StringBuffer buf = new StringBuffer("Java");
    // Append
    buf.append(" Almanac v1/");      // Java Almanac v1/
    buf.append(3);                   // Java Almanac v1/3
   
    // Set
    int index = 15;
    buf.setCharAt(index, .);       // Java Almanac v1.3
   
    // Insert
    index = 5;
    buf.insert(index, "Developers ");// Java Developers Almanac v1.3
   
    // Replace
    int start = 27;
    int end = 28;
    buf.replace(start, end, "4");    // Java Developers Almanac v1.4
   
    // Delete
    start = 24;
    end = 25;
    buf.delete(start, end);          // Java Developers Almanac 1.4
   
    // Convert to string
    String s = buf.toString();
比较字符串
String s1 = "a";
    String s2 = "A";
    String s3 = "B";
   
    // Check if identical 监测是否一致
    boolean b = s1.equals(s2);           // false
   
    // Check if identical ignoring case
    b = s1.equalsIgnoreCase(s2);         // true
   
    // Check order of two strings 监测两个字符串的顺序
    int i = s1.compareTo(s2);            // 32; lowercase follows uppercase
    if (i < 0) {
        // s1 precedes s2
    } else if (i > 0) {
        // s1 follows s2
    } else {
        // s1 equals s2
    }
   
    // Check order of two strings ignoring case
    i = s1.compareToIgnoreCase(s3);      // -1
    if (i < 0) {
        // s1 precedes s3
    } else if (i > 0) {
        // s1 follows s3
    } else {
        // s1 equals s3
    }
   
    // A string can also be compared with a StringBuffer;
    StringBuffer sbuf = new StringBuffer("a");
    b = s1.contentEquals(sbuf);          // true
判断一个字符串中是否包含另外一个字符串
String string = "Madam, I am Adam";
   
    // Starts with
    boolean  b = string.startsWith("Mad");  // true
   
    // Ends with
    b = string.endsWith("dam");             // true
   
    // Anywhere
    b = string.indexOf("I am") > 0;         // true
   
    // To ignore case, regular expressions must be used
   
    // Starts with
    b = string.matches("(?i)mad.*");
   
    // Ends with
    b = string.matches("(?i).*adam");
   
    // Anywhere
    b = string.matches("(?i).*i am.*");
获取制定字符串中的子串
int start = 1;
    int end = 4;
    String substr = "aString".substring(start, end);   // Str
查询指定字符串中的子串以及字母的位置
String string = "madam, i am Adam";
   
    // Characters
   
        // First occurrence of a c
        int index = string.indexOf(a);    // 1
   
        // Last occurrence
        index = string.lastIndexOf(a);    // 14
   
        // Not found
        index = string.lastIndexOf(z);    // -1
   
    // Substrings
   
        // First occurrence
        index = string.indexOf("dam");      // 1
   
        // Last occurrence
        index = string.lastIndexOf("dam");  // 13
   
        // Not found
        index = string.lastIndexOf("z");    // -1
取代制定字符的函数操作
// Replace all occurrences of a with o
    String newString = string.replace(a, o);
取代制定字符串的操作
static String replace(String str, String pattern, String replace) {
        int s = 0;
        int e = 0;
        StringBuffer result = new StringBuffer();
   
        while ((e = str.indexOf(pattern, s)) >= 0) {
            result.append(str.substring(s, e));
            result.append(replace);
            s = e+pattern.length();
        }
        result.append(str.substring(s));
        return result.toString();
    }
转变字符串的大小写
// Convert to upper case
    String upper = string.toUpperCase();
   
    // Convert to lower case
    String lower = string.toLowerCase();
Converting a Primitive Type Value to a String
// Use String.valueOf()
    String s = String.valueOf(true);     // true
    s = String.valueOf((byte)0x12);      // 18
    s = String.valueOf((byte)0xFF);      // -1
    s = String.valueOf(a);             // a
    s = String.valueOf((short)123);      // 123
    s = String.valueOf(123);             // 123
    s = String.valueOf(123L);            // 123
    s = String.valueOf(1.23F);           // 1.23
    s = String.valueOf(1.23D);           // 1.23
   
    // Use +
    s = ""+true;                         // true
    s = ""+((byte)0x12);                 // 18
    s = ""+((byte)0xFF);                 // -1
    s = ""+a;                          // a
    s = ""+((short)123);                 // 123
    s = ""+123;                          // 123
    s = ""+123L;                         // 123
    s = ""+1.23F;                        // 1.23
    s = ""+1.23D;                        // 1.23
Converting Between Unicode and UTF-8
try {
        // Convert from Unicode to UTF-8
        String string = "abc\u5639\u563b";
        byte[] utf8 = string.getBytes("UTF-8");
   
        // Convert from UTF-8 to Unicode
        string = new String(utf8, "UTF-8");
    } catch (UnsupportedEncodingException e) {
    }