java lang nullpointerexception java

Actually. I made a mistake when calling a function at the DaO layer. I called myself. A java. Lang. stackoverflowerror error occurs in the recently executed project. After a long time, I also asked experts and checked information. Finally, the problem is solved! Special record! Stackoverflowerror is because the current thread's stack is fullWhich is caused by too many function call levels. For example

The external android project is imported to ecplise. The compilation is normal and an error is returned. The logcat is as follows: 12-19 10:55:25. 915: E/AndroidRuntime (2929): fatal exception: main12-19 10:55:25. 915: E/AndroidRuntime (2929): java. lang. noClassDefFoundError: com. guet. siriCN. mainActivity $1 www.2cto. com12-19 10:55:25. 915: E/AndroidRuntime (2929): at com. XXX. mainActivity.

We are integrating perf4j and javasimon Code When I found some problems, that is, I was running good things in my own test code. When I put it in the project code, I always reported the following error :... caused by: Java. lang. illegalargumentexception: superclass has no null constructors but no arguments were given... compared with the code, spring beans with constructor parameters are not found in your

An exception is thrown when you use javamail to send an email: Java. Lang. securityexception: sha1 digest error for COM/Sun/mail/SMTP/smtptransport. Class I am depressed for a long time, and finally found two problems 1. import all jar files in the project (this is not enough. It can be sent at this time, but an exception will always be reported. For the solution, refer to article 2. add all jar files to

The header is finally fixed A backend management system developed based on Struts + hibernate. The functions include complete permission management and information publishing functions.Development Environment: eclipse3.01 + myeclipse3.84 When importing a project to eclipse3.1.1 + myeclipse4.1.x, the system always prompts "the type of Java. Lang. object cannot be parsed. Indirectly referenced it from the r

In a project, the anlr component is required to import the antlr-2.7.2.jar from the Lib of struts 2. After running, the following error is prompted: Java. Lang. nosuchmethoderror: anlr. Collections. Ast. Getline () I So I guess the AST in version 2.7.2 does not use the Getline method. Please try an anlr of a higher version. Import the antlr-2.7.6.jar from the Lib of hibernate 3, and the above error no l

After installing Oracle 10 Gb, run em and the interface is displayed, but an error is reported: Java. Lang. Exception: exception in sending request: NULL Many functions are not available, prompting you to log on again Solution: Find the following file $ ORACLE_HOME \ db_1 \ $ hostname \ sysman \ config \ EMD. Properties The default value of agenttzregion is GMT, which can be changed

Package java. Lang; /*** A subclass of throwable. An application-level exception can be handled in a Catch Block,* It can also be thrown to the top management (encapsulation can be performed as needed when being thrown to the top management)** Comment by liqiang** @ Author Frank Yellin**/Public class exception extends throwable {Static final long serialversionuid =-3387516993124229948l; /**** Constructo

JSP labels have never been used before. Now, after adding JSP labels to the project, a problem occurs: Org. Apache. Jasper. jasperexception: Java. Lang. illegalargumentexception: attribute type = "password" is not allowed This error is introduced in JSP Label Use Type = "password"Class = "formpwdcss" tabindex = "2"/>, The reason is simple: Form: Password conflicts with type = "password". You onl

Oracle 10g installation in Oracle10g + win 7 After logging on to Em, the system prompts java. Lang. Exception: exception in sending request: null. (1) Find the EMD. properties file in sysman under the xxx_orcl file in db_1 under the Oracle installation directory, and change agenttzregion = GMT to agenttzregion = Asia/Chungking. (2) Open the CMD command window and reconfigure em. Set oracle_sid = orc

In Android development, the operations on the thread are miserable. After a thread is started, the thread must stop after the flag is set to false. When we use a thread again, whether the returned value of thread. isalife () is true or false, if we use thread. Start () Again, the following error is returned: Java. Lang. illegalthreadstateexception: thread already started If you want the thread to run a

In Android, you need to use jxl to read and write Excel files. copy the jar package to the project directory, and then use "build path --> Add to build path" to add the package to the project library, the result is that Java is always displayed when the class is instantiated. lang. verifyerror: I cannot explain it. I checked it online and said it was possible that an error occurred while importing the exter

Recently, spring4.x was used to integrate Jackson ------> java. lang. ClassNotFoundException :, Recently, Jackson was integrated with spring4.x, and the results were inexplicably reported. The online retrieval results were all solved by configuring the dependency conditions in the maven or gradle environment; however, the jar package in the eclipseIDE environment should be automatically dependent on the sha

Java. lang. RuntimeException: Invalid action class configuration that references an unknown class named was found online. The most common cause is that the configuration file or field is wrong. The ClassNotFound error is also prompted. Think about the struts2 configuration. The default mode is sington. If you do not configure it in spring. If you want to log on to multiple users at the same time, this excep

Android compatibility problem: java. lang. UnsupportedOperationException solution, androidstudio During Development a few days ago, we encountered such an amazing exception. Some mobile phones could run, but some of them collapsed. Today we sorted out the exception. First, paste the exception information E/AndroidRuntime: FATAL EXCEPTION: mainandroid.view.InflateException: Binary XML file line #13: Error in

public static double rint ( double ):Take the nearest integer (or even if it is the same) and then convert to double typepublic static int round ( float ):Take the nearest integer (if the same is the larger number), and then convert to int typepublic static long round ( double ):Take the nearest integer (if the same is a large number), and then convert to a long typepublic static double ceil ( double ):Returns the smallest integer of the ≥ parameter and then the double typepublic static double f

1. The error "Java. Lang. classnotfoundexception: COM. Microsoft. JDBC. sqlserver. sqlserverdriver" is displayed: The final cause may be as follows: 1. SQL Server 2000 driver for JDBC is not installed 2. Pay attention to you after installationProgramWhether the package of the class has imported three files under the Lib file after the SQL Server 2000 driver for JDBC program is installed: C:/program file

Question: 1. In the Java API Doc, I saw the statement below: This integer need not remain consistent from one execution of an application to another execution of the same application. Does it mean that on each execution, the hashcode may be different?But I run this programme (fragment below) sereral times: System. Out. println ("C1 hashcode:" + c1.hashcode (); system. Out. println ("C2 hashcode:" + c2.hashcode ()); They return the same code

Error message exception in thread "Main" Java. lang. exceptionininitializererrorat Org. hibernate. cfg. configuration. reset (configuration. java: 330) at Org. hibernate. cfg. configuration. My little hibernatedemo example (hibernate3.6.0) has not been changed. I just changed a setting of eclipse Jee 3.6. As shown in the following figure: When you add the user li

An exception occurs after one-to-multiple bidirectional Association of @ onetovers using spring + hibernate Annotations:Java. Lang. nosuchmethoderror: javax. Persistence. oneto133. orphanremoval () ZThis exception usually occurs because the Java ee. Jar version of myeclipse is relatively low, and conflicts with the built-in JPA such as hibernate. Some processing methods on the Internet are to delete the