reflection

Why should there be reflection?

  1. At runtime, reflection can be used when certain conditions are required to determine which class of objects to use.

  • Strategic mode (flexible)

    abstract BaseStrategy.excute()

    ` `'abstract basestrategy.excute (){// Implement a strategy}Copy the code
    • Strategies: AStrategy, BStrategy, CStrategy

  1. Class personClass = Class.forName("com.data.muse")

    Class personClass1 = Class.forName("com.data.muse")

    PersonClass and personClass1 are the same

  2. How many ways can I get a class object?

    • getClass

    Class class1 = person.getClass()

    • class

    Class class2 = Person.class()

    • class.forName

    Class class3 = Class.forName(com.xxx)

  3. How do I get an object from a class file

    1. For the class

      Class personClass = Class.forName(com.person)

    2. Acquired construction method

      Constructor < Person > Constructor. = personClass getConstructor () / / get the Constructor

      Person Person = constructive.newinstance () // Initializes a Person object

    3. Get the attributes of the Person Class of the Field object through the Class object

      Filed nameFiled = personclass. getFiled ("name") // Get the name attribute of the class

    4. Field is operated to obtain the property value

      String name = String.valueOf(nameFiled.get(person))

What’s BeanUtil for

In practice

1. Individual services and micro-services (vertical segmentation) 2. Hierarchical division of services (horizontal segmentation)Copy the code

  • Reflection allows you to assign an object’s property value to another object

The container

ArrayList: Essentially an array

Add: Capacity expansion: Before adding, check whether the length is sufficient and whether the capacity needs to be expanded

1. The binary of the old length is shifted one bit to the right, equal to 1/2 of the original length, plus the original length 2. If the new length still cannot meet the minimum expansion capacity required, the new length is changed to the minimum expansion capacityCopy the code

Remove: {“a1″,” A2 “,” A3 “,”a4”} For example, delete A2

Size-index -1 4-1-1=2 2. Call the System. arrayCopy (old array, delete element index+1, old array) methodCopy the code

LinkedList

Get a Node

add:

get

The index is in the first half or the second half, and then the for loop iterates until the last one is that value

remove:

All operations on arrays are checked out of boundsCopy the code

Disconnect the front and rear nodes of the node to be deleted