CODEWITHSUNDEEP
java
prabhakar Reddy G
prabhakar Reddy G

Reputation: 1069

Not able to resolve the "NullPointerException"

Am actually trying to get the hashmap value by using get(Object key) function. But the below code is throwing NullPointerException at line 

 count+=hm.get((int)str.charAt(i));

So please help me to fix it.

BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
     String str = String.valueOf(br.readLine());
     HashMap<Integer,Integer> hm =new HashMap<Integer,Integer>();
     hm.put(0, 6);
     hm.put(1, 2);
     hm.put(2, 5);
     hm.put(3, 5);
     hm.put(4, 4);
     hm.put(5, 5);
     hm.put(6, 6);
     hm.put(7, 3);
     hm.put(8, 7);
     hm.put(9, 6);
long count=0;

//System.out.println(hm.get(9));
     for(int i=0;i<str.length();i++)
     {

         count+=hm.get((int)str.charAt(i));
     }
     System.out.println(count);

Upvotes: 1

Views: 72

Answers (3)

Rudra
Rudra

Reputation: 1688

If you want to get rid of the type casting declare a map as

HashMap<Character,Integer> hm =new HashMap<Character,Integer>();
hm.put('0', 6);
hm.put('1', 2);
hm.put('2', 5);
.....
long count=0;

for(int i=0;i<str.length();i++)
{
     count+=hm.get(str.charAt(i));
}

Upvotes: 1

Javy
Javy

Reputation: 954

Maybe the following code is a better choice

firstly you should check that the expression str.charAt(i) can be as a digit. then the digit should exists in the hashmap

char ch = str.charAt(i);
if (Character.isDigit(ch)) {
    if (hm.containsKey(Integer.parseInt(String.valueOf(ch)))) {
        count+=hm.get(Integer.parseInt(String.valueOf(ch)));
    }
}

hope that helped

Upvotes: 0

Joni
Joni

Reputation: 111259

When you cast the char that the charAt method returns to int you get the Unicode code point for the character. For example (int)'1' will give you 49, but your map does not have an entry for 49.

To solve this you could define the mapping as HashMap<Character, Integer>, or use Character.getNumericValue instead of casting to int.

hm.get(Character.getNumericValue(str.charAt(i)));

Upvotes: 0

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