String and Array

1. ASCII字符 string.charAt(i) 返回的事int值
String last = "Kennedy";
int key = last.charAt(2);
System.out.println(key);
==>
110 返回ASCII码数值

2. 若果想返回int数值

str1="2345";
int x=str1.charAt(2)-'0';
==> x=4;

3. string.trim() 除去string前后的空格

4. StringBuilder
4.1 append()可以使char和int
4.2 toString()