寫程式應該要盡可能的避免duplicate code(重複程式碼)，一樣的、沒有價值的東西，一直寫幹嘛？對吧！
在Android開發上，不管你是使用哪一種Architecture(MVC、MVP、MVVM...等等)，都一定有Model層，Model是我們在程式開發上最原始、最簡單的東西。
但打開你的Project看看你的Model，會發現重複的method一直在出現【getter、setter、equals、hashCode、toString....】等等等。
現在，我們透過【AutoValue】就可以大幅的簡化它了。
這個由google maintain的github開源項目，在本文章撰寫時最新版本是v1.4.1
Library projects:
Gradle:
//auto-value provided 'com.google.auto.value:auto-value:1.4.1' annotationProcessor 'com.google.auto.value:auto-value:1.4.1'
以下使用一個Book類別做示範
Before:
public class Book {
private String name;
private int price;
private String author;
public Book(String name, int price, String author) {
this.name = name;
this.price = price;
this.author = author;
}
@Override
public String toString() {
return "Book{"
+ "name=" + name
+ ", price=" + price
+ ", author=" + author
+ "}";
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getPrice() {
return price;
}
public void setPrice(int price) {
this.price = price;
}
public String getAuthor() {
return author;
}
public void setAuthor(String author) {
this.author = author;
}
}
Book book = new Book("安森瓦舍", 87, "Anson");
System.out.println("書名：" + book.getName());
System.out.println("價格：" + book.getPrice());
System.out.println("作者：" + book.getAuthor());
After:
@AutoValue
public abstract class Book {
public abstract String name();
public abstract int price();
public abstract String author();
public static Book create(String name, int price, String author) {
return new AutoValue_Book(name, price, author);
}
}
Book book = Book.create("安森瓦舍", 87, "Anson");
System.out.println("書名：" + book.name());
System.out.println("價格：" + book.price());
System.out.println("作者：" + book.author());
如果你想使用Builder pattern的話
@AutoValue
public abstract class Book {
public abstract String name();
public abstract int price();
public abstract String author();
public static Book create(String name, int price, String author) {
return builder()
.name(name)
.price(price)
.author(author)
.build();
}
public static Builder builder() {
return new AutoValue_Book.Builder();
}
@AutoValue.Builder
public abstract static class Builder {
public abstract Builder name(String name);
public abstract Builder price(int price);
public abstract Builder author(String author);
public abstract Book build();
}
}
Book book = Book.create("安森瓦舍", 87, "Anson");
System.out.println("書名：" + book.name());
System.out.println("價格：" + book.price());
System.out.println("作者：" + book.author());
延伸閱讀：
● 最簡潔的Model層 - AutoValue 使用介紹【二】
● 最簡潔的Model層 - AutoValue 使用介紹【三】
