MySQL kill sleep processes

How to kill sleep/idle/zombie processes in mysql.

MySQL delete table rows and reset index

How to delete all rows of a table and also reset the index.

Insert images into excel with POI

How to insert images when outputting excel using POI packages in Java.

Java common data type and structure operations

Java common data type and structure operations.

Java only creates sub class instance

Code example to show that when a new instance is created, Java only creates instance for the sub class, and for the super class.

Java open url with URL and URLConnection

Java open url with URL and URLConnection.

Java child class also 'inherits' parent class private fields

Code example to show that Java child class also inherits parent class private fields.

Java group list objects by attribute

How to group a list of objects by one of the object’s attribute, which is similar to SQL group by statement and having the same results.

Java base64 encode and decode example

Java base64 encode and decode example.

Java String concatenation performance concern

Java String concatenation performance concern.