91  * before and after a single date. By contrast, the Japanese calendar system

    91  * before and after a single date. By contrast, the Japanese calendar system

    92  * has one era for the reign of each Emperor.

    92  * has one era for the reign of each Emperor.

    93  * <p>

    93  * <p>

    94  * Instances of {@code Era} may be compared using the {@code ==} operator.

    94  * Instances of {@code Era} may be compared using the {@code ==} operator.

    95  *

    95  *

    97  * This interface must be implemented with care to ensure other classes operate correctly.

    97  * This interface must be implemented with care to ensure other classes operate correctly.

    98  * All implementations must be singletons - final, immutable and thread-safe.

    98  * All implementations must be singletons - final, immutable and thread-safe.

    99  * It is recommended to use an enum whenever possible.

    99  * It is recommended to use an enum whenever possible.

   100  *

   100  *

   101  * @since 1.8

   101  * @since 1.8