(Learning memo) Java Level 2 measures: Question range

Self-learning notes TBE

Question range

operator

Operators are symbols used in arithmetic and mathematics, such as + (plus),-(minus), = (equal), etc.

① Bit operator (&, ^, |, ~)
② Shift operator (<<, >>, >>>)

Shift each bit of the value of interest to the right or left

③ Assignment operator (& =, ^ =, | =, << =, >> =, >>> =)

Operators used when assigning numbers and letters to variables

④ instance of operator

An operator for dynamically determining the type of an object -Is the object an instance of a class? -Is the object an instance of a child class of a class? · Is the object an instance that implements a particular interface?

⑤ Diamond operator For example List a = new ArrayList (); List a = new ArrayList<>(); Can be abbreviated as

Control statement

Added in Java 8 Writing a program in a lambda expression reduces the amount of code and makes it easier to read.

Classes and inheritance

Class modifier (default), public, final, abstract What is inheritance? Extends Type conversion (cast) this and super Interface implements

Variables and methods

Variable and method modifiers (default), public, protected, private, final, static

What is an override

Redefining a method defined in a parent class in a child class Overrides occur in two or more classes that have an inheritance relationship

What is overload?

Defining methods with the same name in the same class The name is the same, but the number of arguments, the type of arguments, and the order are different.

Generic name

Up to Java SE 6: "generic name" Java SE 7 or later: "Generics"

Collection class

--"List", "Set" and "Map" are prepared as interfaces. --When actually using it, use a class that implements these interfaces. ・ ArrayList of List is often used ・ List ・ ・ ・ Interface ・ ArrayList ・ ・ ・ ・ It is a class that implements List. -A class that implements the interface of the collection framework like ArrayList is called a collection class.

package

Package and classpath Classpath Package definition package Use of package import

Exception handling

Exception definition Exception handling try-catch? Finally throw throws

thread

What is a thread? Creating a thread

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