Main.java

public class Main {

    public static void main(String[] args) {
        Box<Integer> box1 = new Box<Integer>(100);
        System.out.println(box1.takeOut());            // 100

        System.out.println(box1.takeOut(
                new IBinaryOp<Integer, Integer>() {
                    public Integer apply(Integer a, Integer b) {
                        return a + b;
                    }
                },
                200));                                 // 300

        System.out.println(box1.takeOut(
                new IBinaryOp<Integer, String>() {
                    public String apply(Integer a, String b) {
                        return a + b;
                    }
                },
                "円"));                                 // 100円

        Box<String> box2 = new Box<String>("百");
        System.out.println(box2.takeOut());              // 百

        System.out.println(box2.takeOut(
                new IBinaryOp<String, String>() {
                    public String apply(String a, String b) {
                        return a + b;
                    }
                },
                "円"));                                  // 百円
    }
}