List the interfaces a class implements

This is an example of how to list the interfaces that a class implements in Java. We are using the TreeMap class to get the list of all the interfaces implemented by the class.

  • We get the TreeMap class and use getInterfaces() API method of Class to get its interfaces. It returns a new array of the interfaces implemented by the class or interface represented by this object.
  • We print the fields of the array and we expect to see the NavigableMap, the Cloneable and the Serializable interfaces.

Let’s take a look at the code snippet that follows:

package com.javacodegeeks.snippets.core;

import java.util.TreeMap;

public class ListTheInterfacesAClassImplements {
	public static void main(String[] args) {
		Class<?> clazz = TreeMap.class;
		Class<?>[] interfaces = clazz.getInterfaces();
		System.out.println("TreeMap interfaces:");
		for (int i = 0; i < interfaces.length; i++) {
			System.out.println("t" + interfaces[i]);



TreeMap interfaces:
	interface java.util.NavigableMap
	interface java.lang.Cloneable

This was an example of how to list the interfaces that a class implements in Java.

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Ilias Tsagklis

Ilias is a software developer turned online entrepreneur. He is co-founder and Executive Editor at Java Code Geeks.
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