68 lines
1.7 KiB
Java
68 lines
1.7 KiB
Java
// innerclasses/LocalInnerClass.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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// Holds a sequence of Objects
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interface Counter {
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int next();
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}
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public class LocalInnerClass {
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private int count = 0;
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Counter getCounter(final String name) {
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// A local inner class:
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class LocalCounter implements Counter {
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public LocalCounter() {
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// Local inner class can have a constructor
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System.out.println("LocalCounter()");
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}
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@Override
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public int next() {
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System.out.print(name); // Access local final
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return count++;
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}
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}
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return new LocalCounter();
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}
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// Repeat, but with an anonymous inner class:
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Counter getCounter2(final String name) {
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return new Counter() {
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// Anonymous inner class cannot have a named
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// constructor, only an instance initializer:
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{
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System.out.println("Counter()");
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}
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@Override
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public int next() {
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System.out.print(name); // Access local final
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return count++;
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}
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};
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}
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public static void main(String[] args) {
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LocalInnerClass lic = new LocalInnerClass();
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Counter
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c1 = lic.getCounter("Local inner "),
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c2 = lic.getCounter2("Anonymous inner ");
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for(int i = 0; i < 5; i++)
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System.out.println(c1.next());
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for(int i = 0; i < 5; i++)
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System.out.println(c2.next());
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}
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}
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/* Output:
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LocalCounter()
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Counter()
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Local inner 0
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Local inner 1
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Local inner 2
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Local inner 3
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Local inner 4
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Anonymous inner 5
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Anonymous inner 6
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Anonymous inner 7
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Anonymous inner 8
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Anonymous inner 9
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*/
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