java 数组转换成字符串 类似 js array的join

public static String join( Object[] o , String flag ){
	    StringBuffer str_buff = new StringBuffer();
	  
	    for(int i=0 , len=o.length ; i<len ; i++){
	        str_buff.append( String.valueOf( o[i] ) );
	        if(i<len-1)str_buff.append( flag );
	    }
	 
	    return str_buff.toString(); 
	}