public final class String
implements java.io.Serializable, Comparable<String>, CharSequence {
/** The value is used for character storage. */
private final char value[];
public class StringMethodTest1 {
public static void main(String[] args) {
String s = "HelloWorld";
// int length() 返回此字符串的长度
System.out.println(s.length()); // 10
// char charAt(int index) 返回 char指定索引处的值
System.out.println(s.charAt(1)); // e