Strings
- String are immutable objects, so when you trying
to change it like: "s.concat("bla")" - you not
changing the current object, you creating the new one
- This statement String s = "dsfsf"
creates new String literal in the run time constant pool and even if the
reference for this literal is lost it still will exist (the most likely)
in memory
- This statement String s = new String
("dsfsf") will create two objects: one on the heap and
second in the run time constant pool there is such String. And the
variable will be reference to the String in the heap
- If call the intern() method it will return the
reference to the same String in the run time constant pool, if
there is no such string there it will create it
- For Strings we can use the += operator
to concatenation and assign in a one line
- Important String methods: charAt(),
concat(), equalsIgnoreCase(), length(), replace(), substring(),
toLowerCase(), toString(), toUpperCase(), trim()
- If you ask charAt() with the index more than
letters in the word-1(indexes starts with 0), you
will get StringIndexOutOfBoundsException
- If you ask substring() with the index more
than letters in the word-1(indexes starts with 0), you won't get an
exception, you will get an empty String
StringBuffer and StringBuilder
- StringBuffer
is StringBuilder
- Important StringBuffer and
StringBuilder methods: append(), delete(), insert(), reverse(),
toString()
- Almost all mentioned methods(except toString) returns
the modified StringBuffer and StringBuilder object, but in comparison
with String this methods change the object on which this methods will be
called
