There is no need to reinvent the wheel. The Google Guava library provides the Splitter class.

Here's how you can use it along with some test code:

package com.sandbox;

import com.google.common.base.Splitter;
import org.junit.Test;

import java.util.Map;

import static org.junit.Assert.assertEquals;

public class SandboxTest {

    @Test
    public void testQuestionInput() {
        Map<String, String> map = splitToMap("A=4 H=X PO=87");
        assertEquals("4", map.get("A"));
        assertEquals("X", map.get("H"));
        assertEquals("87", map.get("PO"));
    }

    private Map<String, String> splitToMap(String in) {
        return Splitter.on(" ").withKeyValueSeparator("=").split(in);
    }

}

This is one solution. If you want to make it more generic, you can use the StringUtils library.

String value = "{first_name = naresh,last_name = kumar,gender = male}";
value = value.substring(1, value.length()-1);           //remove curly brackets
String[] keyValuePairs = value.split(",");              //split the string to creat key-value pairs
Map<String,String> map = new HashMap<>();               

for(String pair : keyValuePairs)                        //iterate over the pairs
{
    String[] entry = pair.split("=");                   //split the pairs to get key and value 
    map.put(entry[0].trim(), entry[1].trim());          //add them to the hashmap and trim whitespaces
}

For example you can switch

 value = value.substring(1, value.length()-1);

to

 value = StringUtils.substringBetween(value, "{", "}");

if you are using StringUtils which is contained in apache.commons.lang package.

Split the string by , to get individual map entries. Then split them by = to get the key and the value.

Map<String, String> reconstructedUtilMap = Arrays.stream(utilMapString.split(","))
            .map(s -> s.split("="))
            .collect(Collectors.toMap(s -> s[0], s -> s[1]));

Note: As pointed out by Andreas@ in the comments, this is not a reliable way to convert between a map and a string

EDIT: Thanks to Holger for this suggestion.

Use s.split("=", 2) to ensure that the array is never larger than two elements. This will be useful to not lose the contents (when the value has =)

Example: when the input string is "a=1,b=2,c=3=44=5555" you will get {a=1, b=2, c=3=44=5555}

Earlier (just using s.split("=")) will give {a=1, b=2, c=3}

So you can try like this

map<string,string> newMap= new Map<string,string>();
for(String strKey: mapValues.keyset())
{
    newMap.put(strKey, String.valueof(mapValues.get(strKey)));
}

Use Object#toString().

String string = map.toString();

That's after all also what System.out.println(object) does under the hoods. The format for maps is described in AbstractMap#toString().

Returns a string representation of this map. The string representation consists of a list of key-value mappings in the order returned by the map's entrySet view's iterator, enclosed in braces ("{}"). Adjacent mappings are separated by the characters ", " (comma and space). Each key-value mapping is rendered as the key followed by an equals sign ("=") followed by the associated value. Keys and values are converted to strings as by String.valueOf(Object).

That's not possible.

If you can change the string to valid JSON, you can use

import 'dart:convert';
...
Map valueMap = json.decode(value);
// or
Map valueMap = jsonDecode(value);

The string would need to look like

{"first_name" : "fname","last_name" : "lname","gender" : "male", "location" : { "state" : "state", "country" : "country", "place" : "place"} }

You can do the following

1. Removing the { and } characters from the start and end the string. Do not use replace in case there are any occurrences inside it.
2. Split the result into each discrete chunk that forms key-value pairs.
3. Split those into actual key and value
4. The result can readily be convert to a Map because the constructor takes an array where each item is an array with two items and will convert that to a map where the first item is the key, the second the value:

let string = "{executionid=0c3246fb37e65e3368c8c4f30000016ab593bec244daa8df, timeout=10000}";

let keyValuePairs = string.slice(1, -1) //remove first and last character
  .split(/\s*,\s*/)                     //split with optional spaces around the comma
  .map(chunk => chunk.split("="));      //split key=value
  
const map = new Map(keyValuePairs);

console.log(map.get("executionid"));
console.log(map.get("timeout"));

One simple way is to use str_to_map function after you get rid of the double quotes from PersonalInfo column:

val df1 = df.withColumn(
  "PersonalInfo",
  expr("str_to_map(regexp_replace(PersonalInfo, '\"', ''))")
)

df1.show(false)

//+-------+-------+------------------------------------------------------------------------------+
//|Empcode|EmpName|PersonalInfo                                                                  |
//+-------+-------+------------------------------------------------------------------------------+
//|1      |abc    |{email -> abc@gmail.com, Location -> India, Gender -> Male}                   |
//|2      |xyz    |{email -> xyz@gmail.com, Location -> US}                                      |
//|3      |pqr    |{email -> abc@gmail.com, Gender -> Female, Location -> Europe, Mobile -> 1234}|
//+-------+-------+------------------------------------------------------------------------------+