Null pointer exception

Question about the task

HashMap of Objects

Java Syntax, Level 8, Lesson 3

Under discussion

I'm confused as to how to work around the null pointer exception with this object.

map.put("Baby", null);
map.put("Hugs", 111111111111L);   <--------- This is also not correct, right???

Here is the code to get the value. Does toString() not work on null objects?

String value = person.getValue().toString();

I also tried to change the things put in the HashMap but it won't let you do that. Very confused.

There is a HashMap<String, Object>. 10 different object pairs have been added to it.
Display the contents of the collection, each element on a new line.

Example output: (here we just show one line):
Sim - 5

Requirements:

The program must create a HashMap variable with (String, Object) elements. The variable must be initialized immediately.
The program should not read values from the keyboard.
The program should add 10 different objects to the collection in accordance with the conditions.
The program should display the contents of the collection on the screen, each pair on a new line.

package com.codegym.task.task08.task0806; import java.util.HashMap; import java.util.Map; /* HashMap of Objects */ public class Solution { public static void main(String[] args) throws Exception { HashMap<String, Object> map = new HashMap<String, Object>(); map.put("Sim", new Integer(5)); map.put("Tom", new Double(5.5)); map.put("Arbus", new Boolean(false)); map.put("Baby", new String("Zach")); map.put("Cat", "Cat"); map.put("Eat", new Long(56)); map.put("Food", new Character('3')); map.put("Gevey", new Character('6')); map.put("Hugs", new String("111111111111L")); map.put("Comp", new Double(123)); //write your code here for (Map.Entry<String, Object> person : map.entrySet()) { String key = person.getKey(); String value = person.getValue().toString(); System.out.println(key + " - " + value); } } }

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Soonho

Level 14 , Seoul, Korea, Republic of

18 February 2021, 14:17

That is NOT object instance. That is primitive data type, So it can't use that function "getValue()".

Gellert Varga

Level 23 , Szekesfehervar, Hungary

7 February 2021, 21:58

You don't need this codeline: String value = person.getValue().toString(); Yes, this doesn't work: null.toString(); Such a method doesn't exist what works on a null. 111111111111111L is not a mistake, this is the sign of a Long value. P.s: Just get the keys and the values inside the println command!