我现在每次都会收到这个错误
inside public void onResponse(呼叫,响应响应){：
inside public void onResponse(呼叫,响应响应){：
mContext.runOnUiThread(new Runnable() {
@Override
public void run() {
LocalDBUtility local=LocalDBUtility.getInstance();
//code
}
在我的单例类LocalDBUtility中
static LocalDBUtility localDBUtility;
private LocalDBUtility(){
}
public static LocalDBUtility getInstance(){
if(localDBUtility==null){
synchronized (localDBUtility) {
localDBUtility = new LocalDBUtility();
}
return localDBUtility;
}else {
return localDBUtility;
}
}
我想知道是什么导致了NPE？
堆栈跟踪：
java.lang.NullPointerException: Null pointer exception during instruction 'monitor-enter v1'
at com.utilities.LocalDBUtility.getInstance(LocalDBUtility.java:34)
at com.MainActivity$4.run(MainActivity.java:386)
at android.app.Activity.runOnUiThread(Activity.java:5506)
at
retrofit2.ExecutorCallAdapterFactory$ExecutorCallbackCall$1$1.run(ExecutorCallAdapterFactory.java:68)
at android.os.Handler.handleCallback(Handler.java:815)
at android.os.Handler.dispatchMessage(Handler.java:104)
at android.os.Looper.loop(Looper.java:194)
at android.app.ActivityThread.main(ActivityThread.java:5763)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:960)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755
解决方法
if(localDBUtility==null){
synchronized (localDBUtility) {
如果localDBUtility为null,则无法对其进行同步调用.您只能在实例化对象上进行同步.
