閉包（Closure）是一種能被呼叫的物件，它儲存了建立它的作用域的資訊
public class Programmer {
private String name;
public Programmer() {
super();
}
public Programmer(String name) {
super();
this.name = name;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public void work() {
System.out.println(name + "正在程式設計");
}
}
public interface Teachable {
public void work();
}
public class TeachableProgrammer extends Programmer {
public TeachableProgrammer() {
super();
}
public TeachableProgrammer(String name) {
super(name);
}
// 教學工作任然由TeachableProgrammer定義
private void teach(String content) {
System.out.println(getName() + "正在教授"+content);
}
private class Closure implements Teachable {
String content = "";
Closure (String content){
this.content = content;
}
@Override
public void work() {
// 非靜態內部類實現Teachable的work方法，作用僅僅是向客戶類提供一個回撥外部類的途徑
teach(content);
}
}
// 返回一個非靜態內部類的引用,允許外部類通過該引用來回調外部類的方法
public Teachable getCallbackReference(String content) {
return new Closure(content);
}
}
public class TestClosure {
public static void main(String[] args) {
TeachableProgrammer tp = new TeachableProgrammer("李剛");// 該示例來源於李剛老師的瘋狂講義
// 直接呼叫TeachableProgrammer從Programmer類繼承下來的work方法
tp.work();
// 表明上看是呼叫的Closure的work方法，實際上是通過通過work方法回撥TeachableProgrammer的teach方法
tp.getCallbackReference("數學").work();
}
}