Question

I need a regular expression in java that does the following,

Match a pattern that is NOT the following

• An optional negative sign ( ‘-‘ ) Followed by
• One to four numbers Followed by
• An optional dot character Followed by
• one or many zeroes ( If there is a dot )

 

(?!-{0,1}\\d{1,4}\\.{0,1}0{1,4})

The behavior is below

Expression finds a match for 1
Expression does not find a match for 1.0

when it cones to regex it some times results in a simpler solution if i ask what i need to accomplish as opposed to questions about inner workings.

In my case

I want to catch an decimal number pattern but anything like 1.000 is fine but 1.0001 is not

Some examples

1           No match
1234        No match
99          No Match
1.000000    No match
123.000000  No Match
-123        No Match

1.01        Match
-1.1        Match
12345566    Match 

Answer 1

^-?\d{1,4}(\.0+)?$

You need to use the program itself to reject input. Perhaps match valid numbers, then reject anything that matches this, then return.