This question already has answers here:
What is a NullPointerException, and how do I fix it?
(12 answers)
Closed 8 years ago.
I want to print a box into the Java console using Unicode characters, but for some reason it gives me this runtime error:
--------------------Configuration: PacManGame - JDK version 1.7.0_25 <Default> - <Default>--------------------
Exception in thread "main" java.lang.NullPointerException
at Scoreboard.genTopLine(Scoreboard.java:35)
at Scoreboard.<init>(Scoreboard.java:17)
at PacManGame.main(PacManGame.java:36)
Process interrupted by user.
code: http://pastebin.com/nuAsH857
Does anyone know what's wrong?
topline is actually NOT null - it's perfectly fine.
The problem is the use of System.console() which returns null (and hence you get NPE on .writer()).
Use System.out.println() instead and it'll work just fine.
An explanation as to why System.console() doesn't work in your IDE can be found here
Related
This question already has answers here:
What is a NullPointerException, and how do I fix it?
(12 answers)
Closed 2 years ago.
When i am opening my Arduino IDE on my Raspberry PI 4, its getting JAVA Error:
Exception in thread "main" java.lang.NullPointerException
at processing.app.I18n._(I18n.java:51)
at processing.app.Preferences.init(Preferences.java:210)
at processing.app.Base.main(Base.java:117)
Not sure why this is happening.
Please help me to solve this problem.
i advise you to use optional to avoid NPE
https://docs.oracle.com/javase/8/docs/api/java/util/Optional.html
optional<Integer> optional
= Optional.ofNullable(9455);
This question already has answers here:
While debugging java app what information is shown for a variable in a stack frame [duplicate]
(3 answers)
Closed 4 years ago.
What does 954 mean? I have checked both thread's id and hashcode(), but they don't equal 954.
Also, when using evaluate, there is also a number after #, I think they have the same meaning but still couldn't find out what's the meaning.
Interesting question. I just always took for granted that it is some id that uniquely identifies the object.
Based on that assumption it could for example be the uniqueId() returned by the Java Debugger Interface for an ObjectReference:
https://docs.oracle.com/javase/7/docs/jdk/api/jpda/jdi/
But that is really just an assumption.
This question already has answers here:
A URL specified in a separate line in Java doesn't issue compile-time errors. Why?
(3 answers)
Java Label usage [duplicate]
(2 answers)
Closed 4 years ago.
When I put some comments on my Java code
I miss to put // in the start of the comment line (its content: url)
I expect compilation error but i surprised the comment line is accepted!
Note: I use Java7
// below single line java comment is accepted without starting by //
https://www.google.com/
Kindly any explanation?
Thanks to #Stultuske comment
Yes - thats is accepted because
https: conidered as a java label then the reaming part
//www.google.com/ conidered as a valid java comment
.
// below single line java comment is accepted without starting by //
https://www.google.com/
for(..,..,..){
}
This question already has answers here:
What is a NullPointerException, and how do I fix it?
(12 answers)
Closed 8 years ago.
Crashlytics is showing a few crashes on the following line:
if(appObj.getStationsList().get(tag)!=null){
getStationsList() returns a LinkedHashMap<String, StationInfo>. How can I avoid getting this error? It's ironic that my very check to avoid this error actually resulted in it.
You will have to check:
if(appObj.getStationsList()==null)
replace
if(appObj.getStationsList().get(tag)!=null){
with
if(appObj.getStationsList() !=null && appObj.getStationsList().get(tag)!=null){
}
This question already has answers here:
Closed 11 years ago.
Possible Duplicate:
Why does null reference print as “null”
This is specified in java API. I wonder if this is for compatibility with previous versions of java, or has some other important reasons.
When converting to a String, having null in the message is often more useful than throwing a NullPointerException as you can at least see the rest of the message. The difference is likely to be a pragmatic decision.