import com.google.common.base.CharMatcher; import com.google.common.base.Charsets; import com.google.common.base.Function; import com.google.common.base.Joiner; import com.google.common.base.Preconditions; import com.google.common.base.Splitter; import com.google.common.collect.ArrayListMultimap; import com.google.common.collect.ImmutableList; import com.google.common.collect.ImmutableMap; import com.google.common.collect.ImmutableSet; import com.google.common.collect.Lists; import com.google.common.collect.MapDifference; import com.google.common.collect.Maps; import com.google.common.collect.Multimap; import com.google.common.collect.Multimaps; import com.google.common.collect.Ordering; import com.google.common.collect.Sets; import com.google.common.collect.Sets.SetView; import com.google.common.io.Files; import com.google.common.primitives.Doubles; import com.google.common.primitives.Ints; import static com.google.common.base.Predicates.* ; import static com.google.common.collect.Iterables.* ; public class Test { private String title; private Date date; private String author; public static void main(String[] args) { // 普通Collection的创建 List<String> list = Lists.newArrayList(); Set <String> set = Sets.newHashSet(); Map <String, String> map = Maps.newHashMap(); // 不变Collection的创建 ImmutableList<String> iList = ImmutableList.of("a", "b", "c" ); ImmutableSet <String> iSet = ImmutableSet.of("e1", "e2" ); ImmutableMap <String, String> iMap = ImmutableMap.of("k1", "v1", "k2", "v2" ); // 文件读取演示 File file = new File("/home/alexis/tests/text1" ); List <String> content = null ; try { content = Files.readLines(file, Charsets.UTF_8); } catch (IOException ex) { ex.printStackTrace(); for (String line : content) { System.out.println(line); // 基本类型操作 int [] arr = {1, 2, 3 }; int [] arr2 = {1, 2, 3 }; int intCmp = Ints.compare(1, 2 ); int doubleCmp = Doubles.compare(1.1, 1.2 ); int index = Ints.indexOf(arr, 1 ); boolean contains = Ints.contains(arr, 1 ); int max = Ints.max(arr); int min = Ints.min(arr); int [] arr3 = Ints.concat(arr, arr2); // List转数组 List<Integer> intList = Lists.newArrayList(1, 2, 3 ); int [] intArr = Ints.toArray(intList); // 便利字符匹配类 CharMatcher // 判断匹配结果 boolean result = CharMatcher.inRange('a', 'z').or(CharMatcher.inRange('A', 'Z')).matches('K' ); // 保留数字文本 String s1 = CharMatcher.DIGIT.retainFrom("abc 123 efg" ); // 删除数字文本 String s2 = CharMatcher.DIGIT.removeFrom("abc 123 efg" ); // 更多方法参见 http://docs.guava-libraries.googlecode.com/git/javadoc/com/google/common/base/CharMatcher.html // Joiner 与 Splitter // 使用 "/" 串联字符串 String[] subdirs = { "usr", "local", "lib" }; String path = Joiner.on("/" ).join(subdirs); System.out.println(path); // 使用 "," 切分字符串并去除空串与空格 String s = "dog ,,, cat,fish," ; Iterable <String> i = Splitter.on(',' ).omitEmptyStrings().trimResults().split(s); for (String ss : i) { System.out.println(ss); // 集合过滤器 // 使用自定义回调方法对Map的每个Value进行操作 ImmutableMap<String, Double> m = ImmutableMap.of("a", 1.1, "b", 1.2 ); // Function<F, T> F表示apply()方法input的类型，T表示apply()方法返回类型 Map<String, Double> m2 = Maps.transformValues(m, new Function<Double, Double> () { double e = 1.2 ; @Override public Double apply(Double input) { return input * e; System.out.println(m2); // 条件过滤集合 // 方法来自 com.google.common.collect.Iterables 以及 com.google.common.base.Predicates ImmutableList<String> names = ImmutableList.of("Aleksander", "Jaran", "Integrasco", "Guava", "Java" ); Iterable <String> fitered = filter(names, or(equalTo("Aleksander"), equalTo("Jaran" ))); System.out.println(fitered); // 对计划排序，并生成排序后的集合拷贝视图 Man man1 = new Man("Alexis", "Drazen" ); Man man2 = new Man("Bob", "Lee" ); Man man3 = new Man("Vince", "Carter" ); ImmutableList <Man> men = ImmutableList.of(man1, man2, man3); Comparator <Man> byLastName = new Comparator<Man> () { public int compare( final Man p1, final Man p2) { return p1.getLastName().compareTo(p2.getLastName()); Comparator <Man> byFirstName = new Comparator<Man> () { public int compare( final Man p1, final Man p2) { return p1.getFirstName().compareTo(p2.getFirstName()); // 先按 lastName 再按 firstName 排序，最后倒序 List<Man> sortedCopy = Ordering.from(byLastName).compound(byFirstName).reverse().sortedCopy(men); System.out.println(sortedCopy); // 集合的合集，交集，差集 HashSet<Integer> setA = Sets.newHashSet(1, 2, 3, 4, 5 ); HashSet <Integer> setB = Sets.newHashSet(4, 5, 6, 7, 8 ); SetView <Integer> union = Sets.union(setA, setB); System.out.println( "union:" ); for (Integer integer : union) System.out.println(integer); SetView <Integer> difference = Sets.difference(setA, setB); System.out.println( "difference:" ); for (Integer integer : difference) System.out.println(integer); SetView <Integer> intersection = Sets.intersection(setA, setB); System.out.println( "intersection:" ); for (Integer integer : intersection) System.out.println(integer); // Map 的更多操作 Map<String, String> mapA = ImmutableMap.of("k1", "v1", "k2", "v2", "k3", "v3" ); Map <String, String> mapB = ImmutableMap.of("k2", "v2", "k3", "v3", "k4", "v4" ); MapDifference <String, String> differenceMap = Maps.difference(mapA, mapB); differenceMap.areEqual(); Map entriesDiffering = differenceMap.entriesDiffering(); Map entriesOnlyOnLeft = differenceMap.entriesOnlyOnLeft(); Map entriesOnlyOnRight = differenceMap.entriesOnlyOnRight(); Map entriesInCommon = differenceMap.entriesInCommon(); System.out.println(entriesDiffering); System.out.println(entriesOnlyOnLeft); System.out.println(entriesOnlyOnRight); System.out.println(entriesInCommon); // 使用Preconditions进行校验，校验不通过会抛出相应的异常 Test t = new Test("Tite", new Date(), "Author" ); // Multimap的使用，Multimap<T1, T2>,T1表示Map的键，T2表示Value集合的集合元素类型 Map<String, List<Man>> map = new HashMap<String, List<Man>> (); public void addMan1(String author, Man Man) { List <Man> Mans = map.get(author); if (Mans == null ) { Mans = new ArrayList<Man> (); map.put(author, Mans); Mans.add(Man); // 使用Multimap替代以上代码 Multimap<String, Man> multimap = ArrayListMultimap.create(); public void addMan2(String name, Man man) { multimap.put(name, man); // Multimap的高级应用 // listOfMaps代表一个List中包含多个这种 mapOf("type", "blog", "id", "292", "author", "john"); 类型的Map // 现在需要根据type将这些map放在不同的list中 List listOfMaps = null ; // 这里省略 listOfMaps 的初始化 Multimap<String, Map<String, String>> partitionedMap = Multimaps.index( listOfMaps, new Function<Map<String, String>, String> () { public String apply( final Map<String, String> from) { return from.get("type" ); // 使用Preconditions进行校验 public Test(String title, Date date, String author) { this .title = Preconditions.checkNotNull(title); this .date = Preconditions.checkNotNull(date); this .author = Preconditions.checkNotNull(author);