[FIXED] Spring boot: Error when trying to get property values while overriding the spring-context initializer

Issue

console error

2021-07-27 23:09:35.124 ERROR 20275 --- [           main] o.s.boot.SpringApplication               : Application run failed

java.lang.NullPointerException: Cannot invoke "java.lang.Integer.intValue()" because "this.wmPort" is null
        at com.wmock.info.utilities.WireMockInitializer.initialize(WireMockInitializer.java:21) ~[test-classes/:na]

on overriding the initializer

@ActiveProfiles({"test"})
public class WireMockInitializer implements ApplicationContextInitializer<ConfigurableApplicationContext> {

    private WireMockServer wireMockServer;

    @Value("${wiremock.port:2222}")
    private Integer wmPort;

    @Override
    public void initialize(ConfigurableApplicationContext configurableApplicationContext) {
        wireMockServer = new WireMockServer(WireMockConfiguration.wireMockConfig().port(wmPort));
        wireMockServer.start();

        configurableApplicationContext.addApplicationListener(applicationEvent -> {
            if (applicationEvent instanceof ContextClosedEvent) {
                wireMockServer.stop();
            }
        });

        configurableApplicationContext.getBeanFactory()
                .registerSingleton("wireMockServer", wireMockServer);
    }
}

Solution

The issue is because of the initialize method.

package com.wmock.info.utilities;

import lombok.Data;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Configuration;

@Data
@Configuration
@ConfigurationProperties(prefix = "wiremock")
public class CustomConfig {
    private int port;

    public int getPort() {
        return port;
    }
}

public class WireMockInitializer implements ApplicationContextInitializer<ConfigurableApplicationContext> {

    private WireMockServer wireMockServer;

    @Override
    public void initialize(ConfigurableApplicationContext configurableApplicationContext) {

        ConfigurableEnvironment environment = configurableApplicationContext.getEnvironment();
        BindResult<CustomConfig> configProps = Binder.get(environment).bind("wiremock", CustomConfig.class);

        wireMockServer = new WireMockServer(WireMockConfiguration.wireMockConfig().port(configProps.get().getPort()));
        wireMockServer.start();

        configurableApplicationContext.addApplicationListener(applicationEvent -> {
            if (applicationEvent instanceof ContextClosedEvent) {
                wireMockServer.stop();
            }
        });

        configurableApplicationContext.getBeanFactory()
                .registerSingleton("wireMockServer", wireMockServer);
    }
}

Answered By - Prashanth Sams
Answer Checked By - Pedro (JavaFixing Volunteer)