130.txt

Java 2实用教程（第三版） 清华大学出版社 （编著 耿祥义 张跃平） 例子源代码 第五章

第五章	字符串
例子1
class Example5_1
{  public static void main(String args[])
    {  String s1,s2;
       s1=new String("we are students");
       s2=new String("we are students");
       System.out.println(s1.equals(s2));    
       System.out.println(s1==s2);          
       String s3,s4; 
       s3="how are you";
       s4="how are you"; 
       System.out.println(s3.equals(s4));    
       System.out.println(s3==s4);    
    }
}
例子2
class Example5_2 
{   public static void main(String args[])
    {  int number=0; 
       String s="student;entropy;engage,english,client";
       for(int k=0;k<s.length();k++)
        {  if(s.regionMatches(k,"en",0,2))
             {  number++;
             }
         } 
       System.out.println("number="+number);
    }
}
例子3
class Example5_3 
{  public static void main(String args[]) 
{  String a[]={"door","apple","Applet","girl","boy"};
       for(int i=0;i<a.length-1;i++) 
          { for(int j=i+1;j<a.length;j++) 
            {  if(a[j].compareTo(a[i])<0) 
               {   String temp=a[i];
                   a[i]=a[j];
                   a[j]=temp;
                }
            } 
         }
      for(int i=0;i<a.length;i++) 
         {  System.out.print("  "+a[i]);
         }
    }
}
例子4
class Example5_4
{  public static void main(String args[])
   {   String path="c:\\myfile\\2000\\result.txt";
       int index=path.lastIndexOf("\\");
       String fileName=path.substring(index+1);
       String newName=fileName.replaceAll(".txt",".java");
       System.out.println(path);
       System.out.println(fileName);
       System.out.println(newName); 
   }
}

例子5
public class Example5_5
{  public static void main(String args[]) 
   {  double n,sum=0,item=0;
      boolean computable=true; 
      for(int i=0;i<args.length;i++) 
        { try{  item=Double.parseDouble(args[i]);
                sum=sum+item;
             }
          catch(NumberFormatException e)
             {  System.out.println("您键入了非数字字符:"+e);
                computable=false;
             }
        }
     if(computable)
        { n=sum/args.length;
          System.out.println("平均数:"+n);
        } 
     int number=123456;
     String binaryString=Long.toBinaryString(number);
     System.out.println(number+"的二进制表示:"+binaryString);
     System.out.println(number+"的十六进制表示:"+Long.toString(number,16));
     String str="1110110";
     int p=0,m=0;
     for(int i=str.length()-1;i>=0;i--) 
     {   char c=str.charAt(i);
         int a=Integer.parseInt(""+c);
         p=p+(int)(a*Math.pow(2,m));
         m++;
     }
     System.out.println(str+"的十进制表示:"+p);
  }
}
例子6
import java.util.Date;
import java.awt.*;
public class Example5_6
{  public static void main(String args[])
   {  Date date=new Date();
      Button button=new Button("确定");
      System.out.println(date.toString());
      System.out.println(button.toString());  
   }
}
例子7
import java.util.*;
public class Example5_7 
{  public static void main(String args[])
   {  String s="I am Geng.X.y,she is my girlfriend";
StringTokenizer fenxi=new StringTokenizer(s," ,"); 
      int number=fenxi.countTokens();
      while(fenxi.hasMoreTokens()) 
       {  String str=fenxi.nextToken();
          System.out.println(str);
          System.out.println("还剩"+fenxi.countTokens()+"个单词");
       }
     System.out.println("s共有单词："+number+"个");
   } 
}
例子8
class Example5_8 
{  public static void main(String args[])
   {  char c[],d[];
      String s="巴西足球队击败德国足球队";
      c=new char[2];
      s.getChars(5,7,c,0);
      System.out.println(c);
      d=new char[s.length()];
      s.getChars(7,12,d,0);
      s.getChars(5,7,d,5);
      s.getChars(0,5,d,7);
      System.out.println(d);
   }
}
例子9
class Example5_9 
{  public static void main(String args[]) 
   {  String s="清华大学出版社";
      char a[]=s.toCharArray();
      for(int i=0;i<a.length;i++)
        {  a[i]=(char)(a[i]^'t');
        }
String secret=new String(a);
System.out.println("密文:"+secret);
      for(int i=0;i<a.length;i++)
       {  a[i]=(char)(a[i]^'t');
       }
String code=new String(a);  
  System.out.println("原文:"+code);
   }
}
例子10
public class Example5_10
{  public static void main(String args[])
   {  byte d[]="你我他".getBytes();           
      System.out.println("数组d的长度是(一个汉字占两个字节):"+d.length);
      String s=new String(d,0,2);
      System.out.println(s);
   }
}
例子11
class Example5_11
{ public static void main(String args[ ])
  { StringBuffer str=new StringBuffer("62791720");
    str.insert(0,"010-");
    str.setCharAt(7 ,'8'); 
    str.setCharAt(str.length()-1,'7');
    System.out.println(str); 
    str.append("-446");
    System.out.println(str);
    str.reverse();
    System.out.println(str);
  }
}
例子12
public class Example5_12
{  public static void main (String args[ ])
   {  
      String regex="\\w{1,}@\\w{1,}\56\\w{1,}" ;
      String str1="[e-mail]";
      String str2="li@[e-mail]";
      if(str1.matches(regex))
      {  System.out.println(str1+"是一个Email地址"); 
      }
      else
      { System.out.println(str1+"不是一个Email地址"); 
      }
      if(str2.matches(regex))
      {  System.out.println(str2+"是一个Email地址"); 
      }  
      else
      { System.out.println(str2+"不是一个Email地址"); 
      }
   }
}