Evaluating Flags

`getFlag(key, context)`

Returns the data for a specific flag, or null if the flag does not exist.


var flag = client.getFlag("new-checkout", new FlagEvaluationContext("user-42"));
// FlagData or null

The user id in the context is used to evaluate rollout flags consistently: the same user always gets the same result. When the context or user id is empty, a per-instance anonymous ID is used.

Safe check


if (flag != null && flag.isEnabled()) {
    // Flag is enabled for this user
}

`getFlags(context)`

Returns all flags for the environment as a list.


var flags = client.getFlags(new FlagEvaluationContext("user-42"));
 
for (var flag : flags) {
    System.out.println(flag.getKey() + ": " + flag.isEnabled());
}

Examples by flag type

Boolean flag


var maintenance = client.getFlag("maintenance-mode", context);
 
if (maintenance != null && maintenance.isEnabled()) {
    return maintenancePage();
}

Rollout flag


var newDashboard = client.getFlag("new-dashboard", context);
 
// flag.isEnabled() is true or false based on userId and percentage
if (newDashboard != null && newDashboard.isEnabled()) {
    return newDashboardPage();
}
 
// To see the configured percentage:
if (newDashboard != null && "rollout".equals(newDashboard.getType())) {
    System.out.println(newDashboard.getPercent() + "% of users will see this feature");
}

Before `init()`

If you call getFlag() before init(), the flag will return null (the local cache is still empty).


var client = new CanaryGateClient("cg_key");
// Do not do this:
client.getFlag("feature"); // null
 
// Do this instead:
client.init();
client.getFlag("feature"); // FlagData or null

Flags that do not exist

If the flag does not exist in the environment, getFlag() returns null. Always guard with a null check to avoid breaking the application flow:


// If 'new-feature' does not exist in the environment, enabled will be false
var flag = client.getFlag("new-feature", context);
boolean enabled = flag != null && flag.isEnabled();

getFlag(key, context)