### 4.1 Count Words
Write a method that returns the number of words in a String
#### 4.1.1 Example
```
1: String s = "I never saw a purple cow"
2:
3: System.out.println(countWords(s));
4: *** Output ***
5: 6
```
### 4.2 Count the letter 'e'
Write a method that counts the instances of the letter 'e' in a string.
#### 4.2.1 Example
```
1: String s = "I never saw a purple cow"
2:
3: System.out.println(countEs(s));
4: *** Output ***
5: 3
```
### 4.3 Count Alphanumerics
Write a method that returns the number of alphanumeric characters (A-Z, a-z and 0-9) in a string.
#### 4.3.1 Example
```
1: String s = "1984 by George Orwell."
2:
3: System.out.println(countChars(s));
4: *** Output ***
5: 18
```
### 4.4 Reverse String
Write a method that returns a string, reversed
#### 4.4.1 Example
```
1: String s = "I never saw a purple cow"
2:
3: System.out.println(reverse(s));
4: *** Output ***
5: woc elprup a was reven I
```
### 4.5 Palindromes
Write a method to test if a string is a Palindrome
#### 4.5.1 Example
```
1: String sentence = "I never saw a purple cow"
2: String palindrome = "rotavator"
3:
4: System.out.println(isPalindrome(sentence));
5: System.out.println(isPalindrome(palindrome));
6: *** Output ***
7: False
8: True
```
### 4.6 More Palindromes
Write an improved palindrome method that will disregard spaces, punctuation and case and thus recognise sentences such as "A man, a plan, a canal, Panama!" as a palindrome.
#### 4.6.1 Example
```
1: String s = "I never saw a purple cow"
2: String p = "Rise to vote, Sir!"
3:
4: System.out.println(isPalindrome(s));
5: System.out.println(isPalindrome(p));
6: *** Output ***
7: False
8: True
```
### 4.7 Remove v*w*ls
Write a method that will replace the vowels in a word with asterisks
#### 4.7.1 Example
```
1: String s = "I never saw a purple cow"
2:
3: star(s)
4: *** Output ***
5: * n*v*r s*w * p*rpl* c*w
```
### 4.8 Spell Out
Write a method to spell out words so that, for example, This becomes T-H-I-S.
#### 4.8.1 Example
```
1: String s = "I never saw a purple cow"
2:
3: spellOut(s)
4: *** Output ***
5: I N-E-V-E-R S-A-W A P-U-R-P-L-E C-O-W
```
### 4.9 Substitution Cipher
In a simple substitution cipher, A =1 , B=2, C=3 etc. Write a method that encodes a sentence using this cipher
#### 4.9.1 Example
```
1: String s = "Hello World"
2:
3: encode(s)
4: *** Output ***
5: 8,5,12,12,15 23,15,18,12,4
```
### 4.10 Decoder
Write a decoder method for your substitution Cipher
#### 4.10.1 Example
```
1: String s = "9 14,5,22,5,18 19,1,23 1 16,21,18,16,12,5 3,15,23"
2:
3: decode(s)
4: *** Output ***
5: i never saw a purple cow
```