Demo_5.java

import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

class GroupAnagrams{
 public List<List<String>> groupAnagrams(String[] strs) {

 Map<String, List<String>> map = new HashMap<>();
 for(String str: strs){
 char[] arr = str.toCharArray();
 Arrays.sort(arr);
 String sortedStr = String.valueOf(arr);
 // System.out.println(sortedStr);

 if(!map.containsKey(sortedStr)){
 map.put(sortedStr, new ArrayList<>());
 }

 map.get(sortedStr).add(str);
 }
 // System.out.println(map.values());
 return new ArrayList<>(map.values()); 
 }
}
public class Demo_5 {
 public static void main(String[] args) {
 GroupAnagrams ga = new GroupAnagrams();
 List<List<String>> result = ga.groupAnagrams(new String[]{"eat","tea","tan","ate","nat","bat"});

 // Output: [["bat"],["nat","tan"],["ate","eat","tea"]]
 System.out.println(result);
 } 
}