When The Context Starts

To invoke a method when a bean is constructed, use the jakarta.annotation.PostConstruct annotation:

import jakarta.annotation.PostConstruct; (1)
import jakarta.inject.Singleton;
@Singleton
public class V8Engine implements Engine {
    private int cylinders = 8;
    private boolean initialized = false; (2)
    @Override
    public String start() {
        if (!initialized) {
            throw new IllegalStateException("Engine not initialized!");
        }
        return "Starting V8";
    }
    @Override
    public int getCylinders() {
        return cylinders;
    }
    public boolean isInitialized() {
        return initialized;
    }
    @PostConstruct (3)
    public void initialize() {
        initialized = true;
    }
}

import jakarta.annotation.PostConstruct (1)
import jakarta.inject.Singleton
@Singleton
class V8Engine implements Engine {
    int cylinders = 8
    boolean initialized = false (2)
    @Override
    String start() {
        if (!initialized) {
            throw new IllegalStateException("Engine not initialized!")
        }
        return "Starting V8"
    }
    @PostConstruct (3)
    void initialize() {
        initialized = true
    }
}

import jakarta.annotation.PostConstruct
import jakarta.inject.Singleton
@Singleton
class V8Engine : Engine {
    override val cylinders = 8
    var initialized = false
        private set (2)
    override fun start(): String {
        check(initialized) { "Engine not initialized!" }
        return "Starting V8"
    }
    @PostConstruct (3)
    fun initialize() {
        initialized = true
    }
}

To manage when a bean is constructed, see the section on bean scopes.