public void Ch() {

String ch1;

Scanner x = new Scanner(System.in);

ch1 = x.nextLine();

char[] cha = ch1.toCharArray();

//转换成数组

// 开始判断大小字符和数字

for (int i = 0; i < cha.length; i++) {

if (cha[i] < '9' && cha[i] > '0' || cha[i] < 'a') {

System.out.println(cha[i]);

}

}

}

public void RanC() {

char[] ch = new char[5];

char start = '0';

char end = 'z' + 1;

for (int i = 0; i < ch.length; i++) {

while (true) {

char s = (char) (Math.random() * (end - start) + start);

if (Character.isLetter(s) || Character.isDigit(s)) {

ch[i] = s;

break;

}

}

}

for (char c : ch) {

System.out.println(c);

}

}

public String randomString(int k) {

char[] sa = new char[k];

for (int i = 0; i < k; i++) {

while (true) {

char x = (char) (Math.random() * 'z' + 1);

if (Character.isLetter(x) || Character.isDigit(x)) {

sa[i] = x;

break;

}

}

}

String s = new String(sa);

return s;

}

public void RS() {

//创建一个长度是8的字符串数组

//使用8个长度是5的随机字符串初始化这个数组

//对这个数组进行排序，按照每个字符串的首字母排序(无视大小写)

//

//注1： 不能使用Arrays.sort() 要自己写

//注2： 无视大小写，即 Axxxx 和 axxxxx 没有先后顺序

String[] Sa = new String[8];

for (int i = 0; i < Sa.length; i++) {

Sa[i] = randomString(5);

}

for (int i = 0; i < Sa.length; i++) {

for (int j = 0; j < Sa.length - 1 - i; j++) {

if (Character.toLowerCase(Sa[j].charAt(0)) >= Character.toLowerCase(Sa[j + 1].charAt(0))) {

String temp = Sa[j + 1];

Sa[j + 1] = Sa[j];

Sa[j] = temp;

}

}

}

for (String x : Sa) {

System.out.println(x);

}

}

/*1. 生成一个长度是3的随机字符串，把这个字符串作为当做密码

public void secret() {

String st = randomString(3);

System.out.println(st);

char[] ss = st.toCharArray();

char[] guess = new char[3];

for (int i = 0; i < ss.length; i++) {

for (char j = 0; j < 'z'; j++) {

if (j == ss[i]) {

guess[i] = j;

}

}

}

String m = new String(guess);

System.out.println(m);

}

//

public void LetterC() {

String n = " i am bAt man ";

String t = n.trim();

String[] cc = t.split(" ");

for (int i = 0; i < cc.length; i++) {

String m = cc[i];

char z = Character.toUpperCase(m.charAt(0));

String a = m.substring(1);

String nn = a.toLowerCase();

String b = z + nn;

cc[i] = b;

}

for (String x : cc) {

System.out.println(x);

}

}

public void Rkl() {

String rkl = "peter piper picked a peck of pickled peppers";

String[] duanc = rkl.split(" ");

int num = 0;

for (int i = 0; i < duanc.length; i++) {

if (duanc[i].charAt(0) == 'p') {

num++;

}

}

System.out.println(num);

}

public void GU() {

String w = "dsfadgjarjg";

char[] d = w.toCharArray();

for (int i = 0; i < d.length; i++) {

if (i % 2 == 0) {

d[i] = Character.toUpperCase(d[i]);

}

}

String www = new String(d);

System.out.println(www);

}

public void LW() {

String ss = "adlfjla";

char[] ars = ss.toCharArray();

char x = Character.toUpperCase(ss.charAt(ars.length - 1));

ars[ars.length - 1] = x;

String m = new String(ars);

System.out.println(m);

}

public void LT() {

String two = "Nature has given us that two ears, two eyes, and but one tongue, to the end that we should hear and see more than we speak";

int lt = two.lastIndexOf("two");

char[] cc = two.toCharArray();

char atwo = Character.toUpperCase(two.charAt(lt));

cc[lt] = atwo;

String z = new String(cc);

System.out.println(z);

}

public void RepeatCount() {

String[] strings = new String[100];

for (int i = 0; i < strings.length; i++) {

strings[i] = randomString(2);

}

int count = 0;

for (String string : strings) {

System.out.print(string + " ");

count++;

if (count % 20 == 0) {

System.out.println();

}

}

String[] repeatstring = new String[100];

int repeattimes = 0;

boolean flag = false;

for (int i = 0; i < strings.length; i++) {

for (int j = 0; j < repeatstring.length; j++)

if (strings[i].equals(repeatstring[j])) {

flag = true;

break;

}

if (flag) // 如果repeat数组中已经存在该字符串，就终止本次循环

continue;

for (int k = i + 1; k < strings.length; k++) {

if (strings[i].equals(strings[k])) {

repeatstring[repeattimes] = strings[k];

repeattimes++;

break;

}

}

}

System.out.println("总共有 " + repeattimes + " 种重复的字符串");

if (repeattimes == 0) {

System.out.println("没有重复");

} else {

System.out.println("分别是：");

for (int z = 0; z < repeattimes; z++) {

System.out.print(repeatstring[z] + " ");

}

}

}

public void StringB() {

String tenbit = randomString(10);

long x = System.currentTimeMillis();

for (long i = 0; i < 100000; i++) {

tenbit += randomString(10);

}

long y = System.currentTimeMillis();

System.out.println(y-x);

StringBuffer tenbit2 = new StringBuffer(randomString(10));

long x2 = System.currentTimeMillis();

for (long i = 0; i < 100000; i++) {

tenbit2.append(randomString(10));

}

long y2 = System.currentTimeMillis();

System.out.println(y2-x2);

}

public static void main(String[] args) {

Start2 start2 = new Start2();

start2.StringB();

}

}