package 实验;

abstract class Bred {
    String name;

    public void speakName() {
        System.out.println("这是一只 " + this.name);
    }

    public void math() {
    };

    public String toString() {
        return name;
    }
}

class FengHuang extends Bred {
    final String name = "凤凰";

    public void math() {
        System.out.println("他会做算术");
    }
}

class Psittaciformes extends Bred {
    final String name = "鹦鹉";

    public void math() {
        System.out.println("他会做算术");
    }
}

class MaQue extends Bred {
    final String name = "麻雀";

    public void math() {
        System.out.println("他不会做算术");
    }
}

class Work {

    public static Bred getAdd(String name) throws Exception {
        Bred aa = null;
        try {
            if ("凤凰".equals(name)) {
                aa = new FengHuang();
            }
            if ("鹦鹉".equals(name)) {
                aa = new Psittaciformes();
            }
            if ("麻雀".equals(name)) {
                aa = new MaQue();
            }
        } catch (Exception e) {
            System.out.println(e);
        }
        return aa;
    }
}

public class WorkGround {
    public static void main(String[] args) {
        // Bred a=null;
        try {
            Work w = new Work();
            w.getAdd("凤凰").speakName();
        } catch (Exception e) {
            System.out.println(e);
        }
    }
}
结果是 这是一只 null
我希望是  这是一只凤凰


[ 本帖最后由 long8863 于 2013-3-5 19:30 编辑 ]