java lang nullpointerexception fix

The exception of the null pointer is disgusting, I am afraid is the actual application of the most frequently occurring anomalies, the following is how to avoid nullpointerexception appearance of the technique Before using an object, it is best to know if they are possible null, and if not, use the IF statement to determine whether to use an object, or to traverse a collection, you need to make sure that they are non-empty. It's a rule that w

nullpointerexception is considered the most common mistake of Java programmers. Lang ensures that you do not make the same mistake. Nullpointerexception is not thrown even if a null value is passed to indexof () or other such methods. Indexof () will return-1 directly.In this way, only a few lines of simple code can b

Package java. Lang; Import java. Io .*;Import java. util. properties;Import java. util. propertypermission;Import java. util. stringtokenizer;Import java. Security. accesscontroller;Imp

. Examples and instructions3.1 search for all methods declared in the classImport java. Lang. Reflect .*; Public class Method1 { Private int F1 ( Object P, int X) throws nullpointerexception { If (P = NULL) Throw new nullpointerexception (); Return X; } Public static void main (string ARGs []) { Try { Class CLS = Clas

. facesservlet is not found, but I put the class package in classpath, which can be seen in "Libraries" of Eclipse. Why? Why does Tomcat go to WEB-INF/classes to find this file? It took me a whole day to solve this problem. Refer to the two articles1. http://dev.eclipse.org/mhonarc/lists/wtp-jsf-dev/msg00158.html2. http://forum.java.sun.com/thread.jspa? Forumid = 427 threadid = 598929 Step 1:Deploy the jar package in class_path to the WEB-INF directory. This is configured in the properties of t

Exception one,Java. Lang. illegalargumentexception: view not attached to Window ManagerAt Android. View. windowmanagerimpl. findviewlocked (windowmanagerimpl. Java: 664)At Android. View. windowmanagerimpl. removeview (windowmanagerimpl. Java: 354)At Android. View. windowmanagerimpl $ compatmodewrapper. removeview (wind

. classnotfoundexception ".Immediately exiting rose results in a "Java. Lang. nullpointerexception" WarningAnd the Rose does not respond. Cause: This is usually due to a broken Microsoft Java Vm, but may be due to a missingRegistry entry. Resolution: First, confirm that the Windows registry value "trustedclassp

Package java. Lang. Reflect; Import java. Lang. Ref .*;Import java. util .*; Import sun. Misc. proxygenerator; /*** Example of using proxy*Interface TT {String getst ();} Class STT implements TT {Public String getst (){Return "lqtest ";}} Class myhandler implements invocatio

12-19 12:12:42. 701: E/androidruntime (626): Java. lang. runtimeexception: unable to start activity componentinfo {COM. CLM. activity/COM. CLM. activity. registactivity}: Java. lang. nullpointerexception 12-19 12:12:42. 701: E/androidruntime (626 ):At com. CLM. activity.

Package java. Lang;Import java. Io .*; /**** Throwable is the parent class of all errors and exceptiong.* Note that there are four constructors:* Throwable ()* Throwable (string message)* Throwable (throwable cause)* Throwable (string message, throwable cause)** Comment by liqiang**/Public class throwable implements serializable {Private Static final long serialv