Quick Java Strings

• General: the String class is defined in java.lang, and is pretty close to being a primitive datatype (such as int).
• Constructors:
  • String s = "Good";
  • String ss = {'A', 'B', 'C'};
  • char[] c = {'L', 'u', 'c', 'k'};
  • String sss = new String(c);
  The escape character is "\". Here are some escaped characters you may need:

  	\n = newline,  			\t = tab,
  	\\ = escape character itself,	\" = double quote
  	\' = single quote 		
  

• Methods:
  • boolean b = s.equals("good"); // b = false
  • b = s.equalsIgnoreCase("good"); // b = true
  • int i = s.length(); // i = 4
  • i = s.indexOf('o'); // i = 1
  • i = s.LastIndexOf('o'); // i = 2
  • i =s.indexOf("od"); // i = 2
  • String t = s.substring(2); // t = "od"
  • t = s.substring(0,2); // t = "Go"
  • t = s.concat(sss); // t = "GoodLuck"
  A special method is the "+" operator for Strings. This is the same as concat. E.g. "try " + "me!" = "try me!". This is useful if you need to enter very long strings, but you do not want your input file to have long strings:

  	System.out.println( "This is useful if you need "
  	+ "to enter very long strings, but you do not "
  	+ "want your input file to have long strings");
  

• Other methods:
char charAt(int index),
int compareTo(String s),
static String copyValueOf(char[] c),
boolean endsWith(String s),
boolean startsWith(String s, int offset),
byte[] getBytes(String s),
int hashCode(),
String replace(char oldc, char newc),
String toUpperCase()/toLowerCase(),
String trim(), (remove white spaces from both ends)
static String valueof(boolean b), ("true"/"false")
static String valueof(double d), (String rep of d)

• Strings are "immutable", and if you need efficient mutable strings, look at StringBuffer (also in java.lang).
• String API from sun documentation