Autocomplete Suggestions Program in Java

Autocomplete suggestion is a common feature in modern applications that helps users predict possible matches as they type. In this Java program, we implement a simple autocomplete system that filters all strings in an array starting with a given prefix and returns them sorted in lexicographical order.

Problem Statement

Write a Java program to implement a basic autocomplete feature. Given an array of strings and a prefix, please find all the strings that start with the given prefix and return them in lexicographical (alphabetical) order.

Example

Input:
String[] words = {“apple”, “application”, “ape”, “banana”, “appetizer”, “apex”};
String prefix = “app”;

Output:
Suggestions: [appetizer, apple, application]

Approach to Solve the Problem

1. Filter Strings: Loop through each string in the array and check if it starts with the given prefix using .startsWith().
2. Store Matches: Add matching words to a list.
3. Sort List: Use Collections.sort() to sort the filtered results.
4. Return or Print: Output the sorted list of suggestions.

Java Program for Autocomplete Suggestions

This Java program implements a basic autocomplete feature by filtering an array of strings to find all elements that start with a given prefix. It uses a loop to check each string with the .startsWith() method, stores matching results in a list, and then sorts the list alphabetically using Collections.sort() before displaying the suggestions.

package com.javacodepoint.stringarray;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

public class AutocompleteSuggestions {

	// Method to get autocomplete suggestions
	public static List<String> getSuggestions(String[] words, String prefix) {
		List<String> suggestions = new ArrayList<>();

		for (String word : words) {
			if (word.startsWith(prefix)) {
				suggestions.add(word);
			}
		}

		// Sort the matching suggestions alphabetically
		Collections.sort(suggestions);

		return suggestions;
	}

	public static void main(String[] args) {
		// Example input
		String[] words = { "apple", "application", "ape", "banana", "appetizer", "apex" };
		String prefix = "app";

		// Get suggestions
		List<String> result = getSuggestions(words, prefix);

		// Print suggestions
		System.out.println("Suggestions: " + result);
	}
}

OUTPUT:
Suggestions: [appetizer, apple, application]

Conclusion

This simple program demonstrates how to build a prefix-based search/autocomplete feature using Java. It combines filtering and sorting to deliver results similar to real-world applications like search bars and code editors.

You can learn the Top 20 string array programs for interview preparation (Click here).