How do I insert values into a Map K V

Question

I am trying to create a map of strings to strings  Below is what I ve tried but neither method works  What s wrong with it   public class Data       private final Map lt String  String gt  data   new HashMap lt  gt         data  John      Taxi Driver       data put  John    Taxi Driver

User · Answer

The two errors you have in your code are very different.

The first problem is that you're initializing and populating your Map in the body of the class without a statement. You can either have a static Map and a static {//TODO manipulate Map} statement in the body of the class, or initialize and populate the Map in a method or in the class' constructor.

The second problem is that you cannot treat a Map syntactically like an array, so the statement data["John"] = "Taxi Driver"; should be replaced by data.put("John", "Taxi Driver"). If you already have a "John" key in your HashMap, its value will be replaced with "Taxi Driver".

User · Answer

Try this code  HashMap lt String  String gt  map   new HashMap lt String  String gt     map put  EmpID   EmpID   map put  UnChecked    1

User · Answer

There are two issues here   Firstly  you can t use the    syntax like you may be able to in other languages  Square brackets only apply to arrays in Java  and so can only be used with integer indexes   data put is correct but that is a statement and so must exist in a method block  Only field declarations can exist at the class level  Here is an example where everything is within the local scope of a method   public class Data        public static void main String   args             Map lt String  String gt  data   new HashMap lt String  String gt              data put  John    Taxi Driver             data put  Mark    Professional Killer                If you want to initialize a map as a static field of a class then you can use Map of  since Java 9   public class Data       private static final Map lt String  String gt  DATA   Map of  John    Taxi Driver        Before Java 9  you can use a static initializer block to accomplish the same thing   public class Data       private static final Map lt String  String gt  DATA   new HashMap lt  gt          static           DATA put  John    Taxi Driver

User · Answer

The syntax is   data put  John   Taxi driver

[java] How do I insert values into a Map<K, V>?

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