?? covariantreturn.java
字號:
//: polymorphism/CovariantReturn.java
class Grain {
public String toString() { return "Grain"; }
}
class Wheat extends Grain {
public String toString() { return "Wheat"; }
}
class Mill {
Grain process() { return new Grain(); }
}
class WheatMill extends Mill {
Wheat process() { return new Wheat(); }
}
public class CovariantReturn {
public static void main(String[] args) {
Mill m = new Mill();
Grain g = m.process();
System.out.println(g);
m = new WheatMill();
g = m.process();
System.out.println(g);
}
} /* Output:
Grain
Wheat
*///:~
?? 快捷鍵說明
復制代碼
Ctrl + C
搜索代碼
Ctrl + F
全屏模式
F11
切換主題
Ctrl + Shift + D
顯示快捷鍵
?
增大字號
Ctrl + =
減小字號
Ctrl + -