Guava 다시 - 3

3. Function & Predicate

package com.tisotry.tazz009.guava; import java.util.List; import com.google.common.base.Function; import com.google.common.base.Predicate; import com.google.common.collect.ImmutableList; import com.google.common.collect.Iterables; public class FunctionTest { public static void main(String[] args) { } List<String> getDesignerNames(List<Employee> employees) { // Step 1. // List<String> names = new ArrayList<String>(); // // for (Employee employee : employees) { // if (employee.getJob() == Job.DESIGNER) { // names.add(employee.getName()); // } // } // // return names; // Step 2. // Iterable<Employee> designers = Iterables.filter(employees, new Predicate<Employee>() { // // @Override // public boolean apply(Employee employee) { // return employee.getJob() == Job.DESIGNER; // } // }); // // Iterable<String> names = Iterables.transform(designers, new Function<Employee, String>() { // // @Override // public String apply(Employee employee) { // return employee.getName(); // } // // }); // // return ImmutableList.copyOf(names); // Step 3. Iterable<Employee> designers = Iterables.filter(employees, new EmployeeJobPredicate(Job.DESIGNER)); Iterable<String> names = Iterables.transform(designers, new EmployeeNameFunction()); return ImmutableList.copyOf(names); } public class EmployeeNameFunction implements Function<Employee, String> { @Override public String apply(Employee employee) { return employee.getName(); } } public class EmployeeJobPredicate implements Predicate<Employee> { private final Job job; public EmployeeJobPredicate(Job job) { this.job = job; } @Override public boolean apply(Employee employee) { return employee.getJob() == job; } } public class Employee { private String name; private Integer age; private Job job; public String getName() { return name; } public void setName(String name) { this.name = name; } public Integer getAge() { return age; } public void setAge(Integer age) { this.age = age; } public Job getJob() { return job; } public void setJob(Job job) { this.job = job; } } public enum Job { CEO, DEVELOPER, DESIGNER } }