how to handle error message in java

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Java

i have a web application,
when in the form i entered data and submit it,a message is display that you successfully enter the data in the form,that message do not hide after that,if i close it, then all field where i used regular expression appeared and all front end design changed.
i want after successful message it will hide automatically,and form will be ready for next entry, i am new in the field,plz ignore my mistake