How would this be coded in java not using loops?

The goal is below:

public boolean validateChar(char ch)

This method takes a character, and validates that it is one of the allowed characters in the input string. It returns true if it is, and false otherwise.

With constraints:

Your code must handle quite a bit of error checking. The strings being passed in must:

• include only the characters '4', '2' and '_',
• have exactly a length of three.

If any input string is not formatted according to this, you must return the string, unmodified.

Example Assertions:

assert validateChar('2') : "2 should be a valid char"; assert validateChar('4') : "4 should be a valid char"; assert validateChar('_') : "_ should be a valid char"; assert !validateChar(' ') : "space should not be a valid char"; assert !validateChar('3') : "3 should not be a valid char";