{edu.uco.clam.onyourbike_chapter7/edu.uco.clam.onyourbike_chapter7.activities.TimerActivity}: java.lang.NullPointerException
11-16 23:27:27.618: E/AndroidRuntime(4298): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2184)
11-16 23:27:27.618: E/AndroidRuntime(4298): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2233)
11-16 23:27:27.618: E/AndroidRuntime(4298): at android.app.ActivityThread.access$800(ActivityThread.java:135)
11-16 23:27:27.618: E/AndroidRuntime(4298): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
11-16 23:27:27.618: E/AndroidRuntime(4298): at android.os.Handler.dispatchMessage(Handler.java:102)
11-16 23:27:27.618: E/AndroidRuntime(4298): at android.os.Looper.loop(Looper.java:136)
11-16 23:27:27.618: E/AndroidRuntime(4298): at android.app.ActivityThread.main(ActivityThread.java:5001)
11-16 23:27:27.618: E/AndroidRuntime(4298): at java.lang.reflect.Method.invokeNative(Native Method)
11-16 23:27:27.618: E/AndroidRuntime(4298): at java.lang.reflect.Method.invoke(Method.java:515)
11-16 23:27:27.618: E/AndroidRuntime(4298): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
11-16 23:27:27.618: E/AndroidRuntime(4298): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
11-16 23:27:27.618: E/AndroidRuntime(4298): at dalvik.system.NativeStart.main(Native Method)
11-16 23:27:27.618: E/AndroidRuntime(4298): Caused by: java.lang.NullPointerException
11-16 23:27:27.618: E/AndroidRuntime(4298): at edu.uco.clam.onyourbike_chapter7.activities.BaseActivity.setupActionBar(BaseActivity.java:57)
11-16 23:27:27.618: E/AndroidRuntime(4298): at edu.uco.clam.onyourbike_chapter7.activities.BaseActivity.onCreate(BaseActivity.java:85)
11-16 23:27:27.618: E/AndroidRuntime(4298): at edu.uco.clam.onyourbike_chapter7.activities.TimerActivity.onCreate(TimerActivity.java:65)
11-16 23:27:27.618: E/AndroidRuntime(4298): at android.app.Activity.performCreate(Activity.java:5231)
11-16 23:27:27.618: E/AndroidRuntime(4298): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
11-16 23:27:27.618: E/AndroidRuntime(4298): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2148)
11-16 23:27:27.618: E/AndroidRuntime(4298): ... 11 more
这里是BaseActivity文件：
public class BaseActivity extends Activity {
private static String CLASS_NAME;
private NightMode nightMode;
private Notify notify;
public boolean canGoHome = true;
public BaseActivity() {
CLASS_NAME = getClass().getName();
}
@TargetApi(Build.VERSION_CODES.HONEYCOMB)
private void setupActionBar() {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
ActionBar actionBar = getActionBar();
actionBar.setDisplayHomeAsUpEnabled(canGoHome);
}
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Make sure we do nothing silly!
if (BuildConfig.DEBUG) {
StrictMode.setThreadPolicy(new StrictMode.ThreadPolicy.Builder()
.detectAll().penaltyLog().build());
StrictMode.setVmPolicy(new StrictMode.VmPolicy.Builder()
.detectAll().penaltyLog().penaltyDeath().build());
}
int themeID = getIntent().getIntExtra("Theme", -1);
if (themeID != -1) {
setTheme(themeID);
}
boolean isLightTheme = getIntent()
.getBooleanExtra("isLightTheme", true);
notify = new Notify(this);
nightMode = new NightMode(getWindow(), this, true, isLightTheme);
setupActionBar();
}
@Override
public void onResume() {
super.onResume();
// nightMode.startSensing();
}
@Override
public void onPause() {
super.onPause();
// nightMode.stopSensing();
}
private void gotoRoutes() {
Log.d(CLASS_NAME, "gotoRoutes");
Intent routes = new Intent(this, RoutesActivity.class);
startActivity(routes);
}
/**
* Called when the settings button is clicked on.
*
* @param view
* the button clicked on
*/
public void gotoSettings(View view) {
Log.d(CLASS_NAME, "gotoSettings");
Intent settings = new Intent(this, SettingsActivity.class);
startActivity(settings);
}
private void gotoHome() {
Log.d(CLASS_NAME, "gotoHome");
Intent timer = new Intent(this, TimerActivity.class);
timer.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(timer);
}
public void gotoMap() {
Log.d(CLASS_NAME, "gotoMap");
Intent map = new Intent(this, MapActivity.class);
startActivity(map);
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case android.R.id.home:
gotoHome();
return true;
case R.id.menu_settings:
gotoSettings(null);
return true;
case R.id.menu_routes:
gotoRoutes();
return true;
case R.id.menu_map:
gotoMap();
return true;
default:
return super.onOptionsItemSelected(item);
}
}
public void goBack(View view) {
finish();
}
public void notification(String title, String message) {
notify.notify(title, message);
}
}
这里是TimerActivity文件：
public class TimerActivity extends BaseActivity {
private static String CLASS_NAME;
private static long UPDATE_EVERY = 200;
private TextView counter;
private Button start;
private Button stop;
private Handler handler;
private Vibrator vibrate;
private UpdateTimer updateTimer;
private final TimerState timer;
private long lastSeconds;
public TimerActivity() {
CLASS_NAME = getClass().getName();
timer = new TimerState();
canGoHome = false;
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Log.d(CLASS_NAME, "onCreate");
setContentView(R.layout.activity_timer);
// NOTE findViewById must be called after setContentView or we'll get an
// RTE
counter = (TextView) findViewById(R.id.timer);
start = (Button) findViewById(R.id.start_button);
stop = (Button) findViewById(R.id.stop_button);
// NOTE some phone and tablets may not vibrate
vibrate = (Vibrator) getSystemService(VIBRATOR_SERVICE);
if (vibrate == null) {
Log.w(CLASS_NAME, "No vibration service exists.");
}
timer.reset();
stayAwakeOrNot();
}
// Note must be public or RTE
/**
* Called when the start button is clicked on.
*
* @param view
* the button clicked on
*/
public void clickedStart(View view) {
Log.d(CLASS_NAME, "clickedStart");
timer.start();
enableButtons();
handler = new Handler();
updateTimer = new UpdateTimer(this);
handler.postDelayed(updateTimer, UPDATE_EVERY);
lastSeconds = -1; // for initial notification
}
/**
* Called when the stop button is clicked on.
*
* @param view
* the button click on
*/
public void clickedStop(View view) {
Log.d(CLASS_NAME, "clickedStop");
timer.stop();
enableButtons();
handler.removeCallbacks(updateTimer);
updateTimer = null;
handler = null;
}
@Override
public void onStart() {
super.onStart();
Log.d(CLASS_NAME, "onStart");
if (timer.isRunning()) {
handler = new Handler();
updateTimer = new UpdateTimer(this);
handler.postDelayed(updateTimer, UPDATE_EVERY);
}
}
/**
* Enable/disable the stop and start buttons
*/
protected void enableButtons() {
Log.d(CLASS_NAME, "enableButtons");
start.setEnabled(!timer.isRunning());
stop.setEnabled(timer.isRunning());
}
/**
* Change the counter text view to display the current formatted time
*/
protected void setTimeDisplay() {
Log.d(CLASS_NAME, "setTimeDisplay");
counter.setText(timer.display());
}
@Override
public void onResume() {
super.onResume();
Log.d(CLASS_NAME, "onResume");
enableButtons();
setTimeDisplay();
}
@Override
public void onPause() {
super.onPause();
Log.d(CLASS_NAME, "onPause");
}
@Override
public void onStop() {
super.onStop();
Log.d(CLASS_NAME, "onStop");
Settings settings = ((OnYourBike) getApplication()).getSettings();
if (timer.isRunning()) {
handler.removeCallbacks(updateTimer);
updateTimer = null;
handler = null;
}
if (settings.isCaffeinated(this)) {
PowerManager powerManager = (PowerManager) getSystemService(Context.POWER_SERVICE);
PowerManager.WakeLock wakeLock = powerManager.newWakeLock(
PowerManager.FULL_WAKE_LOCK, CLASS_NAME);
if (wakeLock.isHeld()) {
wakeLock.release();
}
}
}
@Override
public void onDestroy() {
super.onDestroy();
Log.d(CLASS_NAME, "onDestroy");
}
@Override
public void onRestart() {
super.onRestart();
Log.d(CLASS_NAME, "onRestart");
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
Log.d(CLASS_NAME, "onCreateOptionsMenu");
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
/**
* Keep the screen on depending on the stay awake setting
*/
protected void stayAwakeOrNot() {
Log.d(CLASS_NAME, "stayAwakeOrNot");
Settings settings = ((OnYourBike) getApplication()).getSettings();
if (settings.isCaffeinated(this)) {
// Log.i(CLASS_NAME, "Staying awake");
getWindow()
.addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
} else {
// Log.i(CLASS_NAME, "Not staying awake");
getWindow().clearFlags(
WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
}
}
// NOTE could be an anonymous inner class - easier to understand this way
class UpdateTimer implements Runnable {
Activity activity;
public UpdateTimer(Activity activity) {
this.activity = activity;
}
/**
* Updates the counter display and vibrated if needed
*/
public void run() {
// Log.d(CLASS_NAME, display);
Settings settings = ((OnYourBike) getApplication()).getSettings();
setTimeDisplay();
if (timer.isRunning()) {
if (settings.isVibrateOn(activity)) {
vibrateCheck();
}
notifyCheck();
}
stayAwakeOrNot();
if (handler != null) {
handler.postDelayed(this, UPDATE_EVERY);
}
}
protected void vibrateCheck() {
long seconds;
long minutes;
Log.d(CLASS_NAME, "vibrateCheck");
timer.elapsedTime();
seconds = timer.seconds();
minutes = timer.minutes();
// NOTE done this way to avoid Array/ArrayList issues
// NOTE hasVibrator() only on API 11+
// NOTE try/catch to stop force close on emulator
// NOTE very easy to get manifest wrong!
try {
// NOTE seconds != lastSeconds so it only vibrates once/second
if (vibrate != null && seconds == 0 && seconds != lastSeconds) {
long[] once = { 0, 100 };
long[] twice = { 0, 100, 400, 100 };
long[] thrice = { 0, 100, 400, 100, 400, 100 };
// every hour
if (minutes == 0) {
Log.i(CLASS_NAME, "Vibrate 3 times");
vibrate.vibrate(thrice, -1);
}
// every 15 minutes
else if (minutes % 15 == 0) {
Log.i(CLASS_NAME, "Vibrate 2 time");
vibrate.vibrate(twice, -1);
}
// every 5 minutes
else if (minutes % 5 == 0) {
Log.i(CLASS_NAME, "Vibrate once");
vibrate.vibrate(once, -1);
}
}
} catch (Exception e) {
Log.w(CLASS_NAME, "Exception: " + e.getMessage());
}
lastSeconds = seconds;
}
protected void notifyCheck() {
long seconds;
long minutes;
long hours;
Log.d(CLASS_NAME, "notifyCheck");
timer.elapsedTime();
seconds = timer.seconds();
minutes = timer.minutes();
hours = timer.hours();
if (minutes % 15 == 0 && seconds == 0 && seconds != lastSeconds) {
String title = getResources().getString(R.string.time_title);
String message = getResources().getString(
R.string.time_running_message);
if (hours == 0 && minutes == 0) {
message = getResources().getString(
R.string.time_start_message);
}
message = String.format(message, hours, minutes);
notification(title, message);
}
lastSeconds = seconds;
}
}
}
答案 0 :(得分：0)
CLASS_NAME似乎是空的。
将log标记字符串设为final并在声明点初始化它：
private static final String CLASS_NAME = TimerActivity.class.getName();
P.S。为什么要覆盖构造函数？由于TimerState对象是最终的并且不需要任何参数，您可以在声明点创建它，初始工作可以在onCreate方法而不是在构造函数中完成