Lập trình hướng đối tượng trong java (Phần 5) docx

         1 LẬP TRINH HƯỚ NG ĐÔ ́ I TƯỢNG TRONG JAVA phần 5 LỚ P STRING VÀ NUMBER I.           .                 (Java          ),        ,            .                  ?     ,    ,                     ,  .lang.                . II.   STRINGBUFFER Trong g.                  :    StringBuffer,   ,   ,      . StringBuffer        . V d :                    . public class ReverseString { public static String reverse(String source) { int i, len = source.length();          2 StringBuffer dest = new StringBuffer(len); for (i = (len - 1); i >= 0; i ) dest.append(source.charAt(i)); return dest.toString(); } } 1. Lơ ́ p String To mt đi tưng        .        ba        ,      .        ,   String s = new String(); String s = new String("Gobbledygook.");     : String s = "Hola Mundo"; - : String() String(byte bytes[]) String(byte bytes[],int startIndex, int numChars) String(char chars[]) String(char chars[], int startIndex, int numChars) String(String s) String(StringBuffer s) V d : byte b[] = {65, 66, 67, 68, 69, 70}; String s1 = new String(b); // K    DEF String s2 = new String(b,2,3); // K               3 String s3 =   (c); // Kh String s4 = new String(c,2,3); //          String s5 = new String(s2); // T3          s2  - int length() : cho chi int len = source.length(); int len = "Goodbye Cruel World".length(); - char charAt(int index) : t char c = source.charAt(1);  //G - boolean equals(String object) : ki,         () v= = .              .  = = so s2             . String s1  String s2 = new String(s1); // t 2  1,      //          : s1 equals s2 : true s1 = = s2 : false - int compareTo(String str) : so s2 , :  < 0 :     > 0 :     = 0 :   - int indexOf(int character) :  (c    )  character int lastIndexOf(int character)          4 - int indexOf(int character, int from) :  (c   )  character,        from   (  ) int lastIndexOf(int character, int from) - int indexOf(String string) : (c   ) string int lastIndexOf(String string) - int indexOf(String string, int from) :  (c   )  string,        from   (  ) int lastIndexOf(String string, int from) - String subString(int startIndex, int endIndex) :              -1,          String org   result = org.subString(8); - String replace(char orginal, char replacement) :         // Cho s   - String trim() :            - String toLowerCase() :        - String toUpperCase() :       String upper = s.toUpperCase(); - Ton tư ̉ + :  ,        , String s1 = "two"; System.out.println("one" + s1 + "three"); System.out.println("Word v. " + 9+7); V                  ,  ,        +,    Java        s ,        ,       sang StringBuffer public class ReverseString {          5 public static String reverse(String source) { int i, len = source.length();  for (i = (len - 1); i >= 0; i ) dest = dest + source.charAt(i); return dest; } } - static String valueOf(object/var x) : , tr  V d :          , : System.out.println(String.valueOf(Math.PI)); 2. Lp StringBuffer To mt đi tưng StringBuffer           : StringBuffer() : 16  StringBuffer(int length) :  V d : StringBuffer dest = new StringBuffer(25); Cc phương thc thưng dng ca lp StringBuffer - int length() : cho chi - char charAt(int index) : tex - void setCharAt(int index, char ch) :     ,  - StringBuffer append(object/var x) :              .               int a = 20; StringBuffer sb = new StringBuffer(40);   (); - StringBuffer insert(int index, object/var x) : ch x StringBuffer sb = new StringBuffer("I Java!");          6 sb.insert(3, "like "); System.out.println(sb); //  - StringBuffer reverse() :          StringBuffer sb = new StringBuffer("I Java!"); sb.reverse(); - StringBuffer delete(int startIndex, int endIndex) : x   endIndex-1 - StringBuffer deleteCharAt(int index) :  - StringBuffer subString(int startIndex, int endIndex) :   -1,         - StringBuffer replace(int startIndex, int endIndex, String str) :     dex-1   .lang.String and java .lang.       .          1 LẬP TRINH HƯỚ NG ĐÔ ́ I TƯỢNG TRONG JAVA phần 5 LỚ P STRING VÀ NUMBER I.     .                 (Java          ),       .            . II.   STRINGBUFFER Trong g.                 