Mastering Java Built-In Classes: Methods, Libraries, and Documentation

Java Class Library

A massive set of pre-written code that comes with the Java programming language.

API

Application Programming Interface; a blueprint for how to use pre-built classes and methods.

Libraries

Collections of related classes in Java.

Packages

Organized collections of libraries in Java.

java.lang

A package that can be used without an explicit import statement.

Single-Line Comments

Comments starting with // for short explanations.

Multi-Line Comments

Comments enclosed by /* and */ used for longer explanations or disabling code.

Javadoc Comments

Comments used to generate external HTML documentation.

Immutability

A property of Strings in Java indicating they cannot be changed after creation.

String Literal

A method to create a String by enclosing characters in double quotes.

New Keyword

A method to create a String by using the new operator.

Length Method

Returns the number of characters in a String.

Substring Method

Returns a part of the String based on provided indices.

IndexOf Method

Returns the index of the first occurrence of a substring.

Equals Method

Checks if two Strings have the exact same characters.

CompareTo Method

Compares two Strings lexicographically.

Math Class

A class in Java that provides basic numeric operations.

Static Methods

Methods that can be called on a class without creating an instance.

Math.abs()

Returns the absolute value of a number.

Math.pow()

Returns a base raised to the power of an exponent.

Math.sqrt()

Returns the square root of a number.

Math.random()

Returns a random number between 0.0 (inclusive) and 1.0 (exclusive).

Random Integer Formula

Calculation method to generate random integers within a specified range.

StringIndexOutOfBoundsException

An error thrown when attempting to access an invalid index in a String.

Integer Division

Division where only the integer part of the quotient is kept.

Escape Sequences

Special characters in Strings that have specific functions.

Concatenation

The process of joining two or more Strings together.

Casting

The conversion of one data type to another in programming.