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BAEL-1331: Quick Example: Comparator vs Comparable in Java Source code and Unit Tests added.

This commit is contained in:
gschambial 2017-11-13 21:01:06 +05:30
parent 3319b28b9c
commit 40ceddea2b
9 changed files with 265 additions and 0 deletions
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51
core-java/src/main/java/com/baeldung/comparable/Player.java Normal file
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package com.baeldung.comparable;
public class Player implements Comparable<Player> {
private int ranking;
private String name;
private int age;
public Player(int ranking, String name, int age) {
this.ranking = ranking;
this.name = name;
this.age = age;
}
public int getRanking() {
return ranking;
}
public void setRanking(int ranking) {
this.ranking = ranking;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
@Override
public String toString() {
return this.name;
}
@Override
public int compareTo(Player otherPlayer) {
return (this.getRanking() - otherPlayer.getRanking());
}
}

24
core-java/src/main/java/com/baeldung/comparable/PlayerSorter.java Normal file
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package com.baeldung.comparable;
import java.util.ArrayList;
import java.util.Collections;
public class PlayerSorter {
public static void main(String[] args) {
ArrayList<Player> footballTeam = new ArrayList<Player>();
Player player1 = new Player(59, "John", 20);
Player player2 = new Player(67, "Roger", 22);
Player player3 = new Player(45, "Steven", 24);
footballTeam.add(player1);
footballTeam.add(player2);
footballTeam.add(player3);
System.out.println("Before Sorting : " + footballTeam);
Collections.sort(footballTeam);
System.out.println("After Sorting : " + footballTeam);
}
}

46
core-java/src/main/java/com/baeldung/comparator/Player.java Normal file
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package com.baeldung.comparator;
public class Player {
private int ranking;
private String name;
private int age;
public Player(int ranking, String name, int age) {
this.ranking = ranking;
this.name = name;
this.age = age;
}
public int getRanking() {
return ranking;
}
public void setRanking(int ranking) {
this.ranking = ranking;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
@Override
public String toString() {
return this.name;
}
}

12
core-java/src/main/java/com/baeldung/comparator/PlayerAgeComparator.java Normal file
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package com.baeldung.comparator;
import java.util.Comparator;
public class PlayerAgeComparator implements Comparator<Player> {
@Override
public int compare(Player firstPlayer, Player secondPlayer) {
return (firstPlayer.getAge() - secondPlayer.getAge());
}
}

26
core-java/src/main/java/com/baeldung/comparator/PlayerAgeSorter.java Normal file
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package com.baeldung.comparator;
import java.util.ArrayList;
import java.util.Collections;
public class PlayerAgeSorter {
public static void main(String[] args) {
ArrayList<Player> footballTeam = new ArrayList<Player>();
Player player1 = new Player(59, "John", 22);
Player player2 = new Player(67, "Roger", 20);
Player player3 = new Player(45, "Steven", 24);
footballTeam.add(player1);
footballTeam.add(player2);
footballTeam.add(player3);
System.out.println("Before Sorting : " + footballTeam);
//Instance of PlayerAgeComparator
PlayerAgeComparator playerComparator = new PlayerAgeComparator();
Collections.sort(footballTeam, playerComparator);
System.out.println("After Sorting by age : " + footballTeam);
}
}

12
core-java/src/main/java/com/baeldung/comparator/PlayerRankingComparator.java Normal file
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package com.baeldung.comparator;
import java.util.Comparator;
public class PlayerRankingComparator implements Comparator<Player> {
@Override
public int compare(Player firstPlayer, Player secondPlayer) {
return (firstPlayer.getRanking() - secondPlayer.getRanking());
}
}

26
core-java/src/main/java/com/baeldung/comparator/PlayerRankingSorter.java Normal file
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package com.baeldung.comparator;
import java.util.ArrayList;
import java.util.Collections;
public class PlayerRankingSorter {
public static void main(String[] args) {
ArrayList<Player> footballTeam = new ArrayList<Player>();
Player player1 = new Player(59, "John", 22);
Player player2 = new Player(67, "Roger", 20);
Player player3 = new Player(45, "Steven", 40);
footballTeam.add(player1);
footballTeam.add(player2);
footballTeam.add(player3);
System.out.println("Before Sorting : " + footballTeam);
//Instance of PlayerRankingComparator
PlayerRankingComparator playerComparator = new PlayerRankingComparator();
Collections.sort(footballTeam, playerComparator);
System.out.println("After Sorting by ranking : " + footballTeam);
}
}

26
core-java/src/test/java/com/baeldung/comparable/ComparableUnitTest.java Normal file
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package com.baeldung.comparable;
import static org.junit.Assert.assertEquals;
import java.util.ArrayList;
import java.util.Collections;
import org.junit.Test;
public class ComparableUnitTest {
@Test
public void whenUsingComparable_thenSortedList() {
ArrayList<Player> footballTeam = new ArrayList<Player>();
Player player1 = new Player(59, "John", 20);
Player player2 = new Player(67, "Roger", 22);
Player player3 = new Player(45, "Steven", 24);
footballTeam.add(player1);
footballTeam.add(player2);
footballTeam.add(player3);
Collections.sort(footballTeam);
assertEquals(footballTeam.get(0).getName(), "Steven");
assertEquals(footballTeam.get(2).getRanking(), 67);
}
}

42
core-java/src/test/java/com/baeldung/comparator/ComparatorUnitTest.java Normal file
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package com.baeldung.comparator;
import static org.junit.Assert.assertEquals;
import java.util.ArrayList;
import java.util.Collections;
import org.junit.Test;
public class ComparatorUnitTest {
@Test
public void whenUsingRankingComparator_thenSortedList() {
ArrayList<Player> footballTeam = new ArrayList<Player>();
Player player1 = new Player(59, "John", 20);
Player player2 = new Player(67, "Roger", 22);
Player player3 = new Player(45, "Steven", 24);
footballTeam.add(player1);
footballTeam.add(player2);
footballTeam.add(player3);
PlayerRankingComparator playerComparator = new PlayerRankingComparator();
Collections.sort(footballTeam, playerComparator);
assertEquals(footballTeam.get(0).getName(), "Steven");
assertEquals(footballTeam.get(2).getRanking(), 67);
}
@Test
public void whenUsingAgeComparator_thenSortedList() {
ArrayList<Player> footballTeam = new ArrayList<Player>();
Player player1 = new Player(59, "John", 20);
Player player2 = new Player(67, "Roger", 22);
Player player3 = new Player(45, "Steven", 24);
footballTeam.add(player1);
footballTeam.add(player2);
footballTeam.add(player3);
PlayerAgeComparator playerComparator = new PlayerAgeComparator();
Collections.sort(footballTeam, playerComparator);
assertEquals(footballTeam.get(0).getName(), "John");
assertEquals(footballTeam.get(2).getRanking(), 45);
}
}