Java Lang package Introduction Tutorials

Introduction:

java.lang package is the default package which will automatically be available for your class without importing it. Even the members of java.lang package can be accessed directly without using any kind of import statement.

• java.lang package contains many classes, interfaces or Enums.
• Here we have a list of some useful classes or interfaces list which we will cover in further tutorials.

1. java.lang.Object class
2. java.lang.String class
3. java.lang.StringBuffer class
4. java.lang.StringBuilder class
5. java.lang.System class
6. java.lang.Runtime class
7. java.lang.Class class
8. java.lang.Throwable class
9. java.lang.Exception class
10. java.lang.Error class
11. java.lang.RuntimeException class
12. java.lang.Math class
13. java.lang.Thread class
14. java.lang.Runable Interface

• In Java we have eight primitive data types which are byte, short, int, long, float, double, boolean, char; Java provides dedicated class for every primitive data type which is called Wrapper Class.
• All the wrapper classes are also available in java.lang package.

1. java.lang.Byte class [for byte primitive data type]
2. java.lang.Short class [for short primitive data type]
3. java.lang.Integer class [for int primitive data type]
4. java.lang.Long class [for long primitive data type]
5. java.lang.Float class [for float primitive data type]
6. java.lang.Double class [for double primitive data type]
7. java.lang.Boolean class [for boolean primitive data type]
8. java.lang.Character class [for char primitive data type]

Q. Why java.lang package is a default package in Java?

In Java java.lang package has been included in Java by default (there is no need to import) because it contains important classes or APIs- like System class, hashCode() method of Object class, toString() method of Object class etc.- that serve basic purposes like writing a basic Java program.