Illustration: Java 23 design patterns Note 1, Java 23 Design Patterns

Illustration: Java 23 design patterns Note 1, Java 23 Design Patterns
Iterator pattern 1.1 Iterator Pattern

The element code in the array arr is displayed in Java as follows:

1 for (int I = 0; I <arr. length; I ++) 2 {3 bytes M. out. println (arr [I]); 4}

Many elements are saved in the array. By specifying the array subscript, we can select any element from it.

In the for statement, I ++ is used to increase the I value by 1 after each loop, so that the next element, the next element, and the next element in the array can be accessed, implements the function of traversing array elements one by one from start to end.

Abstract and generalize the role of the cyclic variable I here to form a pattern that becomes the lterator pattern in the design pattern.

The Iterator mode is used to traverse the set in sequence in the dataset, referred to as the "Iterator" mode.

1.2 sample program

Purpose: place the book in the bookshelf and display the name of the book in sequence.

Aggregate Interface

The Aggregate interface is the interface of the set to be traversed. The class implementing this interface will become a set that can save multiple elements, just like an array. Aggregate indicates clustering.

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Description

Aggregate indicates the set Interface

Iterator interfaces for traversing a set

Book indicates the Book class

BookShelf indicates the class of the BookShelf

BookShelfIterator traverses the class of the bookshelf

Main test program behavior class

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