Questions and Exercises: Control Flow Statements问题和练习：控制流语句

Questions问题

1. The most basic control flow statement supported by the Java programming language is the ___ statement.Java编程语言支持的最基本的控制流语句是if-then语句。
2. The ___ statement allows for any number of possible execution paths.switch语句允许任意数量的可能执行路径。
3. The ___ statement is similar to the while statement, but evaluates its expression at the ___ of the loop.do-while语句与while语句类似，但在循环的末尾处计算其表达式。
4. How do you write an infinite loop using the for statement?如何使用for语句编写无限循环？for(;;){}
5. How do you write an infinite loop using the while statement?如何使用while语句编写无限循环？

Exercises练习

1. Consider the following code snippet.考虑下面的代码片段。

   if (aNumber >= 0)
       if (aNumber == 0)
           System.out.println("first string");
   else System.out.println("second string");
   System.out.println("third string");

   1. What output do you think the code will produce if aNumber is 3?如果aNumber是3，你认为代码会产生什么输出？
   2. Write a test program containing the previous code snippet; make aNumber 3.编写一个包含前面代码段的测试程序；使aNumber为3。What is the output of the program?程序的输出是什么？Is it what you predicted? Explain why the output is what it is; in other words, what is the control flow for the code snippet?这是你预测的吗？解释为什么输出是这样的；换句话说，代码段的控制流是什么？
   3. Using only spaces and line breaks, reformat the code snippet to make the control flow easier to understand.仅使用空格和换行符，重新格式化代码段以使控制流更易于理解。
   4. Use braces, { and }, to further clarify the code.使用花括号{和}进一步澄清代码。

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