Java函数链

Question

我试图找出以下代码无法编译的原因:

Function<Employee, String> getLastName = (Employee employee) -> {
    return employee.getName().substring(employee.getName().indexOf(" ") + 1);
};

Function<Employee, String> getFirstName = (Employee employee) -> {
    return employee.getName().substring(0, employee.getName().indexOf(" "));
};

Function chained = getFirstName.apply(employees.get(2).andThen(getFirstName.apply(employees.get(2)))); 

不能在java 8中包含所有函数吗？

Answer 1

确切地说,andThen应用于结果Function,例如:

Function<Employee, String> chained = getFirstName.andThen(x -> x.toUpperCase());

x -> x.toUpperCase()(或者可以用方法参考替换String::toUpperCase)应用于Function 的String结果getFirstName.

你怎么想象链接他们？一个人Function回来String,这样就无法连锁.但是您可以通过单个返回这两个字段Function:

 Function<Employee, String[]> bothFunction = (Employee employee) -> {
        String[] both = new String[2];
        both[0] = employee.getName().substring(employee.getName().indexOf(" ") + 1);
        both[1] = employee.getName().substring(0, employee.getName().indexOf(" "));
        return both;
    };