java.util.HashMap cannot be cast to java.lang.String

This error occurs when you try to cast a HashMap object to a String data type. In Java, casting is a process of converting one data type to another. However, not all data types can be cast to each other.

HashMap is a collection data type in Java that stores data in key-value pairs. It is not a primitive data type like String. Therefore, you cannot cast a HashMap object to a String.

To resolve this error, you need to use the appropriate data type for the object you are trying to cast. If you need to get a String representation of the HashMap, you can use the toString() method of the HashMap class. For example:

HashMap<String, Integer> map = new HashMap<>();
map.put("one", 1);
map.put("two", 2);
String str = map.toString();
System.out.println(str);

This will output: {one=1, two=2}