java.lang.NullPointerException

[ravian]

String arrays are initialized with null. I tried the following which didn't work for me. What caused this exception?

Code:

String s1[] = new String[5];
System.out.println(s1[0]);
String str = s1[0].toUpperCase();
System.out.println(str);

Output:

Code:

Exception in thread "main" java.lang.NullPointerException

[afsina]

because unlike primitive types, creating an array of Strings does NOT creates actual string objects. it creates only empty holders (references with null values) you will need to assign actual Strings before doing operaitons like toUpperCase();

Make a search with "initializing String Arrays Java" in google. or Read here, a very nice Java resource