How to get all values ​​of LinkedHashMap in Java?

LinkedHashMap is a general class of Java Collection Framework, which implements the Map interface. As the name suggests, it is a subclass of the HashMap class and uses a bidirectional LinkedList to store entries in insertion order. It maintains key-value pairs of entries. Key is an object used to get and receive the value associated with it. So we can use this key along with the "get()" method to get all the values ​​from the LinkedHashMap. The purpose of this article is to explain the different ways of printing all the values ​​of a LinkedHashMap.

Java program to get all values ​​of LinkedHashMap

Before jumping directly to the example program, let's first understand a few key points of LinkedHashMap:

LinkedHashMap

As we discussed before, the LinkedHashMap class extends the HashMap class to implement the Map interface. Therefore, it can use all methods of HashMap class and perform similar operations. It stores the mapped elements in the LinkedList in the order of insertion, so whenever we return its elements, it will print them in the order of insertion.

The general syntax of LinkedHashMap is as follows:

Grammar

LinkedHashMap< TypeOfKey, TypeOfValue > nameOfMap = new LinkedHashMap<>();

In the above syntax,

TypeOfKey: Specify the data type of Keys.

TypeOfValue: Specifies the data type of the value to be stored in the map.

nameOfMap: Give your map an appropriate name.

Now, let us create Java program to print all values ​​in LinkedHashMap.

Example 1

The following example demonstrates how to use a for-each loop to get all values ​​from a LinkedHashMap.

method

• First, import the "java.util" package so that we can access Map's functionality.

• Then, create a LinkedHashMap and use the built-in method "put()" to store some elements of the specified type.

• Further, initialize the "index" variable to specify the index.

• Now, make a for-each loop that will iterate over the keys of the LinkedHashMap and increase the index by 1 during each iteration. Also, use the "get()" method to print the value.

import java.util.*;
public class Example1 {
   public static void main(String[] args) {
      // Creating a LinkedHashMap 
      LinkedHashMap<String, Integer> LinkHmap = new LinkedHashMap<>();
      // storing elements to the map
      LinkHmap.put("TShirt", 59);
      LinkHmap.put("Trouser", 60);
      LinkHmap.put("Shirt", 45);
      LinkHmap.put("Watch", 230);
      LinkHmap.put("Shoes", 55);
      // to print all entries
      System.out.println("All items from LinkedHashMap :");
      for (String unKey : LinkHmap.keySet()) {
         System.out.println("Item: " + unKey + ", Quantity: " + LinkHmap.get(unKey));
      }
      // Initializing the index
      int index = 0;
      // iterating using for-each loop
      for (String unKey : LinkHmap.keySet()) {
         // printing the result
         System.out.println("The value at index " + index + " from LinkedHashMap is: " + LinkHmap.get(unKey)); 
         index++; // incrementing the index
      }
   }
}

Output

All items from LinkedHashMap :
Item: TShirt, Quantity: 59
Item: Trouser, Quantity: 60
Item: Shirt, Quantity: 45
Item: Watch, Quantity: 230
Item: Shoes, Quantity: 55
The value at index 0 from LinkedHashMap is: 59
The value at index 1 from LinkedHashMap is: 60
The value at index 2 from LinkedHashMap is: 45
The value at index 3 from LinkedHashMap is: 230
The value at index 4 from LinkedHashMap is: 55

Example 2

In the following example, we will use the iterator interface to get all the values ​​of LinkedHashMap.

method

• Follow the first two steps from the previous example.

• Define an iterator and store the value of LinkedHashMap into it.

• Then, initialize an "index" variable to specify the index.

• Use a while loop to iterate until the end of available values ​​and extract the value. Additionally, the "index" is incremented by 1 during each iteration.

import java.util.*;
public class Example2 {
   public static void main(String[] args) {
      // Creating a LinkedHashMap 
      LinkedHashMap<String, Integer> LinkHmap = new LinkedHashMap<>();
      // storing elements to the map
      LinkHmap.put("TShirt", 59);
      LinkHmap.put("Trouser", 60);
      LinkHmap.put("Shirt", 45);
      LinkHmap.put("Watch", 230);
      LinkHmap.put("Shoes", 55);
      // to print all entries
      System.out.println("All items from LinkedHashMap :");
      for (String unKey : LinkHmap.keySet()) {
         System.out.println("Item: " + unKey + ", Quantity: " + LinkHmap.get(unKey));
      }
      // Defining an iterator
      Iterator<Integer> iter = LinkHmap.values().iterator();
      // Initializing the index
      int index = 0;
      // iterating using while loop
      while (iter.hasNext()) {
         // to get the next value and increment the index
         System.out.println("The value at index " + index + " from LinkedHashMap is: " + iter.next()); 
         index++;
      }
   }
}

Output

All items from LinkedHashMap :
Item: TShirt, Quantity: 59
Item: Trouser, Quantity: 60
Item: Shirt, Quantity: 45
Item: Watch, Quantity: 230
Item: Shoes, Quantity: 55
The value at index 0 from LinkedHashMap is: 59
The value at index 1 from LinkedHashMap is: 60
The value at index 2 from LinkedHashMap is: 45
The value at index 3 from LinkedHashMap is: 230
The value at index 4 from LinkedHashMap is: 55

in conclusion

In this article, we learned about LinkedHashMap and how to create a LinkedHashMap. The purpose of this article is to find different ways to print all the values ​​in a LinkedHashMap. For this operation, we have seen two example programs.

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