Java Can'；t实例化抽象类'；基本信用卡'；

我在这里遇到了一个棘手的问题，我试图创建层次结构可分组类，但我遇到了一个奇怪的错误：

java.lang.InstantiationException: Can't instantiate abstract class br.com.dinda.models.credit_cards.base.CreditCard
    at java.lang.reflect.Constructor.newInstance()(Constructor.java:-2)
    at com.google.gson.internal.ConstructorConstructor$3.construct()(ConstructorConstructor.java:104)
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read()(ReflectiveTypeAdapterFactory.java:186)
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.read()(ReflectiveTypeAdapterFactory.java:103)
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read()(ReflectiveTypeAdapterFactory.java:196)
    at com.google.gson.Gson.fromJson()(Gson.java:810)
    at com.google.gson.Gson.fromJson()(Gson.java:775)
    at com.google.gson.Gson.fromJson()(Gson.java:724)
    at com.google.gson.Gson.fromJson()(Gson.java:696)
    at com.newrelic.agent.android.instrumentation.GsonInstrumentation.fromJson()(GsonInstrumentation.java:90)
    at br.com.dinda.models.CheckoutData.fromJson()(CheckoutData.java:38)
    at br.com.dinda.repositories.CheckoutRepository.getPersistedCheckout()(CheckoutRepository.java:46)
    at br.com.dinda.repositories.CheckoutRepository.getCheckout()(CheckoutRepository.java:28)
    at br.com.dinda.presenters.CheckoutStep2Presenter.onCreate()(CheckoutStep2Presenter.java:43)
    at br.com.dinda.views.fragments.CheckoutStep2Fragment.onCreateView()(CheckoutStep2Fragment.java:183)
    at android.support.v4.app.Fragment.performCreateView()(Fragment.java:1789)
    at android.support.v4.app.FragmentManagerImpl.moveToState()(FragmentManager.java:955)
    at android.support.v4.app.FragmentManagerImpl.moveToState()(FragmentManager.java:1138)
    at android.support.v4.app.FragmentManagerImpl.moveToState()(FragmentManager.java:1120)
    at android.support.v4.app.FragmentManagerImpl.dispatchActivityCreated()(FragmentManager.java:1929)
    at android.support.v4.app.FragmentActivity.onStart()(FragmentActivity.java:547)
    at android.support.v7.app.AppCompatActivity.onStart()(AppCompatActivity.java:-1)
    at br.com.dinda.views.activities.BaseActivity.onStart()(BaseActivity.java:49)
    at android.app.Instrumentation.callActivityOnStart()(Instrumentation.java:1238)
    at android.app.Activity.performStart()(Activity.java:6288)
    at android.app.ActivityThread.performLaunchActivity()(ActivityThread.java:2397)
    at android.app.ActivityThread.handleLaunchActivity()(ActivityThread.java:2494)
    at android.app.ActivityThread.access$900()(ActivityThread.java:157)
    at android.app.ActivityThread$H.handleMessage()(ActivityThread.java:1356)
    at android.os.Handler.dispatchMessage()(Handler.java:102)
    at android.os.Looper.loop()(Looper.java:148)
    at android.app.ActivityThread.main()(ActivityThread.java:5530)
    at java.lang.reflect.Method.invoke()(Method.java:-2)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run()(ZygoteInit.java:733)
    at com.android.internal.os.ZygoteInit.main()(ZygoteInit.java:623)

我的代码是：

@Parcel(converter = CreditCard.CreditCardConverter.class)
public abstract class CreditCard {

    public static final String CREDIT_CARD_MASK = "**** **** **** ####";
    public static ImmutableList<CreditCard> CREDIT_CARD_OPERATORS;

    static {
        CREDIT_CARD_OPERATORS = ImmutableList.of(
                new EloCreditCard(),
                new VisaCreditCard(),
                new MastercardCreditCard(),
                new HipercardCreditCard()
        );
    }

    @SerializedName("credit_card_id")
    Integer id;

    @SerializedName("credit_card_name")
    String name;

    @SerializedName("credit_card_number")
    String number;

    @SerializedName("credit_card_month")
    Integer month;

    @SerializedName("credit_card_year")
    Integer year;

    @SerializedName("credit_card_operator")
    String operator;

    String securityCode;

    boolean saveCreditCard;

    /**
     * Funcao para retornar o nome da operadora do cartao
     * eg. visa ou mastercard
     * @return nome da operadora
     */
    @NonNull
    public abstract String getCreditCardOperatorName();

    /**
     * Funcao que retorna o regex para verificar a validade da operadora do cartao (nums sao validos para a bandeira especificada)
     * eg. visa = Pattern.compile("^4[0-9]{15}$"),
     * @return @Pattern para a operadora especificada
     */
    public abstract Pattern creditCardRegex();

    /**
     * Funcao que retorna o Regex parcial para identificar a operadora do cartao
     * * eg. visa = Pattern.compile("^4[0-9]*$")
     * @return @Pattern para a verificacao parcial da operadora do cartao
     */
    public abstract Pattern partialCreditCardRegex();

    /**
     * Funcao que retorna o logo da bandeira da operadaora do cartao quando o msm esta selecionado
     * @return Drawable do logo
     */
    @DrawableRes
    public abstract int operatorLogoRes();

    /**
     * Funcao que retorna o logo da bandeira da operadaora do cartao quando o msm <b>nao</b> esta selecionado
     * @return Drawable do logo desmarcado (cinza)
     */
    @DrawableRes
    public abstract int operatorLogoDisabledRes();

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (!(o instanceof CreditCard)) return false;

        CreditCard card = (CreditCard) o;

        return getCreditCardOperatorName().equals(card.getCreditCardOperatorName());

    }

    @Override
    public int hashCode() {
        return getCreditCardOperatorName().hashCode();
    }

    public static class CreditCardConverter implements ParcelConverter<CreditCard> {

        @Override
        public void toParcel(CreditCard input, android.os.Parcel parcel) {
            parcel.writeParcelable(Parcels.wrap(input), 0);
        }

        @Override
        public CreditCard fromParcel(android.os.Parcel parcel) {
            return Parcels.unwrap(parcel.readParcelable(CreditCard.class.getClassLoader()));
        }
    }
}

我注意到了将它们注释为@Parcel，但我似乎不知道发生了什么

此问题发生在Parceler的1.1.5版上

---

谢谢。

我相信您遇到了这个问题：

多态性

请注意，Parceler不会展开继承层次结构，因此 多态字段将作为基类的实例展开。 这是因为包裹商选择性能而不是检查 .getClass（）用于每个数据段

参考海关 序列化部分，了解使用多态性的示例 田地

因此，您应该能够使用自定义序列化来解决这个问题

---

实际上我忘了在序列化程序中添加CustomTypeAdapter

if (json != null) {
            Gson gson = new Gson();
            return gson.fromJson(json, CheckoutData.class);

应该是：

if (json != null) {
            Gson gson = new GsonBuilder().registerTypeAdapter(CreditCard.class, new CreditCardTypeAdapter()).create();
            return gson.fromJson(json, CheckoutData.class);

---

抱歉打扰了，希望它能帮助其他人

一般来说，您不能实例化抽象类，也不能实例化接口。您必须扩展abstract类。这就是问题所在，我没有实例化抽象类，我不明白为什么Parceler调用基类，而不是它的子类。提供的堆栈跟踪似乎指向Gson在实例化抽象类时遇到问题。在Github上回答：我明白了，但这并不能解决我的问题。我还在想到底发生了什么。

if (json != null) {
            Gson gson = new Gson();
            return gson.fromJson(json, CheckoutData.class);

if (json != null) {
            Gson gson = new GsonBuilder().registerTypeAdapter(CreditCard.class, new CreditCardTypeAdapter()).create();
            return gson.fromJson(json, CheckoutData.class);