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PO
 

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  1. PO
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    <p>If I understood your question correctly it seems you have slightly misunderstood polymorphism, you don't need to know the type that implements the interface. </p> <p>See the following example, there is only one class that directly knows the types of each enemy, the initializing class.</p> <pre><code> import java.util.ArrayList; import java.util.List; public class SO18671999 { public static interface Enemy { public void Attack(Enemy other); public String getName(); } public static class Dragon implements Enemy { String name = "Onyxia"; public void Attack(Enemy other) { System.out.println(this.name + " attacks " + other.getName() + " for 10 dmg!"); } public String getName() { return this.name; } } public static class Cerberus implements Enemy { private String name; private int dmg; public Cerberus(String name, int dmg) { this.name = name; this.dmg = dmg; } @Override public void Attack(Enemy other) { System.out.println(this.name + " attacks " + other.getName() + " for " + this.dmg + " dmg!"); } @Override public String getName() { return this.name; } } public static class EnemyInitializer { private List&lt;Enemy&gt; enemies; public EnemyInitializer() { enemies = new ArrayList&lt;&gt;(); enemies.add(new Dragon()); enemies.add(new Cerberus("CerberusHeadLeft", 10)); enemies.add(new Cerberus("CerberusHeadRight", 10)); enemies.add(new Cerberus("CerberusHeadCenter", 20)); } public List&lt;Enemy&gt; getEnemies() { return enemies; } } public static class EnemyAttacker { private EnemyInitializer eI = new EnemyInitializer(); public void startAttacking() { List&lt;Enemy&gt; enemies = eI.getEnemies(); for (Enemy one : enemies) { for (Enemy two : enemies) { if (one == two) continue; one.Attack(two); } } } } public static void main(String[] args) { EnemyAttacker eAttacker = new EnemyAttacker(); eAttacker.startAttacking(); } } </code></pre>
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    1. POHow can you call a class that is implementing a certain interface without knowing its name?
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    1. USarynaq
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    1. COBut the problems is that I don't have the names of the classes that implements the interface at any given point, so I can't initilize tham like that.
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    2. COSeems like a design problem then, I am sure there are (more advanced than I know of) ways of finding every class that implements an interface at runtime but it is far better for you to use an initializor and maybe read from a textfile or databas.
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