Tidbits 1

Array

• To return an array, use new[]{i,j}

Character

• valueOf(char)
• charValue()
• isDigit(int)
• isDigit(char)
• isLetter(int)
• isLetter(char)
• isLetterOrDigit(int)
• isLetterOrDigit(char)
• isAlphabetic(int)

String

• isEmpty()
  • jdk6+
  • Is same as s.length()\==0
  • It does not check whitespaces
    • To check whitspaces, use s.isBlank() (jdk11+)
• Regex
  • replaceFirs() and replaceAll() takes regex as first param and string as second
  • [^ negates the expression String regex = "[^a-zA-Z0-9]"; s = s.replaceAll(regex,"");