What is the problem?

Question about the task

HashMap of Objects

Java Syntax, Level 8, Lesson 3

Resolved

Displays on the screen correctly. But does not pass the test What is the problem?

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", 5);
        map.put("Tom", 5.5);
        map.put("Arbus", false);
        map.put("Baby", null);
        map.put("Cat", "Cat");
        map.put("Eat", new Long(56));
        map.put("Food", new Character('3'));
        map.put("Gevey", '6');
        map.put("Hugs", 111111111111L);
        map.put("Comp", (double) 123);


       for (HashMap.Entry<String, Object> x: map.entrySet()){
            String key = x.getKey();
            String val = String.valueOf(x);
            System.out.println(key + " - " + val);
        }
    }
}

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", 5); map.put("Tom", 5.5); map.put("Arbus", false); map.put("Baby", null); map.put("Cat", "Cat"); map.put("Eat", new Long(56)); map.put("Food", new Character('3')); map.put("Gevey", '6'); map.put("Hugs", 111111111111L); map.put("Comp", (double) 123); for (HashMap.Entry<String, Object> x: map.entrySet()){ String key = x.getKey(); String val = String.valueOf(x); System.out.println(key + " - " + val); } } }

Comments (6)

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Roy

Level 22 , Bangkok, Thailand

12 June 2019, 10:10

Always test your code before submitting it. You will see you made a mistake in line 28. put the value of x in an Object variable using x.getValue().

Serg

Level 23 , Tyumen, Russian

12 June 2019, 12:23

If you do this:

for (HashMap.Entry<String, Object> x: map.entrySet()){
     String key = x.getKey();
     String val = x.getValue();
     System.out.println(key + " - " + val);
 }

Many mistakes appear.

Roy

Level 22 , Bangkok, Thailand

12 June 2019, 13:28

put the value of x in an Object variable using x.getValue(). Object val = x.getValue();

Serg

Level 23 , Tyumen, Russian

12 June 2019, 14:22

I do not understand what kind of object, because All examples go to the 8th course as

String value = text.getValue();

String value = pair.getValue();

It doesn't work either.

String value = x.getObject();

Roy

Level 22 , Bangkok, Thailand

12 June 2019, 15:42

solution

Yes , it can be a bit confusing at first. It will eventually become clear, when you understand the hierarchy and you understand all objects are instances of the Object class. For now just understand that Java turns all the above values into objects which all belong to the root object class and thus can be referenced using an object variable.

for (HashMap.Entry<String, Object> x: map.entrySet()){
     String key = x.getKey();
     Object val = x.getValue();
     System.out.println(key + " - " + val);
 }

Serg

Level 23 , Tyumen, Russian

12 June 2019, 16:32

Thank you Why is there no such expression on the course? And what is the difference between these expressions? I really want to understand!

Object val = x.getValue();
String val = x.getObject();
String val = x.getValue();