Holds a sequence of Objects : Inner Class « Class « Java






Holds a sequence of Objects

  
// : c08:LocalInnerClass.java
// Holds a sequence of Objects.
// From 'Thinking in Java, 3rd ed.' (c) Bruce Eckel 2002
// www.BruceEckel.com. See copyright notice in CopyRight.txt.

interface Counter {
  int next();
}

public class LocalInnerClass {

  private int count = 0;

  Counter getCounter(final String name) {
    // A local inner class:
    class LocalCounter implements Counter {
      public LocalCounter() {
        // Local inner class can have a constructor
        System.out.println("LocalCounter()");
      }

      public int next() {
        System.out.print(name); // Access local final
        return count++;
      }
    }
    return new LocalCounter();
  }

  // The same thing with an anonymous inner class:
  Counter getCounter2(final String name) {
    return new Counter() {
      // Anonymous inner class cannot have a named
      // constructor, only an instance initializer:
      {
        System.out.println("Counter()");
      }

      public int next() {
        System.out.print(name); // Access local final
        return count++;
      }
    };
  }

  public static void main(String[] args) {
    LocalInnerClass lic = new LocalInnerClass();
    Counter c1 = lic.getCounter("Local inner "), c2 = lic
        .getCounter2("Anonymous inner ");
    for (int i = 0; i < 5; i++)
      System.out.println(c1.next());
    for (int i = 0; i < 5; i++)
      System.out.println(c2.next());
  }
} ///:~



           
         
    
  








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