String (Java.lang.String)

Immutable Datatype

Instantiate

String s;

Methods (s)

• contains() - returns true/ false if subString is present in String

  s.contains(String subString);

• indexOf() - returns the index of the subString/ character

  int n = s.indexOf(String subString);

  int n = s.indexOf(char ch);

• replace() - replace old char wth new char for all occurance of old char

  s.replace(char old,char new);
  • replaceFirst() - replace old char wth new char for first occurance of old char
    s.replaceFirst(char old,char new);

• matches() - tells whether or not the string matches the given regular expression, returns boolean

  s.matches('regex');

• split() - split string at matching regex into string array

  String[] array = s.split('regex');

• startsWith() - method determines whether a string begins with the characters of a specified string, returning true or false

  s.startsWith(String prefix);

  s.startsWith(String prefix,int position); // starts searching from the position index

• endsWith() - method determines whether a string ends with the characters of a specified string, returning true or false

  s.endsWith(String suffix);

• toLowerCase() - converts string to lowercase string

  String str = s.toLowerCase();

• toUpperCase() - converts string to uppercase string

  String str = s.toUpperCase();

• trim() - removes leading and training whitespace

  String str = s.trim();

• join() - returns string joined with given delimiter

  String str = s.join(CharSequence delimiter,CharSequence elements); //elements here are strings

• compareTo() - returns int value after comparing two strings lexographically

  int n = s1.compareTo(s2);

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• Character.isLetter() - returns true/false if char is Letter
  Character.isLetter(char ch);
• Character.isDigit() - returns true/false if char is digit
  Character.isDigit(char ch);
• Character.isWhitespace() - returns true/false if char is space
  Character.isWhitespace(char ch);
• Character.isUpperCase() - returns true/false if char is a Uppercase letter
  Character.isUpperCase(char ch);
• Character.isLowerCase() - returns true/false if char is a Lowercase letter
  Character.isLowerCase(char ch);