Gson 错误：java.lang.IllegalArgumentException：类 android.app.ExitTransitionCoordinator 声明了多个名为 mHandler 的 JSON 字段

Question

我正在尝试转换名为MyData 的自定义对象的List：

class MyData {
    private String id;
    private String title;
    private Drawable AppIcon;

    public MyData() {}

    public MyData(String id, String title, Drawable _AppIcon) {
        this.id = id;
        this.title = title;
        this.AppIcon = _AppIcon;
    }


    public String getId() {
        return id;
    }

    public String getTitle() {
        return title;
    }

    public Drawable getAppIcon() {
        return this.AppIcon;
    }

}

我正在尝试按照我在Gson 文档中阅读的内容进行转换：

Type listType = new TypeToken<List<MyData>>(){}.getType();
List<MyData> appsList = new ArrayList<>();
String ArrayStr = new Gson().toJson(appsList, listType);

然后抛出一个Exception，这里是logcat的输出：

java.lang.IllegalArgumentException: class android.app.ExitTransitionCoordinator declares multiple JSON fields named mHandler
        at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.getBoundFields(ReflectiveTypeAdapterFactory.java:170)
        at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.create(ReflectiveTypeAdapterFactory.java:100)
        at com.google.gson.Gson.getAdapter(Gson.java:423)
        at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.createBoundField(ReflectiveTypeAdapterFactory.java:115)
        at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.getBoundFields(ReflectiveTypeAdapterFactory.java:164)
        at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.create(ReflectiveTypeAdapterFactory.java:100)
        at com.google.gson.Gson.getAdapter(Gson.java:423)
        at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.createBoundField(ReflectiveTypeAdapterFactory.java:115)
        at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.getBoundFields(ReflectiveTypeAdapterFactory.java:164)
        at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.create(ReflectiveTypeAdapterFactory.java:100)
        at com.google.gson.Gson.getAdapter(Gson.java:423)
        at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.createBoundField(ReflectiveTypeAdapterFactory.java:115)
        at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.getBoundFields(ReflectiveTypeAdapterFactory.java:164)
        at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.create(ReflectiveTypeAdapterFactory.java:100)
        at com.google.gson.Gson.getAdapter(Gson.java:423)
        at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.createBoundField(ReflectiveTypeAdapterFactory.java:115)
        at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.getBoundFields(ReflectiveTypeAdapterFactory.java:164)
        at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.create(ReflectiveTypeAdapterFactory.java:100)
        at com.google.gson.Gson.getAdapter(Gson.java:423)
        at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.createBoundField(ReflectiveTypeAdapterFactory.java:115)
        at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.getBoundFields(ReflectiveTypeAdapterFactory.java:164)
        at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.create(ReflectiveTypeAdapterFactory.java:100)
        at com.google.gson.Gson.getAdapter(Gson.java:423)
        at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.createBoundField(ReflectiveTypeAdapterFactory.java:115)
        at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.getBoundFields(ReflectiveTypeAdapterFactory.java:164)
        at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.create(ReflectiveTypeAdapterFactory.java:100)
        at com.google.gson.Gson.getAdapter(Gson.java:423)
        at com.google.gson.internal.bind.ArrayTypeAdapter$1.create(ArrayTypeAdapter.java:48)
        at com.google.gson.Gson.getAdapter(Gson.java:423)
        at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.createBoundField(ReflectiveTypeAdapterFactory.java:115)
        at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.getBoundFields(ReflectiveTypeAdapterFactory.java:164)
        at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.create(ReflectiveTypeAdapterFactory.java:100)
        at com.google.gson.Gson.getAdapter(Gson.java:423)
        at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.createBoundField(ReflectiveTypeAdapterFactory.java:115)
        at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.getBoundFields(ReflectiveTypeAdapterFactory.java:164)
        at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.create(ReflectiveTypeAdapterFactory.java:100)
        at com.google.gson.Gson.getAdapter(Gson.java:423)
        at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.createBoundField(ReflectiveTypeAdapterFactory.java:115)
        at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.getBoundFields(ReflectiveTypeAdapterFactory.java:164)
        at com.google.gson.internal.bind.ReflectiveType

我在 google 中查找了几个小时，但没有找到对我有帮助的答案，我没有在我的代码中做任何特别的事情，只是从官方文档中复制了这些行并将其替换为我的对象。

Answer 1

Gson 将Drawable 视为普通的POJO 类并遍历所有getters 并尝试将它们序列化。看起来Drawable 与其他一些对象创建了循环。不要存储整个对象，而是尝试通过在构造函数中复制它们来仅序列化所需的字段：

public MyData(String id, String title, Drawable appIcon) {
    this.id = id;
    this.title = title;
    this.minWidth = appIcon.getMinimumWidth();
    this.direction = appIcon.getLayoutDirection();
    // copy other fields
}

或为Drawable 类编写自定义序列化程序：

• Gson Advanced — Custom Serialization for Simplification (Part 1)
• GSON - Custom serializer in specific case