JAVA String

1. Convert to String
   
   //Integer to String
   int number = 1234;
   String strtoint = Integer.toString(number); //1234
   strtoint = "" + number; //1234
   //Double to String
   strtoint = Double.toString(number); //1234.0
   //Long to String
   strtoint = Long.toString(number); //1234
   //Flot to String
   strtoint = Float.toString(number); //1234.0
   //Binary to String
   strtoint = Integer.toBinaryString(number); //10011010010
   strtoint = Integer.toString(number,2); //10011010010
   //Hexadecimal to String
   strtoint = Integer.toHexString(number); //4d2
   strtoint = Integer.toString(number,16); //4d2
2. Convert from String
   
   //String to Integer
   String number = "1234";
   int inumber = Integer.valueOf(number).intValue();
   inumber = Integer.parseInt(number);
   //String to Double
   Double dnumber = Double.valueOf(number).doubleValue();
   dnumber = Double.parseDouble(number);
   //String to Long
   Long lnumber = Long.valueOf(number).longValue();
   lnumber = Long.parseLong(number);
   //String to Flot
   Float fnumber = Float.valueOf(number).floatValue();
   fnumber = Float.parseFloat(number);
   //ASCII Code
   char c = "D";
   inumber = (int) c; //66
   String test = "ABCD";
   for( int i = 0; i < test.length(); ++i ) {
     c = test.charAt( i );
     inumber = (int) c;
     System.out.println(inumber);
   }
3. Tokenizer
   
   import java.util.StringTokenizer;
   StringTokenizer st = new StringTokenizer("this is a test tokenized");
   //StringTokenizer st = new StringTokenizer("this is a test tokenized"," ");
   while(st.hasMoreTokens()){
     System.out.println(st.nextToken());
   }
   It is recommended that anyone seeking this functionality use the split method of String or the java.util.regex package instead.
   
   String[] result = "this is a test tokenized".split("\\s");
   for (int x=0; x < result.length; x++)
     System.out.println(result[x]);
4. Split
   
   String str = "Day-Night-Soft-Blog";
   java.util.Arrays.toString(str.split("-")); //[Day, Night, Soft, Blog]
   The special character must be escaped with a "\", but in java "\" is also a special character, so need to escape it again with another "\\".
   
   String[] arrLines = null;
   str = "Day.Night.Soft.Blog";
   //wrong way split
   arrLines = str.split(".");
   //java.util.Arrays.toString(arrLines); //[]
   arrLines = str.split("\\.");
   ava.util.Arrays.toString(arrLines); //[Day, Night, Soft,Blog] good way split
   str = "Day|Night|Soft|Blog";
   //wrong way split
   //java.util.Arrays.toString(str.split("|")); //[, D, a, y, |, N, i, g, h, t, |, S, o, f, t, |, B, l, o, g]
   java.util.Arrays.toString(str.split("\\|")); //[Day, Night, Soft, Blog] good way split
   //to include empty strings
   str = "Day;Night;Soft;Blog;;java;;;";
   arrLines = str.split("\\;");
   //The output does not contain the empty strings between the ";" separator.
   //java.util.Arrays.toString(arrLines); //[Day, Night, Soft, Blog, , java]
   //to keep empty strings
   arrLines = str.split("\\;", -1);
   java.util.Arrays.toString(arrLines); //[Day, Night, Soft, Blog, , java, , ,]
   //muliple split
   str = "day+night*s-soft*s^2-blog-221";
   arrLines = str.split("[-+*]", -1);
   java.util.Arrays.toString(arrLines); //[day, night, s, soft, s^2, blog, 221]
5. String Builder
   
   StringBuilder sb = new StringBuilder(100);
   for (int i = 0; i < 50; i++)
       sb.append(i).append('\n');
6. Trim
   
   String str = " Day-Night-Soft-Blog ";
   str.trim(); //Day-Night-Soft-Blog;
7. Regex Pattern
   
   String starts with digit or upper case
   import java.util.regex.Pattern;
   String str ="daynightsoft123";
   Pattern.compile("^[A-Z0-9]").matcher(str).find(); //false
   str ="123daynightsoft";
   Pattern.compile("^[A-Z0-9]").matcher(str).find(); //true
   str ="Daynightsoft123";
   Pattern.compile("^[A-Z0-9]").matcher(str).find(); //true
8. Replace
   
   "Daynightsoft*s".replace( '*', '\'' ); //Daynightsoft's
   \d digit, \w work token, special charaters
   String str ="@*1#^2$@!34#5ajs67>?<{8_(9SKJDH";
   str.replaceAll("\\W", ""); //12345ajs678_9SKJDH
   str.replaceAll("\\w", ""); //@*#^$@!#>?<{(
   str.replaceAll("\\D", ""); //123456789
   str.replaceAll("\\d", ""); //@*#^$@!#ajs>?<{_(SKJDH
   "090909".replaceAll("(\\d\\d)", "XX$1"); //XX09XX09XX09
9. Regex Matcher
   
   import java.util.regex.Matcher;
   import java.util.regex.Pattern;
   public static String matcherFirstWordUpper(String str) {
   

   StringBuffer sb = new StringBuffer();

   Matcher m = Pattern.compile("([a-z])([a-z]*)",Pattern.CASE_INSENSITIVE).matcher(str);

   while (m.find()) {

   m.appendReplacement(sb, m.group(1).toUpperCase() + m.group(2).toLowerCase()) ;

   }

   return m.appendTail(sb).toString();

   }
   
   firstWordUpper(" #100day-night-soft-blogs"); //  #100Day-Night-Soft-Blogs
   firstWordUpper("GOOgle andRiod"); //Google Andriod
   frstWordUpper("honda o'daniel & toyoto mcmillan"); //Honda O'Daniel & Toyoto Mcmillan
10. Format
    
    String s = String.format("It is a %s blog(%s)", "Java's String", "makdns.blogspot.com");
    System.out.println(s); //It is a Java's String blog(makdns.blogspot.com)
    Object obj[] = {"Java's String", "makdns.blogspot.com", java.util.Calendar.getInstance()};
    String s = String.format("It is a %s at %s blog (%3$tm %3$td, %3$tY)", obj);
    System.out.println(s); //It is a Java's String at makdns.blogspot.com blog (03 22, 2011)
    System.out.println(String.format("%4$s %3$s %2$2s %1$2s", "a", "b", "c", "d")); //d c b a
    
    Printf method (behavior is based on the C sprintf) - to write a formatted string to this output stream using the specified format string and arguments.
    
    System.out.printf("It is a %s blog(%s)", "Java's String", "makdns.blogspot.com");