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Java ServiceLoader toString() Method
Description
The java ServiceLoader toString() method returns a string describing this service.
Declaration
Following is the declaration for java.util.ServiceLoader.toString() method
public String toString()
Parameters
NA
Return Value
This method returns a descriptive string
Exception
NA
Getting String representation of ServiceLoader Instance Example
In order the service to be registered, we need a META-INF/services folder in our classpath. In this particular folder, we need a text file with the name of the interface we implementing containing a single line listing the concrete class name of the implementation. In our case the name of the file is com.tutorialspoint.ServiceProvider and contains this line −
com.tutorialspoint.ServiceImplementation
Our service code is the following −
package com.tutorialspoint; public class ServiceImplementation extends ServiceProvider { public String getMessage() { return "Hello World"; } }
The following code loads the service that is registered and uses it to get the message from the service. We've created a method getDefault() which returns a ServiceProvider. This method gets a serviceLoader object using ServiceLoader.load(). Using serviceLoader.toString() method, we've printed the string representation of the service loader. Then serviceLoader is iterated and first provider is returned. In the end we're throwing error if provider is not returned. Then using getDefault() we've retrieved the serviceProvider and printed the message using this object.
package com.tutorialspoint; import java.util.ServiceLoader; public abstract class ServiceProvider { public static ServiceProvider getDefault() { // load our plugin ServiceLoader<ServiceProvider> serviceLoader = ServiceLoader.load(ServiceProvider.class); // print the serviceLoader as a string System.out.println(serviceLoader.toString()); // checking if load was successful for (ServiceProvider provider : serviceLoader) { return provider; } throw new Error("Something is wrong with registering the addon"); } public abstract String getMessage(); public static void main(String[] ignored) { // create a new provider and call getMessage() ServiceProvider provider = ServiceProvider.getDefault(); System.out.println(provider.getMessage()); } }
Output
Let us compile and run the above program, this will produce the following result −
java.util.ServiceLoader[com.tutorialspoint.ServiceProvider] Hello World
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