package Blog1;

import java.util.Scanner;

public class Blog12 {
 public static void main(String[] args) {
 StringBuilder stringBuilder = new StringBuilder();
 StringBuffer stringBuffer = new StringBuffer();
 stringBuffer.append("a");

 for (int i = 0; i < 10; i++) {
 stringBuilder.append("a");
 }

 System.out.println(stringBuilder.append("a"));
 }

 public static void main16(String[] args) {
 String str = "";

 for (int i = 0; i < 10; i++) {
 str += "a";
 }
 System.out.println(str);
 }

 public static void main15(String[] args) {
 String str = "abcdefg";
 System.out.println(str);
 String ret = dans(str,3);
 System.out.println(ret);
 }

 public static String dans(String str, int n) {
 if(null == str || n <= 0 || n >= str.length()) {
 return null;
 }
 str = reverse(str,0,n-1);
 str = reverse(str,n,str.length()-1);
 str = reverse(str,0,str.length()-1);
 return str;
 }

 public static String reverse(String str, int begin, int end) {
 char[] value = str.toCharArray(); // 将字符串转为字节char[]数组,
 // 一个一个字符,取出后替换,
 while(begin < end) {
 char tmp = value[begin];
 value[begin] = value[end];
 value[end] = tmp;
 begin++;
 end--;
 }

 return new String(value); // 字符数组构造方法,创建字符串

 /* // 或者使用 String.copyValueOf() 将数组转为字符串返回
 return String.copyValueOf(value);
*/
 }



 public static void main14(String[] args) {
 String str = "hello world";
 int[] arrays = {1,2,3};

 System.out.println(str.length());
 System.out.println(arrays.length);
 }


 public static void main13(String[] args) {
 String str = "hello";
 String str2 = "";

 System.out.println(str.isEmpty());
 System.out.println(str2.isEmpty());
 }

 public static void main12(String[] args) {
 String str = "aaaAAA你好世界!!!";
 String ret = str.toLowerCase(); // 大写转小写
 System.out.println(ret);
 String ret2 = str.toUpperCase(); // 小写转大写
 System.out.println(ret2);

 }


 public static String func(String str) {
 String[] strings = str.split(" ");
 String tmp = "";
 for (String s:strings) {
 tmp += s;
 }

 return tmp;
 }

 public static void main11(String[] args) {
 Scanner scanner = new Scanner(System.in);

 while(scanner.hasNext()) {
 String str = scanner.nextLine();
 // 不可以使用next(),因为读取到空格就结束了,
 // nextLine(), 不可以于 nextInt()连接使用,nextLine()会读取到回车
 String ret = func(str);
 System.out.println(ret);
 }
 }



 public static void main10(String[] args) {
 String str = "Java-split#18";
 String[] strings = str.split("-"); // 第一个拆分符号
 for (String s:strings) {
 String[] strings1 = s.split("#"); //# 第二个拆分符号,不是特殊符号,不用 \\

 for (String tmp: strings1){
 System.out.println(tmp);
 }
 }
 }


 public static void main9(String[] args) {
 String str = "192\168円\1円\1円";
 String[] strings = str.split("\\\\");

 for (String s:strings) {
 System.out.println(s);
 }
 }


 // 以空格为分隔标准
 public static void main8(String[] args) {
 String str = "hello world !!!";
 String[] strings = str.split("AA");

 for (String s: strings) {
 System.out.println(s);
 }

 }


 public static void main7(String[] args) {
 String str = "helloworld";
 boolean flg = str.endsWith("world");
 boolean flg2 = str.endsWith("hello");
 System.out.println(flg);
 System.out.println(flg2);
 }

 public static void main6(String[] args) {
 String str = "helloworld";
 boolean flg = str.startsWith("hello",0);
 boolean flg2 = str.startsWith("hello",6);
 System.out.println(flg);
 System.out.println(flg2);
 }


 public static void main5(String[] args) {
 String str = "helloworld";
 boolean flg = str.startsWith("hello");
 boolean flg2 = str.startsWith("world");
 System.out.println(flg);
 System.out.println(flg2);
 }


 public static void main4(String[] args) {
 String str = "helloworld";
 int flg = str.lastIndexOf("world");
 int flg2 = str.lastIndexOf("hi");
 System.out.println(flg);
 System.out.println(flg2);

 int flg3 = str.lastIndexOf("world",9); // 从后向前,指定位置开始查找
 System.out.println(flg3);
 }


 public static void main3(String[] args) {
 String str = "helloworld";
 int flg = str.indexOf("world",3);
 int flg2 = str.indexOf("hi",0);
 System.out.println(flg);
 System.out.println(flg2);
 }

 public static void main2(String[] args) {
 String str = "helloworld";
 int flg = str.indexOf("world");
 int flg2 = str.indexOf("hi");
 System.out.println(flg);
 System.out.println(flg2);
 }




 public static void main1(String[] args) {
 String str = "hello world";
 boolean flg = str.contains("hello");
 System.out.println(flg);
 boolean flg2 = str.contains("Hi");
 System.out.println(flg2);
 }
}