Lesson 09 – MyLibrary Class and ArrayList
- How can we hold books, etc. in a collection?
- MyLibrary object to hold Person & Entry objects
- Introduce ArrayList in scrapbook
- Introduce Java Generics
- Method chaining
使用ArrayList前，要添加java.util.
1 ArrayList<Book> list = new ArrayList<Book>();
2
3 Book b1 = new Book("Great Expectations");
4 Book b2 = new Book("War and Peace");
5 list.add(b1);
6 list.add(b2);
7
8 Person p1 = new Person();
9 p1.setName("Fred");
10 b1.setPerson(p1);
11
12 list.get(0).getPerson().getName();
13
14 list.remmove(b1);
15 list
问题：Inspect提示：
Book cannot be resolved to a type
Book cannot be resolved to a type
Book cannot be resolved to a type
Book cannot be resolved to a type
Book cannot be resolved to a type
Book cannot be resolved to a type
问题解决方法：
1> 在编辑代码时输入new后，按ALT+/ 自动补齐，无反应。
windows / preferences / Java / Editor / Templates / 选new / Edit / 勾选 Automatically insert / 在context里选 Java。
2>Book cannot be resolved to a type，添加Book
1) Click the "Set Import Declarations" button right next to red square "Stop evaluation" button.
2) Select "org.totalbeginner.tutorial* "-> click the "Add Type" button
3) Search for class 'Book' and 'Person' and add them to your MyScrapbook.jpage
小结：
在上面的代码里，用ArrayList列出了Library Class的特性，用Scrapbook验证时，可灵活调用各种方法，比如，根据Book对象去查询：
list.indexOf(b2);
或是由书查读者：
list.get(0).getPerson().getName();