자바 string 클래스 방법 깊이 분석

 
  
import java.nio.charset.Charset; 
  
import java.nio.charset.UnsupportedCharsetException; 
  
import java.util.Locale; 
  
import java.util.Date; 
  
import java.util.regex.PatternSyntaxException; 
   
  
import javax.xml.crypto.Data;
 
  
public class Stringxuexi {
  public static void main(String[] argc)
  {
    //charAt(int index)   index  Unicode  
    String strCom = "JAVA    ";
    System.out.println(strCom.charAt(4));

    //codePointAt(int index)   index    Unicode   
    strCom = "I like JAVA ,too";
    System.out.println(strCom.codePointAt(8));

    //codePointBefore   index-1    Unicode   
    System.out.println(strCom.codePointBefore(2));

    //codePointCount(int beginIndex,int endIndex)               Unicode      
    System.out.println(strCom.codePointCount(0, 3));

    
    //compareTo(String str)
    //         ，                 ，      ，           
    //               ，  k         ，                k 
    //  char   ，             ，              
    System.out.println(strCom.compareTo("I like PHP"));
    System.out.println(strCom.compareTo("I like JAVA too"));

    //compareToIgnoreCase(String str)                
    System.out.println(strCom.compareToIgnoreCase("I Like PHP"));

    //concat(String str)                 ，           0，
    //       ，        String  
    System.out.println(strCom.equals(strCom.concat("")));
    System.out.println(strCom.concat(strCom));

    //contains（CharSequence s)            char   
    System.out.println(strCom.contains("JAVA"));

    //valueOf(char []data)     ，               
    char [] array={' ',' '};
    System.out.println(String.valueOf(array));

    //valueOf(char[] data,int offset,int count)         offset    count   
    //      
    System.out.println(String.valueOf(array, 0, 1));

    //endwith(String suffix)               
    System.out.println(strCom.endsWith("JAVA"));

    //equals(object obj)              String  String  ，   true，  false
    System.out.println(strCom.equals("I like JAVA"));

    //equalsIgnoreCase(String anotherString) //               ，   equals         
    System.out.println(strCom.equalsIgnoreCase("I Like JAva"));

    //format(String format,Object ...args)                               
    //%d          
    //%o          
    //%x %X           

    System.out.println(String.format("%e %x %o %d %a %% %n", 15.000,15,15,15,15.0));

    
    //format(Locale l,String format,Object ... args)
    //                              
    //%te         
    //%tb            
    //%tB            
    //%tA             
    //%ta             
    //%tc            
    //%tY 4   
    //%ty     
    //%tm   
    //%tj        
    //%td         
    Date date = new Date(); 
    Locale form = Locale.CHINA;
    String year = String.format(form, "%tY", date);
    String month    = String.format(form, "%tm", date);
    String day = String.format(form, "%td", date);
    System.out.println("   ： "+ year + " "+month+" "+day+" ");
    System.out.println(String.format(form, "%tc", date));

    //byte[] getBytes()       byte      
    byte[] str = strCom.getBytes();
    for (int i = 0;i < str.length;i++)
      System.out.print(str[i]+" ");

    //getBytes(Charset charset)
    //getBytes(String string)
    //              
    try {
      str = strCom.getBytes(Charset.defaultCharset());
      for (int i = 0; i < str.length; i++)
        System.out.println(str[i] + " ");
    } catch (UnsupportedCharsetException e) {
      // TODO: handle exception
      e.printStackTrace();
    }

    //getchars（int srcBegin,int srcEnd,char[] dst,int dstBegin)
    //                 
    char[] dst = new char[10];
    strCom.getChars(0, 10, dst, 0);
    for (int i = 0; i < dst.length;i++)
      System.out.print(dst[i]);
    System.out.println();

    //hashCode()             ，String            
    //s[0]*31^(n-1)+s[1]*31^(n-2)+...+s[n-1] 
    //       0
    System.out.println(strCom.hashCode());

    //indexOf(int ch)           ，ch     ，    ，  -1
    System.out.println(strCom.indexOf('A'));

    //indexOf(int ch,int fromIndex)    //                    
    //fromIndex    ，    ， 0  ，           ，   -1
    System.out.println(strCom.indexOf('A', 9));

    //indexOf(String str)
    //indexOf(String str,int fromIndex)
    //                     
    System.out.println(strCom.indexOf("JAVA"));

    //intern()                   
    //   intern   ，            String      ，         
    //              ，    String    
    //                                          。
    String strCom2 = new String("I like JAVA");
    System.out.println(strCom == strCom2);
    System.out.println(strCom.endsWith(strCom2));
    System.out.println(strCom.compareTo(strCom2));
    System.out.println(strCom.intern() == strCom2.intern());
    String s1 = new String("  ,Java   ");
    String s2 = new String("  ,") + "Java   ";
    System.out.println(s1==s2);
    System.out.println(s1.intern()==s2.intern());

    // indexOf，  fromIndex   ，   fromIndex     
    System.out.println(strCom.lastIndexOf('A'));
    System.out.println(strCom.lastIndexOf('A',10));
    System.out.println(strCom.lastIndexOf("JAVA"));
    System.out.println(strCom.lastIndexOf("JAVA", 10));

    //       
    System.out.println(strCom.length());

    //matchs(String regex)       
    try {
      String regex = "1234";
      System.out.println(regex.matches("//d{4}"));
      System.out.println(regex.replaceAll("//d{4}", "chen"));
      System.out.println(regex.replaceFirst("//d{4}", "chen"));
    } catch (PatternSyntaxException e) {
      // TODO: handle exception
      e.printStackTrace();
    }

    // offsetByCodePoints(int index,int codePointOffset)
    //      index   codePointOffset       
    System.out.println(strCom.offsetByCodePoints(7, 4));

    //             ,      true        
    System.out.println(strCom.regionMatches(true, 0, "I lIke", 0, 3));
    System.out.println(strCom.regionMatches(0, "I like", 0, 3));

    System.out.println(strCom.replace('A', 'a'));
    System.out.println(strCom.replace("JAVA", "PHP"));

    //String[] split(String regex,int limit)
    //                         ，limit         
    String[] info = strCom.split(" ,");
    for (int i = 0; i < info.length;i++)
      System.out.println(info[i]);

    info    = strCom.split(" ", 2);
    for (int i = 0; i < info.length;i++)
      System.out.println(info[i]);

    //startsWith(String prefix,int toffset)//           
    //toffset             false
    System.out.println(strCom.startsWith("I"));
    System.out.println(strCom.startsWith("I",-1));

    //CharSequeuece subSequeuece(int beginIndex,int endIndex)
    //          
    System.out.println(strCom.subSequence(2, 6));

    //String substring(int beginindex,int endIndex)
    //      
    System.out.println(strCom.substring(2));
    System.out.println(strCom.substring(2, 6));

    //toCharArray()         
    char[] str1 = strCom.toCharArray();
    for (int i = 0; i < str1.length;i++)
      System.out.print(str1[i]+" ");
    System.out.println();

    //toLowerCase(Locale locale)              /         
    System.out.println(strCom.toLowerCase());
    System.out.println(strCom.toUpperCase());
    System.out.println(strCom.toUpperCase(form));
    System.out.println(strCom.toLowerCase(form));

    //trim()            
    System.out.println(("    "+strCom).trim());

    //valueOf()                       
    System.out.println(String.valueOf(true));
    System.out.println(String.valueOf('A'));
    System.out.println(String.valueOf(12.0));
  }
}