在Java 8中将List转换为Map对象方法

<b>public</b> <b>class</b> Employee {
  <font><i>// member variables</i></font><font>
  <b>private</b> <b>int</b> empId;
  <b>private</b> String empName;
  <b>private</b> <b>int</b> empAge;
  <b>private</b> String empDesignation;
</font>

 <font><i>// convert List<Employee> to Map<empId, empName> using Java 8 Streams</i></font><font>
 Map<Integer, String> mapOfEmployees = employees.stream().collect(
    Collectors.toMap(e -> e.getEmpId(),e -> e.getEmpName()));
</font>

 <font><i>// convert List<Employee> to Map<empId, empName> using Java 8 Streams</i></font><font>
Map<Integer, Employee> mapOfEmployees = employees.stream().collect(
        Collectors.toMap( e -> e.getEmpId(), e -> e));
</font>

Map<Integer, String> mapOfEmployees = employees.stream().collect(
        Collectors.toMap(
            e -> e.getEmpId(), 
            e -> e.getEmpName(), 
            (e1, e2) -> e1 )); <font><i>// Merge Function</i></font><font>
</font>

 Map<Integer, String> mapOfEmployees = employees.stream().collect(
        Collectors.toMap(
            e -> e.getEmpId(), 
            e -> e.getEmpName(), 
            (e1, e2) -> e1 , <font><i>// Merge Function</i></font><font>
            TreeMap<Integer, String>::<b>new</b>)); </font><font><i>// Map Supplier</i></font><font>
</font>

() -> new TreeMap<Integer, String>(new MyComparator())