ShortCuts.md

What is the best way to tell if a character is a letter or number in Java without using regexes?

Out of the box:

Character.isAlphabetic('a')
Character.isDigit('a')
Character.isLetter('a')

Custom code:

char c = ''
if  (c>='a'&& c<='z') || (c>='A' && c<'Z') || c>='0' && c<='9'){
return true;
}

============================================

Printing string from char array

Out of the box:

new String(strChars);

Custom code:

String fa="";
for(int i;i<ca.length;i++){
   fa+=ca[i];
}

============================================

Sort and array

Out of the box:

Arrays.sort(arr);

Custom code: Bubble sort On2

for(int j=0;j<a.length;j++){
   for(int i;i<a.length-j-1;i++){
      if(a[i]>a[i+1]){
        int swap = a[i];
        a[i] = a[i+1];
        a[i+1] = swap;
      }
   }
}

============================================

Convert array int[] to Array List

Out of the box: (in datatype is Integer and not int)

Integer[] arr = new Integer[] {2,3,4,5,3,3}
List<Integer> int = Arrays.asList(arr);

Custom Code:

    char[] ca = s.toCharArray();
    List<Character> lst = new ArrayList<>();
    for(char c: ca){
        lst.add(c);
    }  

============================================

Find second occurance of char in string

    for (Character c: s.toCharArray()){
        int first = s.indexOf(c);
        int second = s.indexOf(c, first + 1);
        if(second == -1){
            System.out.println(c);
            return c;
        }
    }

============================================

Count number of occurance of char in string

Custom Code:

 String line = "a.b.c.d";
 int count = line.length() - line.replace(".", "").length();

============================================

Recursion

Custom Code:

static int factorial(int n) {
    return n <= 1 ? 1 : n * factorial(n-1);
}

============================================

Initializing 2 D array

Out of the box:

int[][] TwoDarray  =  {  
        {  1,  0, 12, -1 },
        {  7, -3,  2,  5 },
        { -5, -2,  2, -9 }
};

Custom Code:

 for (int i = 0; i < row.length; i++) {
     for (int i = 0; i < col.length; i++) {
         arr[row][col] = data;
     }
 }

============================================

Find Tail or last element in linked list

Out of the box:

LinkedList.getLast();        

Custom Code:

// Iterate through list until last node's current is null
while (current.next != null) {
    current = current.next;
}

Custom Code:

Out of the box:

Custom Code: