In Java, class instance variables and static variables have default values: null for all object types, false for boolean primitive and 0 for numeric primitives. But local variables inside a method have no defaults.

Consider the following code snippet:
public static void main(String[] args){
java.util.Date d;
System.out.println(d);
}
It will fail to compile with this error:
variable d might not have been initialized
System.out.println(d);
1 error
However, the following will compile and run successfully:
public static void main(String[] args){
java.util.Date d;
}
Because the rule is that all local variables must be initialized before they are first read. So it's perfectly OK to first declare a local variable without initializing it, initialize it later, and then use it:
public static void main(String[] args){
java.util.Date d;
//do more work
d = new java.util.Date();
System.out.println(d);
}
It may be an old habit from languages like C, where you need to declare all local variables at the beginning of a code block. But in Java with this rule in place, it's best to defer declaring local variables till needed.

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When writing javadocs, IntelliJ automatically adds a closing tag for html elements. For instance, after typing <lt>, it automaticaly adds </lt>, or after typing <p>, it adds </p>. It can be annoying since simple html elements like those used in javadocs don't really need ending tags.
To disable javadoc automatic closing tags in IntelliJ, simply go to IntelliJ Preferences -> Editor -> Smart Keys, then on the right panel, uncheck Automatically insert closing tag.

Intellij 14 screenshot:


 Intellij 15 screenshot:

A related note, JDK 8 has tightened javadoc syntax check, and as a result self-closing elements like <p/>, or <br/> are deemed invalid and will cause failures. See JDK-8020619. However, this checking can be disabled by passing nonstandard option -Xdoclint:none to javadoc tool. For official javadoc guidelines, see How to Write Doc Comments for the Javadoc Tool .
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