webMethods is used to integrate the applications but, we can do that same by using java also, then why do we use webMethods?

Answer#1

Java is a language. While webMethods is a tool. webMethods provides lots of build-in services as like the API in java.

For using the API, in java again we need to write some codes.

But in webMethods they are providing the drag and drop facilities. So it’s a time consuming process.

Apart from this webMethods supports lot of functionality like publish\subscribe, portal development, brokers etc.

Answer#2

When you can walk, why you need Bike? or if you've bike, do you need car?

Java is a language while webMethods is specialized tool with many built in functions/feature to support guaranteed deliveries, transaction tracking, resubmissions, data transformation, SOA, Event Management, web service, File, EDI, JDBC, SAP, JDE, JMS, MQ Series, integration with multiple applications on multiple platform.

If you'd to do all of that by yourself in Java, you'll look at years to develop full proof solution that webMethods can provide you out of box.

As they say, don't reinvent the wheel.