Java面向对象_常用类库api

StringBuffer

例:

 public class StringBufferDemo {

     /**
      * @param args
      */
     public static void main(String[] args) {
         // TODO Auto-generated method stub
         //使用String的写法连接字符串，比较占内存
         String s="hello";
         String ss=s+"world";
         for(int i=0;i<10;i++){
             s+="hello"+i;
         }
         System.out.println(s);
         //StringBuffer
         StringBuffer sb=new StringBuffer(100);//带容量
         for(int i=0;i<10;i++){
             sb.append(i);
         }
         System.out.println(sb);
     }

 }

程序国际化Locale类

Locale(String language)

Locale(String language,String country)

通过静态方法创建Locale:

getDefault()

 public class LocaleDemo {

     /**
      * @param args
      */
     public static void main(String[] args) {
         // TODO Auto-generated method stub
         Scanner input=new Scanner(System.in);
         Locale locale=Locale.CHINA;
         locale.getCountry();

         Locale locale2=new Locale("en","US");

         ResourceBundle rb=ResourceBundle.getBundle("com.vince.info",locale);
         System.out.println(rb.getString("welcome"));
         System.out.println(rb.getString("input.username"));
         String username=input.next();
         System.out.println(rb.getString("input.psw"));
         String password=input.next();
         if("abc".equals(username)&&"123".equals(password)){

             String info=MessageFormat.format(rb.getString("info"),"abc");//处理动态文本
             System.out.println(info);
         }
     }

 }

实现国际化，要File->new->File