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Questions tagged [java.lang.class]

Java.lang.class is a runtime representation of classes and interfaces.

97 questions
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java.lang.RuntimeException: Unable to start activity ComponentInfo: java.lang.NullPointerException: storage == null

*I am trying to add items to the list view dynamically. But, I am getting a run time exception.Please help. Is there a problem with the global variable "values"? I tried to debug by printing the logs and I am able to see the values stored in the…
Conans
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11
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3 answers

Does Class.newInstance() follow the "Abstract factory" design pattern?

I have started reading Joshua Bloch's "Effective Java" (second edition). While reading item 2 (Consider a builder when faced with many constructor parameters), there is a particular statement that the author makes w.r.t the Class.newInstance()…
divesh premdeep
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9
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2 answers

Java: Subclassing a genericised class

I have a genericised class that I wish to subclass as follows: public class SomeTable extends BaseTable { public SomeTable(int rows, int cols) { super(rows, cols, SomeTableEntry.class); …
bguiz
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9
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2 answers

NetBeans IDE 7.2.1 cannot access java.lang Fatal Error: Unable to find package java.lang in classpath or bootclasspath

I need help with android project inside NetBeans. I Just opened project which is created in NetBeans and I have some issues with "cannot access java.lang Fatal Error: Unable to find package java.lang in classpath or bootclasspath" This is sample…
Nezir
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8
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4 answers

What is the role of static keyword in importing java.lang.System class?

I don't understand the meaning of the keyword static when I import System class: import static java.lang.System.* I'm reading the book about Java and it's written there: Any import declaration that doesn't use the word static must start with…
Green
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6
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3 answers

(java.lang.String) cannot be applied to (java.lang.Object)

Ive a Listner class called TopicS Im trying to call it from a gui called readMessages When Im trying to run the class TopicS using the following method, private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) { …
skal
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5
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3 answers

java.lang.ClassNotFoundException: org.json.JSONException

I am building a simple maven project. I used build path to add json as a third party library and also added it to web-inf library. In the end, i added the dependency in pom.xml. However, with all the effort above, i still get this exception. Any…
zwlgator
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5
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3 answers

Is there a list of thread-safe classes in Java?

I am trying to apply the lessons from reading Java Concurrency In Practice with regards to declaring whether classes that I write are either thread-safe or that they contain unsynchronised mutable state. I think this is a good idea because it…
Matt
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5
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1 answer

Trouble in eclipse: java.lang.ClassCastException

it's been two days that I constantly get an error dialog box every 45 seconds with the title of : Multiple problems have occurred and under it says: java.lang.ClassCastException and in the details there is a repeated line which…
Reza_Rg
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4
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1 answer

.class == getClass() test fails

Here's a small code I wrote to check the (is it called reflection API? not sure) classes at runtime, however I am not getting the intended results. Here is the code: public class Outer { public Outer(){ System.out.println("Outer…
Anurupa_Dey
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4
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4 answers

Java: .class file and java.lang.Class

Is java.lang.Class the same as the actual .class file? i.e. is the content equivalent? I want to send the .class over socket, and was wondering if instead of trying to find and load the actual .class file, if I could just transmit the…
sivabudh
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3
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3 answers

Jenkins -- build a job with cli results in java.lang.NullPointerException

all I apologize if this has been asked before but I cannot find a suitable post anywhere. I am trying to build a job in my Jenkins instance using the Jenkins cli with jankins-cli.jar. I am able to display the help information using: java -jar…
cpow
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3
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1 answer

Java: Why does "Character newChar = 'c' " work if Character is a wrapper class? How come it doesn't need a constructor?

These are both fine for me: Example 1: Character newCharacter = 'c'; Example 2: Character newCharacterOther = new Character('c'); But what are the differences? In the first example, how does the Character class know to set its value to "c" without…
Alexandros Kourtis
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3
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2 answers

Is classOf[] in Scala 2.8 different from 2.7?

I have an interface from Java public class IJava { ... public java.lang.Class getType(); ... } It is inherited in Scala class CScala { def getType() = classOf[Foo] } It worked in Scala 2.7.7. But in 2.8.0.RC1, I get type mismatch; …
redtank
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2
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2 answers

Class required a bean of type 'java.lang.String' that could not be found

I try to a mailservice in Spring. I use Spring-Boot version 2.1.7.Release and amazon-sqs-java-messaging-lib version 1.0.8. My code looks like: @Service @RequiredArgsConstructor public class MailService { private static final Logger logger =…
Arthurofos
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