Guava 사용 요약 슬라이드.

이 슬라이드를 보고 암이 치료되었습니다...

위 슬라이드 내용을 아래와 같이 정리해 봤다.

Base :: Objects.equal(), Objects.hashCode(), 

            MoreObjectes.toStringHelper(), ComparisonChain.compare()

public class Employee implements  Comparable{
    public String name;
    public Integer age;
    public Job job;

    @Override
    public boolean equals(Object o) {
        if(!(o instanceof  Employee)) return false;
        Employee that = (Employee)o;
        return Objects.equal(name, that.name) &&
                Objects.equal(age, that.age) &&
                job == that.job;
    }

    @Override
    public int hashCode() {
        return Objects.hashCode(name, age, job);
    }

    @Override
    public String toString() {
        return MoreObjects.toStringHelper(this).
                add("name", name).
                add("age", age).
                add("job", job).
                toString();
    }


    @Override
    public int compareTo(Employee another) {
        return ComparisonChain.start()
                .compare(this.name, another.name, 
                                Ordering.natural().nullsLast())
                .compare(this.age, another.age, 
                                Ordering.natural().nullsLast())
                .compare(this.job, another.job, 
                                Ordering.natural().nullsLast())
                .result();
    }
}

Base :: Preconditions.checkNotNull()

public class Mail {
    String title;
    String body;

    public Mail(String title, String body) {
        this.title = Preconditions.checkNotNull(title, "title must not be null");
        this.body = Preconditions.checkNotNull(body, "body must not be null");
        Preconditions.checkArgument(body.matches("<[^>]*>"), "Cannot insert tags in body."  );
        Preconditions.checkArgument(title.matches("<[^>]*>"), "Cannot insert tags in title"  );
    }
}


// java.lang.NullPointerException: title must not be null 발생.
Mail mailA = new Mail(null, null);

// java.lang.IllegalArgumentException: Cannot insert tags in body. 발생.
Mail mailB = new Mail("ha ha!","hi <div> hello </div> " );

더 많은 정보 : http://stackoverflow.com/questions/3128120/what-is-the-proper-error-message-to-supply-to-google-guavas-preconditions-met

Base :: MoreObjects.firstNonNull()

public String getPackageName() {
    // 기존
    //String packageName = getPackageName();
    //return (packageName != null)?packageName:"UNKNOWN";

    // 개선
    return MoreObjects.firstNonNull(getPackageName(), "UNKNOWN");
}

Base :: Joiner

List<String> heroes = Lists.newArrayList("Kick-Ass", "Iron Man", null, "Chuck Norris");
String names = Joiner.on(", ").join(heroes);
// NullPointerException 발생!!

List<String> heroes = Lists.newArrayList("Kick-Ass", "Iron Man", null, "Chuck Norris");
String names = Joiner.on(", ").skipNulls().join(heroes);
// "Kick-Ass, Iron Man, Chuck Norris"

List<String> heroes = Lists.newArrayList("Kick-Ass", "Iron Man", null, "Chuck Norris");
String names = Joiner.on(", ").useForNull("Invisible Man").join(heroes);
// prints "Kick-Ass, Iron Man, Invisible Man, Chuck Norris"

Map<Integer, String> map = new HashMap<Integer, String>();
map.put(1, "Chuck Norris");
map.put(2, "Iron Man");
map.put(3, "Kick-Ass");
String ranks = Joiner.on('\n').withKeyValueSeparator(" -> ").join(map);

System.out.println(ranks);

/**
Prints:
1 -> Chuck Norris
2 -> Iron Man
3 -> Kick-Ass
*/

정리중...