java字符串空格替换

String s = "我爱  我的祖 国"; 

System.out.println(s.replaceAll(" ", ",").trim());
//处理后输出:我爱,五星红旗
String regEx = "[' ']+"; // 一个或多个空格  
Pattern p = Pattern.compile(regEx);  
Matcher m = p.matcher(s);
System.out.println(m.replaceAll(",").trim());

System.out.println(s.lastIndexOf(" ")+1);

System.out.println(s.substring(s.lastIndexOf(" ")+1, s.length()));