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Using the Java SDK

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Providing User Data​

Many calls to the AppFlags client require passing an AppFlagsUser, which is needed to evaluate Targeting Rules for Feature Flags.

The AppFlagsUser object contains a key, which is a unique identifier for the user.

AppFlagsUser user = AppFlagsUser.builder()
    .key("USER_KEY")
    .build();

If you are not evaluating feature flags for a particular user, you can pass the SYSTEM user instead:

AppFlagsUser user = AppFlagsUser.SYSTEM;

Getting the value for a Feature Flag​

To retrieve the active value for a particular Feature Flag, use the relevant getVariation function.

For example for a boolean flag:

boolean booleanValue = appFlagsClient.getBooleanVariation("flag_key", user, false);

Default values​

The third parameter is a default value. This value will be returned if the flag does not exist or if the AppFlags client is unable to connect to the AppFlags servers. You can set the default value to null if you choose. For example:

// boolean default
boolean booleanValue = appFlagsClient.getBooleanVariation("flag_key", user, false);

// null default
Boolean booleanOrNull = appFlagsClient.getBooleanVariation("flag_key", user, null);

Each variation type​

There are getVariation functions for boolean, number, and string Feature Flags:

boolean booleanFlag = appFlagsClient.getBooleanVariation("boolean_flag", user, false);

double numberFlag = appFlagsClient.getNumberVariation("number_flag", user, 0.0);

String stringFlag = appFlagsClient.getStringVariation("string_flag", user, "defaultValue");

Get Notified When Feature Flags Update​

The AppFlags client will automatically update whenever your Feature Flags change.

To get notified when Feature Flags update, your application can be notified with a ConfigurationChangedHandler:

appFlagsClient.addConfigurationChangedHandler(() -> {
    // Feature flags have been updated
});

Example Repository​

For a full example of using AppFlags in a Java application, see https://github.com/AppFlags/example-java.