import java.util.Random;
public class Demo1 {public static void main(String[] args) {// 产生随机字符串 a=97 b=98 c=99String sourceStr = "";String destStr = "";Random random = new Random();for (int i = 0; i < 20; i++) {//ASCII字符集a=97 b=98 c=99sourceStr += (char) (random.nextInt(26) + 97);}System.out.println(sourceStr);for (int i = 0; i < sourceStr.length(); i++) {char c = sourceStr.charAt(i);if (destStr.indexOf(c) == -1) {destStr += c;} else {continue;}}System.out.println(destStr);}}

public class StringBufferDemo {public static void main(String[] args) {StringBuffer sb = new StringBuffer();System.out.println(sb.length());System.out.println(sb.capacity());// StringBuffer sb1 = new StringBuffer("abc");// System.out.println(sb1.length());// System.out.println(sb.capacity());//增加，修改，删除，查询//增加数据append(追加) insert(插入)sb.append("xyz");System.out.println(sb.toString());sb.append("abc");System.out.println(sb.toString());sb.insert(3, "xxx");System.out.println(sb.toString());//修改 replacesb.replace(2, 5, "oooo");System.out.println(sb.toString());//setCharAt:修改某个位置的字符sb.setCharAt(2, '9');System.out.println(sb.toString());//删除sb.delete(2, 5);System.out.println(sb.toString());sb.deleteCharAt(3);System.out.println(sb.toString());//搜索 abaSystem.out.println(sb.indexOf("x"));}}

import java.util.Scanner;public class StringBufferDemo1 {public static void main(String[] args) {Scanner sc = new Scanner(System.in);System.out.println("请输入一个字符串:");String str = sc.nextLine();StringBuffer sb = new StringBuffer(str);sb.reverse();if (str.equals(sb.toString())) {System.out.println("是一个回文字符串");} else {System.out.println("不是一个回文字符串");}}}

    @Overridepublic String toString() {return "name=" + name + "\tage=" + age + "\taddress=" + address;}@Overridepublic boolean equals(Object obj) {if (obj instanceof Person) {Person other = (Person) obj;if (this.name.equals(other.getName()) && this.age == other.getAge()&& this.address.equals(other.getAddress())) {return true;} else {return false;}}return false;}