MyBenchmark.java

package org.typeunsafe;

import org.openjdk.jmh.annotations.*;

import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
import java.util.concurrent.TimeUnit;

@State(Scope.Thread)
@BenchmarkMode(Mode.Throughput)
@OutputTimeUnit(TimeUnit.MILLISECONDS)
public class MyBenchmark {

  private int index = 0;
  private Object[] listObjects;
  private Object[] mixedObjects;

  @Setup
  public void prepare() {

    listObjects = new Object[]{
        new ArrayList<Object>() {
          {
            add(1);
            add(2);
            add(3);
          }
        },
        new LinkedList<Object>() {
          {
            add("Plop");
            add("Da Plop");
          }
        },
        new ArrayList<Object>(),
        new LinkedList<Object>() {
          {
            add("Plop");
          }
        },
        new ArrayList<Object>() {
          {
            add(100);
            add(200);
            add(300);
          }
        },
    };

    mixedObjects = new Object[]{
        new ArrayList<Object>() {
          {
            add(1);
            add(2);
            add(3);
          }
        },
        new LinkedList<Object>() {
          {
            add("Plop");
            add("Da Plop");
          }
        },
        new ArrayList<Object>(),
        "That's a string",
        69
    };
  }

  private int nextIndex() {
    return (index + 1) % listObjects.length;
  }

  @Benchmark
  public int if_only_lists() {
    Object obj = listObjects[nextIndex()];
    if (obj instanceof List) {
      return ((List) obj).size();
    }
    return -1;
  }

  @Benchmark
  public int if_mixed_objects() {
    Object obj = mixedObjects[nextIndex()];
    if (obj instanceof List) {
      return ((List) obj).size();
    }
    return -1;
  }

  @Benchmark
  public int trycatch_only_lists() {
    try {
      return ((List) listObjects[nextIndex()]).size();
    } catch (ClassCastException e) {
      return -1;
    }
  }

  @Benchmark
  public int trycatch_mixed_objects() {
    try {
      return ((List) mixedObjects[nextIndex()]).size();
    } catch (ClassCastException e) {
      return -1;
    }
  }
}

results.txt

Benchmark                            Mode  Cnt       Score      Error   Units
MyBenchmark.if_mixed_objects        thrpt   20  111741.999 ± 1463.380  ops/ms
MyBenchmark.if_only_lists           thrpt   20  114264.985 ± 2083.101  ops/ms
MyBenchmark.trycatch_mixed_objects  thrpt   20  113566.186 ± 1157.158  ops/ms
MyBenchmark.trycatch_only_lists     thrpt   20  118021.702 ± 1691.867  ops/ms

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