guava:Lists、Sets、Maps和Collections2的使用

1.Lists

System.out.println("### Lists ###");
ArrayList<String> arrayList = Lists.newArrayList();
arrayList.add("A");
arrayList.add("B");
arrayList.add("C");
System.out.println(arrayList);

LinkedList<String> linkedList = Lists.newLinkedList();
linkedList.add("A");
linkedList.add("B");
linkedList.add("C");
System.out.println(linkedList);

System.out.println(Lists.reverse(arrayList)); //翻转集合元素的顺序
System.out.println(Lists.reverse(linkedList));

System.out.println(Lists.partition(arrayList, 2)); //一个集合内再分成n个子集合

 

2.Sets

//Sets  

System.out.println("### Sets ###");  

HashSet<String> set1 = Sets.newHashSet();  

set1.add("A");  

set1.add("B");  

set1.add("C");  

LinkedHashSet<String> set2 = Sets.newLinkedHashSet();  

set2.add("B");  

set2.add("C");  

set2.add("D");  

set2.add("E");  

//Sets.newTreeSet();  

//Sets.newConcurrentHashSet();  

System.out.println(Sets.union(set1, set2)); //返回两个集合的并集  >> [A, B, C, D, E]  

System.out.println(Sets.difference(set1, set2)); //返回set1中不存在于set2的元素集合  >> [A]  

System.out.println(Sets.intersection(set1, set2)); //返回两个集合的交集  >> [B, C]  

Set<String> resultSet = Sets.filter(set2, new Predicate<String>() {  

@Override  

public boolean apply(String value) {  

return !"D".equals(value); //过滤掉值为D的元素  >> [B, C, E]  

    }  

});  

System.out.println(resultSet);  

 

3、Maps

//Maps
System.out.println("### Maps ###");
Maps.newHashMap();
Maps.newLinkedHashMap();
Maps.newTreeMap();
Maps.newConcurrentMap();

4、Collections2

//Collections2
System.out.println("### Collections2 ###");
Collection<String> linkedList2 = Collections2.filter(linkedList, new Predicate<String>() {
@Override
public boolean apply(String value) {
return !"B".equals(value); //过滤器：过滤掉值为B的元素 >> [A, C]
}
});
System.out.println(linkedList2);

Collection<String> linkedList3 = Collections2.transform(linkedList, new Function<String, String>() {
@Override
public String apply(String value) {
return value + "_"; //转换器：元素值做特殊处理后返回 >> [A_, B_, C_]
}
});
System.out.println(linkedList3);