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