java - 断言字符串具有一定长度(Java)

Question

有没有办法在方法中断言输入字符串具有一定长度？

我试过 assert stringName[4]; 但似乎不起作用

Answer 1

如果您只想使用 Java 的 assert 关键字而不是任何像 JUnit 这样的库，那么您可以使用:

String myStr = "hello";
assert myStr.length() == 5 : "String length is incorrect";

来自官方文档:

The assertion statement has two forms. The first, simpler form is:

assert Expression1;

where Expression1 is a boolean expression. When the system runs the assertion, it evaluates Expression1 and if it is false throws an AssertionError with no detail message.

The second form of the assertion statement is:

assert Expression1 : Expression2 ;

where: Expression1 is a boolean expression. Expression2 is an expression that has a value. (It cannot be an invocation of a method that is declared void.)

如果您使用的是 JUnit 等测试库，则可以使用以下内容:

String myStr = "hello";
assertEquals(5, myStr.length());

更新:正如 AxelH 在评论中正确指出的那样，编译后，您将第一个解决方案作为 java -ea AssertionTest 运行。 -ea 标志启用断言。