如何使用List <object>的IndexOf()方法

Question

我在使用该IndexOf()方法时看到的所有示例List<T>都是基本字符串类型.我想知道的是如何根据一个对象变量返回作为对象的列表类型的索引.

List<Employee> employeeList = new List<Employee>();
employeeList.Add(new Employee("First","Last",45.00));

我想找到索引在哪里 employeeList.LastName == "Something"

Answer 1

int index = employeeList.FindIndex(employee => employee.LastName.Equals(somename, StringComparison.Ordinal));

编辑:没有用于C#2.0的lambdas(原始版本不使用LINQ或任何.NET 3+功能,只是C#3.0中的lambda语法):

int index = employeeList.FindIndex(
    delegate(Employee employee)
    {
        return employee.LastName.Equals(somename, StringComparison.Ordinal);
    });

Answer 2

public int FindIndex(Predicate<T> match);

使用lambdas:

employeeList.FindIndex(r => r.LastName.Equals("Something"));

注意:

// Returns:
//     The zero-based index of the first occurrence of an element
//     that matches the conditions defined by match, if found; 
//     otherwise, –1.

Answer 3

你可以通过覆盖Equals方法来做到这一点

class Employee
    {
        string _name;
        string _last;
        double _val;
        public Employee(string name, string last, double  val)
        {
            _name = name;
            _last = last;
            _val = val;
        }
        public override bool Equals(object obj)
        {
            Employee e = obj as Employee;
            return e._name == _name;
        }
    }