如何在JAVA控制台输出时判断是否为四位整数

Answer 1

用正则表达式判断啊，网上一大堆

Answer 2

用try-catch-finally

Answer 3

可以使用求余运算符：a%1==0 来判断值是否为整数，返回为boolean值。然后使用Integer的toString().length() 来判断长度。

Answer 4

可以转换成字符串，然后判断字符个数。在判断第一位是否为零

Answer 5

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Answer 6

00 0 0

Answer 7

大于999小于10000不就行了么