java截取字符串并拼接

public static void main(String[] args) {
String sendContent = "请查收:www.baidu.com";

//查询字符串最后一个冒号的位置
int index=sendContent.lastIndexOf(":");

//截取
String qian = sendContent.substring(0, index);
String houb = sendContent.substring(index);

//拼接
String all= qian.concat("http").concat(houb);

System.out.println(houb);
System.out.println(qian);
System.out.println(all);
}