java的String和StringBuilder方法

String s1="hello lxx";
    String s2=new String("fff df");
    System.out.println(s1.length());
    System.out.println(s1.substring(0, 2));
    System.out.println(s1.equals(s2));
    System.out.println(s1.charAt(3));
    System.out.println(s1.replace("o","r"));
    System.out.println(s1.indexOf("l"));
    StringBuilder s3=new StringBuilder("hello nihao");
    System.out.println(s3.append("a"));
    //    打印s3的容量capacity()
    System.out.println(s3.capacity());
    //在2的位置插入b字符串
    System.out.println(s3.insert(2, "b"));
    System.out.println(s3.delete(2, 3));
    //reverse反转
    System.out.println(s3.reverse());

运行结果

9
he
false
l
hellr lxx
2
hello nihaoa
27
hebllo nihaoa
hello nihaoa
aoahin olleh