Guava 开发

Employee.java

package org.yct.demo.guava;

import com.google.common.base.MoreObjects;
import com.google.common.base.Objects;
import static com.google.common.base.Preconditions.*;
import com.google.common.collect.ComparisonChain;
import com.google.common.collect.Ordering;

public class Employee implements Comparable<Employee> {
	private String name;
	private Integer age;
	private Job job;
	
	public Employee() { }
	
	public Employee (String name,int age) {
		this.name = checkNotNull(name, "name 不能为null:", name);
		checkArgument(age > 20, "age 必须大于 20:",age);
		this.age = age;
	}
	
	public String getCoordinatesAsText() {
//		return (getGpsCoordinates() != null) ?  getGpsCoordinates() : "DEFAULT_LOCATION";
		return MoreObjects.firstNonNull(getGpsCoordinates(), "DEFAULT_LOCATION");
	}
	
	private String getGpsCoordinates() {
		// retrieve GPS coordinates from satellite // VERY SLOW!!
		return null;
	}
	
	public int compareTo(Employee other) {
		return ComparisonChain
				.start()
				// 以英文字母(从a到z)的自然顺序，NULL值放在最后
				.compare(this.name, other.name, Ordering.natural().nullsLast())
				// 以数字的反序(从大到小)，NULL值处于最后
				.compare(this.age, other.age, Ordering.natural().reverse().nullsLast())
				.compare(this.job, other.job, Ordering.natural().nullsLast())
				.result();
	}
	
	@Override
	public int hashCode() {
		return Objects.hashCode(name, age, job);
	}
	
	@Override
	public String toString () {
		return MoreObjects.toStringHelper(this)
				.omitNullValues()
				.add("name", name)
				.add("age", age)
				.add("job", job)
				.toString();
	}

	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;
	}
}

guavaDemo.java

    public static void guavaDemo() {
		Employee ee = new Employee("Jhon",22);
		// Employee{name=Jhon, age=22}
		System.out.println(ee.toString());
		// DEFAULT_LOCATION
		System.out.println(ee.getCoordinatesAsText());                          
		
		List<Map<String, Object>> maps = Lists.newArrayList();
		List<Employee> ees = Lists.newArrayList();
		List<String> langs = Lists.newArrayList("中文","English","日本語",null);
		String lang = Joiner.on("|").useForNull("Unkown").join(langs);
		// 中文|English|日本語|Unkown
		System.out.println(lang);                                               
		
		// Like Map<Job, Collection<Employee>>
		Multimap<Job, Employee> multimap = ArrayListMultimap.create();
		multimap.put(Job.CEO, new Employee("Tom",45));
		multimap.put(Job.DESIGNER, new Employee("Jack",24));
		multimap.put(Job.DEVELOPER, new Employee("Alice", 31));
		multimap.put(Job.DEVELOPER, new Employee("Jhone", 25));
		multimap.put(Job.DEVELOPER, new Employee("Jim", 27));
		
		//Map<Job,List<Employee>> jobs = Multimap.
	}

pom.xml

<dependency>
    <groupId>com.google.guava</groupId>
    <artifactId>guava</artifactId>
    <version>18.0</version>
</dependency>

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