Will be solving some Coding challenges in Java (based on codewars-kata's).

Might also create a handy cheat-sheet of frequenly used Java methods.

1. Convert String to Char array:

   char[] ch = StringArray.toCharArray();
   

2. Convert a characet to Uppercase:

   Character.toUpperCase(ch);
   

3. You can also append an empty string using += same as Python, but avoid it and try using Sringbuilder:

   StringBuilder bld = new StringBuilder();
   for (int i = 0; i < arrayOfStrings.length; ++i) {
   	bld.append(arrayOfStrings[i]);
   }
   return bld.toString();
   

4. Sort an array:

   Arrays.sort(args);
   

5. Convert string to lower-case:

   string_value.toLowerCase();
   

6. Dictionaries in Java are hash-maps:

   HashMap<Character, Integer> hm = new HashMap<>();
   

7. For-looping through HashMaps to get key/values:

   import java.util.HashMap;
   import java.util.Map;
   for(final Map.Entry entry: counter.entrySet()){
   	// or whatever you want to do		
   	if((int)entry.getValue() >= 2) duplicates += 1;
   }
   

8. Use an int value for String:

   int num = 5;
   String.valueOf(num);
   

9. Get range/length of an int:

   int length = String.valueOf(num).length();
   

10. Convert character to its desired int using ASCII: (The difference between character and desired integer is always 48, 48 in ASCII represents character:'0')

    char digit = '6'
    digit - '0' == 6;