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package micro.benchmarks;

import java.util.ArrayList;

import org.openjdk.jmh.annotations.Benchmark;
import org.openjdk.jmh.annotations.Level;
import org.openjdk.jmh.annotations.Scope;
import org.openjdk.jmh.annotations.Setup;
import org.openjdk.jmh.annotations.State;
import org.openjdk.jmh.annotations.Warmup;

Benchmarks cost of ArrayList.
/** * Benchmarks cost of ArrayList. */
public class ArrayListBenchmark extends BenchmarkBase { private static final int N = 100; @State(Scope.Benchmark) public static class ThreadState { final ArrayList<Integer> list = new ArrayList<>(N); } @Benchmark @Warmup(iterations = 20) public void addBoxedAndClear(ThreadState state) { for (int i = 0; i < N; ++i) { state.list.add(i); } state.list.clear(); } @Benchmark @Warmup(iterations = 20) public void addNullAndClear(ThreadState state) { for (int i = 0; i < N; ++i) { state.list.add(null); } state.list.clear(); } @State(Scope.Benchmark) public static class ClearedThreadState { final ArrayList<Integer> list = new ArrayList<>(N); // We don't want to measure the cost of list clearing @Setup(Level.Invocation) public void beforeInvocation() { list.clear(); } } @Benchmark @Warmup(iterations = 20) public void addNull(ClearedThreadState state) { for (int i = 0; i < N; ++i) { state.list.add(null); } } }