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Does a HashSet have keys?

HashSet stores only objects no such key value pairs maintained.

tutorialspoint.com - Difference between HashMap and HashSet in Java. - Tutorialspoint

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HashMap and HashSet both are one of the most important classes of Java Collection framework.

Following are the important differences between HashMap and HashSet.

Sr. No. Key HashMap HashSet 1 Implementation Hashmap is the implementation of Map interface. Hashset on other hand is the implementation of set interface. 2 Internal implementation Hashmap internally do not implements hashset or any set for its implementation. Hashset internally uses Hashmap for its implementation. 3 Storage of elements HashMap Stores elements in form of key-value pair i.e each element has its corresponding key which is required for its retrieval during iteration. HashSet stores only objects no such key value pairs maintained. 4 Method to add element Put method of hash map is used to add element in hashmap. On other hand add method of hashset is used to add element in hashset. 5 Index performance Hashmap due to its unique key is faster in retrieval of element during its iteration. HashSet is completely based on object so compared to hashmap is slower. 6 Null Allowed Single null key and any number of null value can be inserted in hashmap without any restriction. On other hand Hashset allows only one null value in its collection,after which no null value is allowed to be added.

Example of Hashmap vs Hashset

JavaTester.java

Live Demo

import java.util.HashSet; public class JavaTester { public static void main(String[] args){ HashSet hs = new HashSet(); hs.add("John"); hs.add("Smith"); hs.add("Peter"); System.out.println("Before adding duplicate values

" + hs); hs.add("John"); hs.add("Smith"); System.out.println("

After adding duplicate values

" + hs); hs.add(null); hs.add(null); System.out.println("

After adding null values

" + hs); } }

Output

Before adding duplicate values [John, Smith, Peter] After adding duplicate values [John, Smith, Peter] After adding null values [null, John, Smith, Peter]

Example

JavaTester.java

Live Demo

import java.util.HashMap; public class JavaTester { public static void main(String[] args){ HashMap hm = new HashMap(); hm.put(12, "John"); hm.put(2, "Smith"); hm.put(7, "Peter"); System.out.println("

HashMap object output :

" + hm); hm.put(12, "Smith"); System.out.println("

After inserting duplicate key :

" + hm); } }

Output

HashMap object output : {2=Smith, 7=Peter, 12=John} After inserting duplicate key : {2=Smith, 7=Peter, 12=John}

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What are the characteristics of shifting?

The characteristics of Shifting cultivation are field rotation, the absence of fertilisation and draught animals, the use of only human labour, the use of a stick or hoe, and brief rotation periods with extended fallow periods.

byjusexamprep.com - What are the characteristics of shifting cultivation? - BYJU'S Exam Prep

Characteristics of Shifting Cultivation

In this farming system, farmers only grow food for their own families. In nearby markets, some minor surpluses are traded, bartered (commodity for commodity exchange), or sold for cash. As a result, the migrant population is economically independent and self-sufficient, and the resulting economy has little potential for rapid growth.

The characteristics of shifting cultivation are as follows:

Field rotation

Fire is used to cleanse the earth.

The land is left fallow for several years to allow regeneration.

The seeds are sown in the ashes after the first monsoon rains, usually harvested from September to October.

Human labor as the primary input

Draft animals are not used.

Sorting Cultivation:

Sorting requires clearing the jungle.

However, cutting down trees and clearing bushes accelerates soil erosion and accentuates rainfall variability, leading to drought or flooding.

Problems and Prospects:

The overall impact is decreased soil fertility.

Ecosystems are losing their resilience characteristics.

A population dependent on cultivation faces food shortages, fuelwood, and fodder.

As a result, the nutritional standard decreases.

Summary:

What are the characteristics of shifting cultivation?

Field rotation rather than crop rotation, the absence of fertilization and draught animals, the employment of only human labor, the use of a stick or hoe, and short rotation periods with lengthy fallow periods have been defined as the major characteristics of shifting farming.

Does a HashSet have keys?

Can I learn piano on Android?

What is a piano exercise called?

Following are the important differences between HashMap and HashSet.

Example of Hashmap vs Hashset

JavaTester.java

Live Demo

" + hs); hs.add("John"); hs.add("Smith"); System.out.println("

After adding duplicate values

" + hs); hs.add(null); hs.add(null); System.out.println("

After adding null values

" + hs); } }

Output

Example

JavaTester.java

Live Demo

HashMap object output :

" + hm); hm.put(12, "Smith"); System.out.println("

After inserting duplicate key :

" + hm); } }

Output

Which is easier to learn violin or piano?

What does F2 do?

What are the characteristics of shifting?

Characteristics of Shifting Cultivation

The characteristics of shifting cultivation are as follows:

Field rotation

Fire is used to cleanse the earth.

The land is left fallow for several years to allow regeneration.

Human labor as the primary input

Draft animals are not used.

Sorting Cultivation:

Sorting requires clearing the jungle.

Problems and Prospects:

The overall impact is decreased soil fertility.

Ecosystems are losing their resilience characteristics.

A population dependent on cultivation faces food shortages, fuelwood, and fodder.

As a result, the nutritional standard decreases.

Summary:

What are the characteristics of shifting cultivation?

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