String s=”str123str”;

String hello=s.replace(“str”,”hello”);

System.out.println(“hello:+hello);//输出结果：hello123hello

 

String s1=”str123st.r”;

String hello1=s1.replace(“\\.”,””);//\\进行转义

System.out.println(“hello1:+hello1);//输出结果：str123str

 

String s2=”str123str”;

String hello2=s.replaceFirst(“str”,”hello”);

System.out.println(“hello2:+hello2);//输出结果：hello123str