输入: [24, 56, 87, 64, 29, 2, 65]
输出: 87

输入: [45, 3, 65, 32, 64, 12, 43]
输出: 65

// Java Program to find maximum element on HashSet
  
// Importing all java input output classes
// Importing Collection and HashSet class from
// java.util package
import java.io.*;
import java.util.Collections;
import java.util.HashSet;
  
// Class
class GFG {
  
    // Main driver method
    public static void main(String[] args)
    {
  
        // Creating an object of HashSet (of Integer type)
        HashSet<Integer> gfg = new HashSet<Integer>();
  
        // Adding elements in above object of HashSet
        // Custom inputs
        gfg.add(24);
        gfg.add(56);
        gfg.add(87);
        gfg.add(64);
        gfg.add(29);
        gfg.add(2);
        gfg.add(65);
  
        // Print all the elements in the above HashSet
        System.out.println("Elements in HashSet = " + gfg);
  
        // Remember :
        // In computing maximum assign -∞ as initial max
        // In computing minimum assign +∞ as initial min
  
        // Initially assigning -(infinity) as max value
        // so as to deal with garbage value issues.
        int max = Integer.MIN_VALUE;
  
        // For each loop to iterate over elements of HashSet
        // to find maximum among all elements in Set
        for (int var : gfg) {
  
            // For elements in Set
            if (var > max)
  
                // Update the current maximum element
                max = var;
        }
  
        // Display and print the
        // maximum element in a HashSet
        System.out.println("Maximum element in HashSet = "
                           + max);
    }
}

Elements in HashSet = [64, 65, 2, 87, 24, 56, 29]
Maximum element in HashSet = 87

public static <T extends Object & Comparable> T max(Collection coll)

// Java Program to find maximum element on HashSet
  
// Importing all java input-output classes
// Importing Collection and HashSet class from
// java.util package
import java.io.*;
import java.util.Collections;
import java.util.HashSet;
  
// Class
class GFG {
  
    // Main driver method
    public static void main(String[] args)
    {
  
        // Creating object of HashSet
        // Declaring String type objects
        HashSet<String> gfg = new HashSet<String>();
  
        // Adding element in above object of HashSet
        // Custom inputs
        gfg.add("Geekss");
        gfg.add("Geeks");
        gfg.add("Geek");
  
        // Print and display all elements inside the object
        System.out.println("Elements in HashSet = " + gfg);
  
        // Using Collection.max() Method to find
        // max string in HashSet
        Object obj = Collections.max(gfg);
  
        // Display Maximum element in a HashSet
        System.out.println("Maximum element :" + obj);
    }
}

Elements in HashSet = [Geekss, Geek, Geeks]
Maximum element :Geekss