Groovy集合(list)

声明list

list = [1,2,3]list = (1..3).toList()  //range转换为listassert list == [1,2,3]assert list[1] == 2assert list instanceof java.util.Listlist[1] = 12assert list == [1,12,3]longList = (0..100)assert longList[22] == 22

list操作符

下标操作符

/**     GDK使用range 和 collection作为参数重载了getAt()方法，这样就可以使用范围和索引的集合访问list*/list = [1,2,3,4]assert list[0..2] == [1,2,3]    //使用range访问listassert list[0,2] ==[1,3]    //使用集合访问listlist[0..2] = ['x','y','z']assert list == ['x','y','z',4]//当范围作为下标时，数量不一定要相等，当指定的列表值小于或者为空时，列表收缩//当指定的列表值更大时，列表增长list = [1,2,3,4]list[1..2] = []assert list == [3,4] list = [1,2,3,4]list[1..1] = [1,2]assert list == [1,1,2,3,4]//list可以通过负数进行索引//-1表示最后一个。-2表示倒数第二个，以此类推list = (0..3).toList()assert list[-1] == 3 //当范围反向时，结果列表也是反向的assert list[3..0] == [3,2,1,0]    //正负数可以一起使用 下式可以去掉开头和最后的元素assert list[1..-2] == [1,2]

增删list中的元素

//+ plus方法list = []list += 1        //plus(Object)list += [2,3]        //plus(Collection)assert list == [1,2,3]list += (4..5) assert list == [1,2,3,4,5]//<< leftShift()方法list << 6 <<7        //leftShift(Object)assert list == [1,2,3,4,5,6,7]list << [8,9]assert list == [1,2,3,4,5,6,7,[8,9]]list = [1,2,3]list << (4..5)  //4..5 字符串assert list == [1,2,3,4..5]//- minus()方法list = [1,2,3,4,5,6]assert list -= [5,6] == [1,2,3,4]  assert list -= （3..4）   == [1,2]assert list*2 == [1,2,1,2]         //multiply(Object)

list方法

//add()类似于<<，但返回布尔值list = [1,2,3]list.add(4)assert list == [1,2,3,4]list = [1,2,3]list.add(1,4)assert list == [1,4,2,3]    //在给定索引处插入新值list = [1,2,3]list.add([4,5])assert list == [1,2,3,[4,5]]list = [1,2,3]list.add((1..2))assert list == [1,2,3,1..2]//addAll()类似于+，返回布尔值。list = [1,2,3]list.addAll([4,5])assert list == [1,2,3,4,5]list = [1,2,3]list.addAll((4..5))assert list == [1,2,3,4,5]//get()  getAt()assert [1,2,3].get(1) == 2assert [1,2,3].getAt([1,2]) == [2,3]    //返回指定索引段的新列表assert [1,2,3].getAt((0..1)) == [1,2]assert  [].isEmpty()    //判断列表是否为空assert [1,2,3].intersect([2,3]) == [2,3]    //取交集，参数只能为列表assert [1,2,3,4].disjoint([1])    //判断是否有交集 有则返回false；assert [1,2,[3,4]].flatten() == [1,2,3,4]   //打开嵌套的列表assert [1,2,1,3].unique() == [1,2,3]    //去重assert new HashSet([1,2,3,1,1,1]).toList() == [1,2,3]    //去重assert [1,2,3,4].reverse() == [4,3,2,1]    //反转assert [1,5,3,7].sort() == [1,3,5,7]    //升序//对map组成的list进行排序def list = [[a:11],[a:3],[a:5]]assert list.sort{a,b-> return (a.a).compareTo(b.a)} == [[a:3], [a:5], [a:11]]assert [1,5,3,7].sort{a,b -> b<=>a} == [7,5,3,1]   //降序assert [1,2,3,1,1].count(1) == 3    //计算包含元素的个数assert list.join('-') == '1-2-3'    //把所有的元素用给定字符串连接assert list.join('') == '123'[1,2,3,1,1,1].sum()    //求和[1,2,3,1,1,1].max()    //求最大值[1,2,3,1,1,1].min()    //求最小值//every() 所有的element都满足条件才返回true，否则返回falseassert list.every{it -> it<5}//any() 只要存在一个满足条件的element就返回true，否则返回falseassert list.any{it -> it>2}//像堆栈(stack)一样使用 push操作由<<代替 返回被删除的值assert [1,2,3].pop()assert [1,2,3].push(4)  //返回布尔值//通过下标删除元素 返回被删除的值assert [1,2,3,4].remove(2) == [1,2,4] //通过值删除符合条件的一个元素   返回布尔值assert [1,'2',3,4].remove('2')   assert [1,'2',3,1,1,1].removeAll(['2',3])    //删除所有符合条件的元素//grep() 符合条件的element会被提取出来，形成一个listdef list = ['a', 'ab', 'abc']assert list.grep { elem -> elem.length()<3} == ['a','ab']   //条件以闭包形式传入assert ["ab"] == list.grep(~/../)  //条件以regex形式传入assert ["a","ab"] == list.grep(['a', 'cde', 'ab'])  //条件以列表形式传入//each() 遍历liststore = '' [1,2,3].each{it -> store += it}assert store == '123'//eachWithIndex() 带index的eachdef list = []['a', 'b', 'c'].eachWithIndex { elem, i ->list << "${elem}${i}"}assert list == ["a0","b1","c2"]//find()  findAll()返回符合条件的所有元素,def list = [1, 2, 3, 4]assert list.find{it -> it%2 ==0} ==2 //返回符合条件的一个元素assert list.findAll{it -> it%2 ==0} == [2,4]assert [1,2,3,4].findAll{it>2?it*2:null} == [3,4]   //但不能改变元素//collect() 对集合每个元素进行运算后,得到一个新集合def list = [1, 2, 3, 4]assert [2,4,6,8] == list.collect{it*2}assert [1,2,3].collect{if(it > 1){"a"}} ==   [null, 'a','a']    //返回每个元素,即使没有指定值.assert [1,2,2,3].collect(new HashSet()){it*2}  == [2,4,6] as Set    //指定集合的类型//findResults() 使用提供的闭包迭代Iterable变换项，并收集任何非空结果 assert  [1,2,3].findResults { it > 1 ? "Found $it" : null } == ["Found 2", "Found 3"]//collectEntries() 对list的每一个元素进行一定格式的转换,返回map.可以指定初始值.assert [1,10,100,1000].collectEntries{[it,it.toString().size()]}  ==  [1:1, 10:2, 100:3, 1000:4] assert [1,10,100,1000].collectEntries{if(it>11){[it,it.toString().size()]}else{[it.toString().size(),it] }} == [1:1, 2:10, 100:3, 1000:4]   //必须返回每一个元素 assert  [1,10,100,1000].collectEntries([11:1]){[it,it.toString().size()]}   ==   [11:1, 1:1, 10:2, 100:3, 1000:4] //可以指定初始值.//groupBy() 对collection中的element按给定条件进行分组def list = ['a', 'b', 'abc', 'ab', 'c', 'bc']assert [1:["a","b","c"],3:["abc"],2:["ab","bc"]] == list.groupBy { elem ->    elem.length()}//inject()方法遍历集合，第一次将传递的值和集合元素传给闭包，将处理结果作为传递的值，和下一个集合元素传给闭包，依此类推result = list.inject(5){a,b -> a+=b}assert result == 5 + 1+2+3//transpose()方法实际上就是数学中矩阵的转置，简单的来说就是行和列的交换。如果List的长度不一，则取最短的长度def list41 = [1, 1, 1]  def list51 = [2, 2]  assert [[1, 2], [1, 2]] == [list41, list51].transpose()

tokenize() vs split()

//1.split()返回string[]， tokenize()返回list//2.tokenize()忽略空字符串String testString = 'hello brother'assert testString.split() instanceof String[]assert ['hello','brother']==testString.split() assert['he','','o brother']==testString.split('l')assert testString.tokenize() instanceof Listassert ['hello','brother']==testString.tokenize() assert ['he','o brother']==testString.tokenize('l')//3.tokenize()使用字符串内的所有字符String  testString1='hello world'assert ['hel',' world']==testString1.split('lo')assert ['he',' w','r','d']==testString1.tokenize('lo')//4.split()可以使用正则表达式String testString2='hello world 123 herload'assert['hello world ',' herload']==testString2.split(/\d{3}/)

集合应用

//    根据list内的map数组元素的元素有条件的去重,对name进行去重，age尽量不为空def list =  [['name':"zhangsan",'age':null],['name':"zhangsan",'age':23],['name':"lisi",'age':null],['name':"lisi",'age':20],['name':"lisi",'age':null],['name':"wangwu",'age':null]]def ref = [];list.each{    if(it.name in ref['name']){       name =it.name;       age  = it.age;       ref.each{            if(it.name == name && it.age == null){                ref -= ["name":it.name,"age":it.age]                ref += ["name":name,"age":age]                       }        }    }else{        ref += ["name":it.name,"age":it.age]    }}assert ref == [[name:zhangsan, age:23], [name:lisi, age:20], [name:wangwu, age:null]]