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extends LinkedList,but use iterator warning that is null  RSS feed

 
Greenhorn
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Where it warns that is null, why is it?


[HENRY: Added Code Tags]
 
Bartender
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I assume it's saying argsStrs is null? That's null because you set it to null. You need to create an array to put the values in.
 
Bartender
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Google App Engine Java Ruby
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Please UseCodeTags and post correct code so that we can point out the exact issue.
 
filson sun
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Mohamed Sanaulla wrote:Please UseCodeTags and post correct code so that we can point out the exact issue.



Thank you !

like that ,I create a project with two classes

one :

import java.util.LinkedList;

public class ArgumentsList extends LinkedList<String> {
public ArgumentsList(){
init();
}

public void init(){
add("-s");
add("-r");
add("-i");
}
}

two:

import java.io.Serializable;
import java.util.Iterator;
import java.util.LinkedList;



public class SD {


public static void main(String args[]){
Iterator<String>argListIterator=new ArgumentsList().iterator();
String argStrs[]=null;
int j=-0;
while (argListIterator.hasNext()) {
argStrs[j] = (String) argListIterator.next();
j++;
}
}


}


-------------------------------------------
But the problem is the same :"Exception in thread "main" java.lang.NullPointerException
at SD.main(SD.java:15)
"
 
Mohamed Sanaulla
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Matthew has mentioned the possible reason for the NullPointerException. You need to create an array object instead of initializing it to null.
 
filson sun
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Mohamed Sanaulla wrote:Matthew has mentioned the possible reason for the NullPointerException. You need to create an array object instead of initializing it to null.


Thank you ! Is there a function to quickly initialize the array? only use for(****){} to initialize it ?
 
Sheriff
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Chrome Eclipse IDE Java Windows
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Please UseCodeTags next time.

Why not use the toArray methods?
This version of the toArray method uses the provided array and stores the elements in that array. If the array is not large enough (like my first example) it will use reflection to create a new array of the exact same type as the given array, in this case a String[].
 
filson sun
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Rob Spoor wrote:Please UseCodeTags next time.

Why not use the toArray methods?
This version of the toArray method uses the provided array and stores the elements in that array. If the array is not large enough (like my first example) it will use reflection to create a new array of the exact same type as the given array, in this case a String[].


Thank you !
 
Rob Spoor
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You're welcome
 
It is sorta covered in the JavaRanch Style Guide.
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