Though Java already has a character type and char keyword to represent and manipulate characters, the language also requires a Character class for two reasons: Character c1 = new Character ('A'); ...

Java gives you the ability to dynamically create strings. Even after you set the string value, you can add more characters to the string value throughout the code. This process lets you build a string ...

- 按照题意, 找到第一个 first index == last index的字母. #### Count appearance with hashmap (more scalable) - 用hashmap存字母的index ...

Java's Scanner class provides a simple and effective way to handle user input. In this simple example, we show how to use Java's Scanner for String input with methods like next (), nextLine () and ...