2-Revision

1，Math.round converts a floating-point number to nearest integer 一样近的时候选大的数 image1

2，Modulus operator % 商的符号由被除数决定 image2

3，自增自减 image3

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4，Mathematical methods in Java image5

5，Converting between Strings and numbers image6

6，String Substrings含头不含尾

7，do while Statement image7