拷贝数组

System.arraycopy(arr1, start, arr2, start, length);

字符，String，int

char 和 string

// char 转 string
Character.toString(c)
String s = String.valueOf(c);
// string 转 char
s.charAt(index)

char 与 int

// char 转 int
char c = '1'
int a = c - '0';
// int 转 char
char c = 40;

int 与 string

// string -> int 
int i = Integer.parseInt(s);
// int -> string
str = Integer.toString(i)
str = String.valueOf(i)

char[] 与 string

char[] s = str.toCharArray();
String s1 = new String(s);

java中表示字符 a ~ z

char c = 'a'

for (int i = 0; i < 26; i++) {
    char dd = (char) (c + i);
    System.out.println(dd);
}

String 相关

反转字符串

String str = new StringBuilder(s).reverse().toString();

字符数组排序