Click here to watch in Youtube :
https://www.youtube.com/watch?v=WYCwpE9NZig&list=UUhwKlOVR041tngjerWxVccw
Country.java
CollectionsSortExample.java
https://www.youtube.com/watch?v=WYCwpE9NZig&list=UUhwKlOVR041tngjerWxVccw
Country.java
public class Country implements Comparable<Object> { private int countryId; private String countryName; public Country(int countryId, String countryName) { super(); this.countryId = countryId; this.countryName = countryName; } public int getCountryId() { return countryId; } public void setCountryId(int countryId) { this.countryId = countryId; } public String getCountryName() { return countryName; } public void setCountryName(String countryName) { this.countryName = countryName; } /* * This method has logic to arrange the Country objects in Ascending order based * on CountryId */ @Override public int compareTo(Object object) { System.out.println("\n"+"compareTo method is called by sort method : "+ object); /* * If this.countryId < country.countryId:then compare method will return * -1 * * If this.countryId > country.countryId:then compare method will return * 1 * * If this.countryId==country.countryId:then compare method will return * 0 */ Country country = (Country) object; return (this.countryId < country.countryId) ? -1 : (this.countryId > country.countryId) ? 1 : 0; } }
import java.util.ArrayList; import java.util.Collections; /* * Example of sort(List<T> list) method */ public class CollectionsSortExample { public static void main(String[] args) { Country india = new Country(1, "India"); Country china = new Country(4, "China"); Country usa = new Country(3, "USA"); Country srilanka = new Country(2, "Srilanka"); ArrayList<Country> countryList = new ArrayList<Country>(); countryList.add(india); countryList.add(china); countryList.add(usa); countryList.add(srilanka); System.out.println("Before Sort : "); for (Country country : countryList) { System.out.println("Country Id: " + country.getCountryId() + " || " + "Country name: " + country.getCountryName()); } /* * Sorts the specified list into ascending order, according to the * natural ordering of its elements. * * All elements in the list must implement the Comparable interface. */ Collections.sort(countryList); System.out.println("\nAfter Sort : "); for (Country country : countryList) { System.out.println("Country Id: " + country.getCountryId() + " || " + "Country name: " + country.getCountryName()); } } }Output
Before Sort : Country Id: 1 || Country name: India Country Id: 4 || Country name: China Country Id: 3 || Country name: USA Country Id: 2 || Country name: Srilanka compareTo method is called by sort method : Country@659e0bfd compareTo method is called by sort method : Country@2a139a55 compareTo method is called by sort method : Country@2a139a55 compareTo method is called by sort method : Country@659e0bfd compareTo method is called by sort method : Country@15db9742 compareTo method is called by sort method : Country@659e0bfd After Sort : Country Id: 1 || Country name: India Country Id: 2 || Country name: Srilanka Country Id: 3 || Country name: USA Country Id: 4 || Country name: China
https://sites.google.com/site/javaee4321/java-collections/CollectionsSortDemoUserDefinedCountryListApp.zip?attredirects=0&d=1
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