Questions and Exercises: Characters and Strings问题和练习：字符和字符串

Questions

1. What is the initial capacity of the following string builder?以下字符串生成器的初始容量是多少？

   StringBuilder sb = new StringBuilder("Able was I ere I saw Elba.");

2. Consider the following string:考虑以下字符串：

   String hannah = "Did Hannah see bees? Hannah did.";

   1. What is the value displayed by the expression hannah.length()?表达式hannah.length()显示的值是多少？

   2. What is the value returned by the method call hannah.charAt(12)?方法调用hannah.charAt(12)返回的值是多少？

   3. Write an expression that refers to the letter b in the string referred to by hannah.写一个表达式，引用hannah引用的字符串中的字母b。

3. How long is the string returned by the following expression?以下表达式返回的字符串有多长？What is the string?绳子是什么？

   "Was it a car or a cat I saw?".substring(9, 12)

4. In the following program, called ComputeResult, what is the value of result after each numbered line executes?在以下名为ComputeResult的程序中，执行每个编号行后的result值是多少？

   public class ComputeResult {
       public static void main(String[] args) {
           String original = "software";
           StringBuilder result = new StringBuilder("hi");
           int index = original.indexOf('a');
   
   /*1*/   result.setCharAt(0, original.charAt(0));
   /*2*/   result.setCharAt(1, original.charAt(original.length()-1));
   /*3*/   result.insert(1, original.charAt(4));
   /*4*/   result.append(original.substring(1,4));
   /*5*/   result.insert(3, (original.substring(index, index+2) + " ")); 
   
           System.out.println(result);
       }
   }

Exercises练习

1. Show two ways to concatenate the following two strings together to get the string "Hi, mom.":显示将以下两个字符串连接在一起以获得字符串"Hi, mom."的两种方法：

   String hi = "Hi, ";
   String mom = "mom.";

2. Write a program that computes your initials from your full name and displays them.编写一个程序，根据您的全名计算您的姓名首字母并显示它们。

3. An anagram is a word or a phrase made by transposing the letters of another word or phrase; for example, "parliament" is an anagram of "partial men," and "software" is an anagram of "swear oft".字谜是将另一个单词或短语的字母转置而成的单词或短语；例如，“parliament”是一个“partial men”的字谜，“software”是一个“swear oft”的字谜。Write a program that figures out whether one string is an anagram of another string.编写一个程序，计算一个字符串是否是另一个字符串的字谜。The program should ignore white space and punctuation.程序应该忽略空格和标点符号。

Check your answers.检查你的答案。