New to Java

Hi guys,

The one artichle i have read it says wrapper classes are immutable and once you assign a value to a variable(wrapper class type) you wont be able to change that value ,also ;

Integer myInt=new Integer(5);
myInt=10;//i change it no problem showed up.also why it says wrapper classes are immutable?
//how the java works at the background and change it for us what methods does it use to change the value?
//why java made wrapper classes as immutable?

Thanks.