How to Fix \'Failed to Bounce to Type\' Error when Converting Firebase JSON to Java Objects?

"Failed to Bounce to Type" Error When Converting JSON from Firebase to Java Objects

Problem

When attempting to read JSON data from Firebase into Java objects using getValue(User.class), an error occurs:

Exception in thread "FirebaseEventTarget" com.firebase.client.FirebaseException: Failed to bounce to type

Solution

To resolve this error and successfully deserialize JSON into Java objects, follow these steps:

Using Jackson for Serialization and Deserialization

Firebase uses Jackson for serialization and deserialization. Ensure that your Java class matches the JSON structure.

Create a Java Class that Mimics the JSON Structure

Create a Java class with fields that correspond to the properties in the JSON. Use JavaBean properties for automatic mapping.

Handle Partial Loading

If your Java class doesn't include all properties in the JSON, use the @JsonIgnoreProperties annotation to ignore specific properties or set ignoreUnknown = true to ignore all unknown properties.

Handle Partial Saving

When saving Java objects back to Firebase, be aware that Jackson may add properties not present in the original JSON. Use @JsonIgnore annotations on getter methods to prevent this.

Example:

@JsonIgnoreProperties({ "stackId" })
private static class User {
    String handle;
    String name;

    public String getHandle() { return handle; }
    public String getName() { return name; }

    @JsonIgnore
    public String getDisplayName() { return getName() + " (puf)"; }
}

By following these steps, you can successfully deserialize JSON from Firebase into Java objects without encountering the "Failed to Bounce to Type" error.

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