Hamcrest集合操作手册

1. 简介

本文档展示如何使用Hamcrest匹配器处理和测试集合。手册采用示例驱动、注重实践的编写方式——省略不必要的细节和解释。

首先，快速导入后续用到的核心工具类：

import static org.hamcrest.Matchers.*;

2. 操作手册

检查集合是否包含单个元素

List<String> collection = Lists.newArrayList("ab", "cd", "ef");
assertThat(collection, hasItem("cd"));
assertThat(collection, not(hasItem("zz")));

检查集合是否包含多个元素

List<String> collection = Lists.newArrayList("ab", "cd", "ef");
assertThat(collection, hasItems("cd", "ef"));

检查集合所有元素

✅ 严格顺序匹配

List<String> collection = Lists.newArrayList("ab", "cd", "ef");
assertThat(collection, contains("ab", "cd", "ef"));

✅ 任意顺序匹配

List<String> collection = Lists.newArrayList("ab", "cd", "ef");
assertThat(collection, containsInAnyOrder("cd", "ab", "ef"));

检查集合是否为空

List<String> collection = Lists.newArrayList();
assertThat(collection, empty());

检查数组是否为空

String[] array = new String[] { "ab" };
assertThat(array, not(emptyArray()));

检查Map是否为空

Map<String, String> collection = Maps.newHashMap();
assertThat(collection, equalTo(Collections.EMPTY_MAP));

检查Iterable是否为空

Iterable<String> collection = Lists.newArrayList();
assertThat(collection, emptyIterable());

检查集合大小

List<String> collection = Lists.newArrayList("ab", "cd", "ef");
assertThat(collection, hasSize(3));

检查Iterable大小

Iterable<String> collection = Lists.newArrayList("ab", "cd", "ef");
assertThat(collection, Matchers.<String> iterableWithSize(3));

检查所有元素满足条件

List<Integer> collection = Lists.newArrayList(15, 20, 25, 30);
assertThat(collection, everyItem(greaterThan(10)));

3. 总结

本文档是系列技术手册的实验性尝试——继Google Guava集合手册后，现发布Hamcrest集合操作指南。目标是将这些实用技巧在线共享，并在遇到新用例时持续更新。

所有示例代码的完整实现**可在GitHub仓库**获取——基于Maven构建，可直接导入运行。