Escape characters (also called escape sequences or escape codes) in general are used to signal an alternative interpretation of a series of characters. In Java, a character preceded by a backslash (\) is an escape sequence and has special meaning to the java compiler. 

Strings are immutable and a new String object is created every time you modify a Sring object. A StringBuffer is a thread-safe, mutable sequence of characters. A StringBuilder is similar to StringBuffer, but with no guarantee of synchronization.

We will discuss String Replace and String Split in Java with some examples. String replace is the process by which we replace parts of a string with another string. Some Java methods directly accept character sequences, while some others accept a regular expression (regex). We will discuss some of these approaces using examples. String split is the process by which a string is split around a delimiter. 

Data with other data types can be converted to String using explicit and automatic ways in Java. Explicit String conversion ways include:

• Use of the toString() method of an object, especially wrapper classes.
• Use of the static overloaded method String.valueOf, passing in the other data type value.
• Use of a String constructor to convert a byte array as a String.

String interning is a method of storing only one copy of each distinct string value, which must be immutable. The distinct values are stored in a string intern pool. The single copy of each string is called its 'intern' and is typically looked up by a method (e.g. String.intern() in Java.).