when call calculatestringvalue method on string within main method, works fine. when try call method within printstringswithvalues method, null pointer exception. have string being in arraylist?
public static void main(string[] args){ list<string> testlist = new arraylist<>(); testlist.add("apple"); testlist.add("hello"); printstringswithvalues(testlist);} public static void printstringswithvalues(list<string> strings) { (string string : strings) { system.out.println(string + ", " + calculatestringvalue(string)); } } public static int calculatestringvalue(string word) { int value = 0; for(int j=0; j < word.length(); j++) { if(lettervaluemap.containskey(word.charat(j))) { value += lettervaluemap.get(word.charat(j)); } else{ return -1; } } return value; }
using contextual inference of type of lettervaluemap assume map<character, integer>, tried create such kind of map , assign arbitrary values in order test code.
here did
first declare lettervaluemap variable , feed values using static initialization block
public class nullpointerhandler { private static map<character, integer> lettervaluemap; static { lettervaluemap = new hashmap<character, integer>(); (int = 'a'; i<= 'a'+25; i++) { lettervaluemap.put((char)i, i); } (int = 'a'; i<= 'a'+25; i++) { lettervaluemap.put((char)i, i); } lettervaluemap.put(' ', 32); } then use other part of code unchanged (except have added few more words testing purpose)!
public static void main(string[] args){ list<string> testlist = new arraylist<string>(); testlist.add("apple"); testlist.add("hello"); testlist.add("rome"); testlist.add("rome"); testlist.add("julius cesar"); printstringswithvalues(testlist); } public static void printstringswithvalues(list<string> strings) { (string string : strings) { system.out.println(string + ", " + calculatestringvalue(string)); } } public static int calculatestringvalue(string word) { int value = 0; for(int j=0; j < word.length(); j++) { if(lettervaluemap.containskey(word.charat(j))) { value += lettervaluemap.get(word.charat(j)); } else{ return -1; } } return value; } } testing gives me expected results, without generating null pointer exception
