java-notes-string, Integer,math, regular expressions

Do a few exercises, previously did not how to use the method these times used more.

String String method

1. Interception of str.substring (beginindex,endindex) substring (beginindex)

2.indexOf (), locates the index position of the target Str in the string;

Method of Integer

1.integer.valueof (XXX) convert other types to int type

Regular expressions

1. Determine if the target satisfies the regular expression xxx.matches (regex)

e.g xxx is a digital xxx.matches ("\\d")

Math

1. Take the integer part of the value: Math.floor (XXX), corresponding to a ceil, take the smallest integer greater than or equal to XXX

2. Rounding Math.Round (XXX) for numeric values, there is a problem, the function is to xxx+0.5 after the integer part, in the processing of negative numbers need to be cautious.

java-notes-string, Integer,math, regular expressions