guava常用简化操作

1.hashcode计算及对象比较：Objects.hashCode(),ComparisonChain链式比较

    @Override
    public int hashCode() {
        return Objects.hashCode(id,name,type);
    }
    @Override
    public int compareTo(Program o) {
        int result = ComparisonChain.start()
                .compare(this.name, o.getName())
                .compare(this.id, o.getId())
                .compare(this.type, o.getType())
                .result();
        return result;
    }

2.List与字符串互相转换

        List<String>list= ImmutableList.of("1","2","3","4");
        String concat=Joiner.on(",").join(list);
        //输出1,2,3,4
        String split="this is an split string ";
        List<String>splitList=Splitter.on(" ").omitEmptyStrings().trimResults().splitToList(split);
        //输出[this,is,an,split,string]

3.过滤器filter+transform
   实例1：在list中查找某个对象

        Program p = Iterables.filter(programList, new Predicate<Program>() {
            @Override
            public boolean apply(Program program) {
                return program.getName().equals(name);
            }
        }).iterator().next();

    实例2：提取list中对象的属性值list   

        Iterable<String>nameIt=Iterables.transform(programList, new Function<Program, String>() {
            @Override
            public String apply(Program program) {
                return program.getName();
            }
        });
        List<String>nameList=Lists.newArrayList(nameIt);