studentNew进行判断是否已经在list中，学生的唯一标识是id，不考虑其他，就是单纯的用Java代码判断，此时就需要将List转为Map，代码如下： Map studentMap...= list.stream().collect(Collectors.toMap(Student::getId, Function.identity())); if(studentMap.containsKey...; } 将Map转为List就非常简单了: List listValues = new ArrayList(studentMap.values()); //map...values List listKeys = new ArrayList(studentMap.keySet()); //map keys 2.List To Set...()); //map keys Set mapToSetValues = new HashSet(studentMap.values()); //map values
先看下怎么创建Map： // 创建map var studentMap = { 'name': 'jack', 'age': '18', 'class': 'class one' };...var teacherMap = Map(); var teacherMap2 = Map(); 添加和删除： var studentMap =Map(); studentMap.putIfAbsent...('name', ()=>'jack'); studentMap.remove('name'); 判断map中是否包含某个key可以使用containsKey()： assert(studentMap.containsKey...('name')); 常见的集合方法 集合中最常见的方法就是判断集合是否为空： assert(studentMap.isEmpty); assert(studentMap.isNotEmpty); 如果想对集合中的每个元素都进行某个函数操作
= sdcFunctions.createMap(true); studentMap.no = records[i].value['no']; studentMap.school...= records[i].value['school']; studentMap.class = records[i].value['class'];...studentMap.address = records[i].value['address']; studentMap.name = students[j].name;...studentMap.teacher = students[j].teacher; studentMap.age = students[j].age; newRecord.value...= studentMap; log.info("-------------" + newRecord.value['school']) output.write
:= make(map[string]map[string]string) // 初始化整个map studentMap["stu01"] = make([string]string, 3)...// 整个map的值也是个map，需要进行初始化；3表示三个信息 studentMap["stu01"]["name"] = "Tom" studentMap["stu01"]["sex"...] = "男" studentMap["stu01"]["address"] = "深圳" studentMap["stu02"] = make([string]string, 3) /.../ 整个map的值也是个map，需要进行初始化；3表示三个信息 studentMap["stu01"]["name"] = "Jackson" studentMap["stu01"]["sex"...] = "男" studentMap["stu01"]["address"] = "广州" } map 之增删改查crud key不存在就是增加，存在就是修改； 删除delete(map, “key
mapper.dtd"> ... ...--由于我们只要查询学生的名字，而我们的实体studentMap可以封装学生的名字，那么我们返回studentMap即可，并不需要再关联到学科表--> select s.sname,s.sid from zhongfucheng.students
String[] args) { -------------------- before -------------------- Map studentMap...= new HashMap(); studentMap.put("张三", "男"); studentMap.put("小红", "女"); studentMap.put...("李四", "男"); studentMap.forEach((name, sex) -> { System.out.println(name + " : "
student.setId(11); student.setAge(21); student.setName("全栈学习笔记"); Map studentMap...= new HashMap(); studentMap.put(11,student); return studentMap.get(id); } } 其中...public Map AddStudent(@RequestBody Student student){ Map studentMap...= new HashMap(); studentMap.put(student.getId(),student); return studentMap; }
JDK8提供的Stream虽然好用，Lambda虽然简洁，但一定不能滥用，我举一个实际遇到的例子（已做脱敏处理）： Map> studentMap = students.stream...Map> studentMap = students.stream().collect(Collectors.groupingBy(Student::getStudentNumber...Map>> studentMap = new TreeMap(); for (Student student : students) { List<Student
studentDao.listStudents(); }}3、创建事件监听@Componentpublic class StudentCache { private Map studentMap...= null){ studentEntityList.forEach(studentEntity -> { studentMap.put...studentEntity.getSId(), studentEntity); }); } } System.out.println(studentMap
SELECT * from student where name=#{name}...//记住美元符号where条件后的拼接字段要加引号 select...第一步：接口 List selectTable(String table); 第二步 ：映射文件
字符串类型Map集合 private Map students3; // 对象类型map集合 private Map studentMap...{ return students3; } public void setNames2(Map names2) { this.studentMap...", students2=" + students2 + ", students3=" + students3 + ", studentMap...=" + studentMap + ", properties=" + properties + " ]"; }}准备测试方法 /
namespace="day_8_mybatis.mapper.StudentMapper"> 6 16 17 18 21 22 25 26 <resultMap id="femaleStudentMap" type="day_8_mybatis.pojo.FemaleStudent" extends="<em>studentMap</em>
com.example.demomybatis.dao.StudentDao"> select id, name, age...--查询指定行数据--> select id, name...--通过实体作为筛选条件查询--> select id, name
new RichMapFunction[(Int, String, Int), (String, String, Int)] { // 定义获取学生数据集的集合 var studentMap...String)] = getRuntimeContext.getBroadcastVariable[(Int, String)]("student") studentMap...//返回值类型(学生名字，学科名，成绩) val stuId: Int = value._1 val stuName: String = studentMap.getOrElse...scoreDataSet.map( new RichMapFunction[(Int, String, Int), (String, String, Int)] { var studentMap...student") val linesIter: Iterator[String] = Source.fromFile(studentFile).getLines() studentMap
= new HashMap(); // 添加学生信息到哈希映射 studentMap.put("Alice", 85); studentMap.put...("Bob", 92); studentMap.put("Charlie", 78); studentMap.put("David", 90); //...获取学生信息 int aliceScore = studentMap.get("Alice"); System.out.println("Alice's score: "...+ aliceScore); // 更新学生信息 studentMap.put("Alice", 88); aliceScore = studentMap.get...()) { int score = studentMap.get(name); System.out.println(name + "'s score:
字符串类型Map集合 private Map students3; // 对象类型map集合 private Map studentMap...return students3; } public void setNames2(Map names2) { this.studentMap...", students2=" + students2 + ", students3=" + students3 + ", studentMap...=" + studentMap + ", properties=" + properties + " ]"; } } 准备测试方法
mybatis.org/dtd/mybatis-3-mapper.dtd"> <select id="selectUser" resultMap="<em>studentMap</em>
student_card.birthplace FROM student_card WHERE student_card.uid = #{studentId}; <select id="getStudent" parameterType="int" resultMap="<em>studentMap</em>
TeacherName { get; set; } public virtual ICollection StudentCourses { get; set; } } 3.修改 StudentMap
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