Chengmai NIIT 3 days before Android training review Java Basics

It belongs to the leak check.

Java source files are compiled to generate a class file/bytecode file to help you achieve a truly cross-platform. A class is compiled into a class file. The execution is then interpreted through the JVM (the Java Virtual machine).

Java of 8 a basic data type :

Four integer types: Byte (1 bytes different and range different 2^7~2^7), short (2), int (4), Long (8)

Two floating-point types: Float (4), double (8)

Boolean type: Boolean (1)

Character type: char (2)

Java Specification

* Multiple classes can be defined in a Java file, but only one class is exposed and must be the same as the public class name

* If there is more than one class in a file, how to define the file name: if the non-public class, the file name randomly

Public, publicly, class members are completely public, stating that any class can access the member

Protected, protected, other classes in the same package can be accessed, and only subclasses in different packages can access

Default, the other class in the same package is accessible to the member, and the no-access specifier is the default

Private, privately owned, that class is private, and can only be accessed by that class

Interface ( Interface ) :

The variables in the interface are all static final

The methods in the interface are all public abstract

Chengmai NIIT 3 days before Android training review Java Basics