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ListPerformance.javaAPI DocExample4255Mon Apr 06 18:10:26 BST 1998c08.newcollections

ListPerformance.java

//: ListPerformance.java
//////////////////////////////////////////////////
// Copyright (c) Bruce Eckel, 1998
// Source code file from the book "Thinking in Java"
// All rights reserved EXCEPT as allowed by the
// following statements: You can freely use this file
// for your own work (personal or commercial),
// including modifications and distribution in
// executable form only. Permission is granted to use
// this file in classroom situations, including its
// use in presentation materials, as long as the book
// "Thinking in Java" is cited as the source. 
// Except in classroom situations, you cannot copy
// and distribute this code; instead, the sole
// distribution point is http://www.BruceEckel.com 
// (and official mirror sites) where it is
// freely available. You cannot remove this
// copyright and notice. You cannot distribute
// modified versions of the source code in this
// package. You cannot use this file in printed
// media without the express permission of the
// author. Bruce Eckel makes no representation about
// the suitability of this software for any purpose.
// It is provided "as is" without express or implied
// warranty of any kind, including any implied
// warranty of merchantability, fitness for a
// particular purpose or non-infringement. The entire
// risk as to the quality and performance of the
// software is with you. Bruce Eckel and the
// publisher shall not be liable for any damages
// suffered by you or any third party as a result of
// using or distributing software. In no event will
// Bruce Eckel or the publisher be liable for any
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// indirect, special, consequential, incidental, or
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// possibility of such damages. Should the software
// prove defective, you assume the cost of all
// necessary servicing, repair, or correction. If you
// think you've found an error, please email all
// modified files with clearly commented changes to:
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// address for non-code errors found in the book.)
/////////////////////////////////////////////////

// Demonstrates performance differences in Lists
package c08.newcollections;
import java.util.*;

public class ListPerformance {
  private static final int REPS = 100;
  private abstract static class Tester {
    String name;
    int size; // Test quantity
    Tester(String name, int size) { 
      this.name = name;
      this.size = size;
    }
    abstract void test(List a);
  }
  private static Tester[] tests = {
    new Tester("get", 300) { 
      void test(List a) {
        for(int i = 0; i < REPS; i++) {
          for(int j = 0; j < a.size(); j++)
            a.get(j);
        }
      }
    },
    new Tester("iteration", 300) { 
      void test(List a) {
        for(int i = 0; i < REPS; i++) {
          Iterator it = a.iterator();
          while(it.hasNext())
            it.next();
        }
      }
    },
    new Tester("insert", 1000) { 
      void test(List a) {
        int half = a.size()/2;
        String s = "test";
        ListIterator it = a.listIterator(half);
        for(int i = 0; i < size * 10; i++)
          it.add(s);
      }
    },
    new Tester("remove", 5000) { 
      void test(List a) {
        ListIterator it = a.listIterator(3);
        while(it.hasNext()) {
          it.next();
          it.remove();
        }
      }
    },
  };
  public static void test(List a) {
    // A trick to print out the class name:
    System.out.println("Testing " + 
      a.getClass().getName());
    for(int i = 0; i < tests.length; i++) {
      Collection1.fill(a, tests[i].size);
      System.out.print(tests[i].name);
      long t1 = System.currentTimeMillis();
      tests[i].test(a);
      long t2 = System.currentTimeMillis();
      System.out.println(": " + (t2 - t1));
    }
  }
  public static void main(String[] args) {
    test(new ArrayList());
    test(new LinkedList());
  }
} ///:~