60 lines
1.1 KiB
Java
60 lines
1.1 KiB
Java
// staticchecking/drc/DogAndRobotCollections.java
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// (c)2016 MindView LLC: see Copyright.txt
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// We make no guarantees that this code is fit for any purpose.
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// Visit http://mindviewinc.com/Books/OnJava/ for more book information.
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package staticchecking.drc;
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import java.util.*;
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class Dog {
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public void talk() {
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System.out.println("Woof!");
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}
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public void reproduce() { }
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}
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class Robot {
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public void talk() {
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System.out.println("Click!");
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}
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public void oilChange() { }
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}
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public class DogAndRobotCollections {
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public static void main(String[] args) {
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List<Dog> dogList = new ArrayList<>();
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List<Robot> robotList = new ArrayList<>();
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for(int i = 0; i < 10; i++)
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dogList.add(new Dog());
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// dogList.add(new Robot()); // Compile-time error
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for(int i = 0; i < 10; i++)
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robotList.add(new Robot());
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// robotList.add(new Dog()); // Compile-time error
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// No cast necessary
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dogList.forEach(Dog::talk);
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// No cast necessary
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robotList.forEach(Robot::talk);
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}
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}
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/* Output:
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Woof!
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Woof!
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Woof!
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Woof!
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Woof!
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Woof!
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Woof!
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Woof!
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Woof!
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Woof!
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Click!
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Click!
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Click!
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Click!
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Click!
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Click!
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Click!
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Click!
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Click!
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Click!
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*/
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