package guava; import java.io.File; import java.io.IOException; import java.util.ArrayList; import java.util.Comparator; import java.util.Date; import java.util.HashMap; import java.util.HashSet; import java.util.List; import java.util.Map; import java.util.Set; 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); } }
