Java Platform, Enterprise Edition (Java EE) 8 The Java EE Tutorial

## Injecting Objects by Using Producer Methods

Producer methods provide a way to inject objects that are not beans, objects whose values may vary at runtime, and objects that require custom initialization. For example, if you want to initialize a numeric value defined by a qualifier named `@MaxNumber`, then you can define the value in a managed bean and then define a producer method, `getMaxNumber`, for it:

    private int maxNumber = 100;
    ...
    @Produces @MaxNumber int getMaxNumber() {
        return maxNumber;
    }

When you inject the object in another managed bean, the container automatically invokes the producer method, initializing the value to 100:

    @Inject @MaxNumber private int maxNumber;

If the value can vary at runtime, then the process is slightly different. For example, the following code defines a producer method that generates a random number defined by a qualifier called `@Random`:

    private java.util.Random random =
        new java.util.Random( System.currentTimeMillis() );

    java.util.Random getRandom() {
            return random;
    }

    @Produces @Random int next() {
        return getRandom().nextInt(maxNumber);
    }

When you inject this object in another managed bean, you declare a contextual instance of the object:

    @Inject @Random Instance<Integer> randomInt;

You then call the `get` method of the `Instance`:

    this.number = randomInt.get();

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