Interface TranslationFallbackPolicy

Functional Interface:

This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.

@ThreadSafe
@FunctionalInterface
public interface TranslationFallbackPolicy

Decides whether a failed locale attempt should continue to the next locale candidate.

This policy is intentionally separate from TranslationFailureHandler: fallback policy controls which locale candidates are attempted, while the failure handler controls the final response after fallback stops or all candidates are exhausted.

A failure while evaluating a reachable expression-fragment predicate or interpolating its selected/default fragment is a TranslationFailureReason.RESOLUTION_FAILURE. The safe default fallbackOnMissingTranslationOrNoMatchingAlternative() stops at that failure; fallbackOnAnyFailure() may continue to another locale candidate. Expression-selected generated fragments always have a default translation, so their selection cannot itself produce TranslationFailureReason.NO_MATCHING_ALTERNATIVE.

Implementations may be invoked concurrently and must be thread-safe when shared by a Strings instance.

Since:

3.0.0

Author:

Mark Allen

Method Summary

Modifier and Type	Method	Description
static @NonNull TranslationFallbackPolicy	fallbackOnAnyFailure()	Falls back after every failed locale attempt, including runtime resolution failures.
static @NonNull TranslationFallbackPolicy	fallbackOnMissingTranslationOrNoMatchingAlternative()	Falls back for missing translations and unmatched whole-message alternatives, but stops on resolution failures.
static @NonNull TranslationFallbackPolicy	neverFallback()	Never falls back after a locale attempt fails.
@NonNull Boolean	shouldTryNextLocale(@NonNull TranslationFailureReason reason, @NonNull Locale attemptedLocale, @Nullable Throwable cause)	Determines whether resolution should continue with the next locale candidate.

Method Details

shouldTryNextLocale

@NonNull Boolean shouldTryNextLocale(@NonNull TranslationFailureReason reason,
 @NonNull Locale attemptedLocale,
 @Nullable Throwable cause)

Determines whether resolution should continue with the next locale candidate.

Parameters:

reason - reason the current locale attempt failed, not null

attemptedLocale - locale whose localized strings were attempted, not null

cause - runtime cause for TranslationFailureReason.RESOLUTION_FAILURE, otherwise null

Returns:

whether to try the next candidate, not null

fallbackOnMissingTranslationOrNoMatchingAlternative

static @NonNull TranslationFallbackPolicy fallbackOnMissingTranslationOrNoMatchingAlternative()

Falls back for missing translations and unmatched whole-message alternatives, but stops on resolution failures.

This is the recommended safe default. It stops, for example, when an evaluated expression-fragment predicate is invalid or its selected/default fragment cannot be interpolated.

Returns:

the recommended safe default policy, not null

fallbackOnAnyFailure

static @NonNull TranslationFallbackPolicy fallbackOnAnyFailure()

Falls back after every failed locale attempt, including runtime resolution failures.

This may continue to another locale after an evaluated expression-fragment predicate or selected/default fragment fails. If no later locale resolves, the configured TranslationFailureHandler receives the resolution failure.

This preserves Lokalized 2.x behavior.

Returns:

the permissive fallback policy, not null

neverFallback

static @NonNull TranslationFallbackPolicy neverFallback()

Never falls back after a locale attempt fails.

Returns:

the fail-fast fallback policy, not null