for(int i=0;i<n;i++){
for(int j=0;j<26;j++){
if(str.charAt(i)== strChar.charAt(j) )
* strSet1.append(str.charAt(i));
}
* strSet2.append(str.charAt(i));
}
Exception:
Exception in thread "main" java.lang.NullPointerException
at AterSeries.main(AterSeries.java:33)
why this code gives null pointer exception
warning: Null pointer access: The variable strSet1 can only be null at this location Null pointer access: The variable strSet2 can only be null at this location
Are
strSet1
andstrSet2
initialized before this? If they are null, you'd get aNullPointerException
.* EDIT *
You cannot call
.append()
(or any other method) on a variable that isnull
. Initialize them as: