Effective Java 3rd - Chapter08. 메서드

public void foo() {}
public void foo(int a1) {}
public void foo(int a1, int a2) {}
public void foo(int a1, int a2, int a3) {}
public void foo(int a1, int a2, int a3, int... rest) {}

public List<Cheese> getCheeses() {

	// Collections.emptyList()는 불변 리스트 객체를 리턴한다.
	return cheesesInStock.isEmpty() ? Collections.emptyList() : new ArrayList<>(cheessesInStock);
}

// 옵셔널 활용1 - null일 경우, 기본값을 정해둘 수 있다.
String lastWordInLexicon = max(words).orElse("단어 없음..");

// 옵셔널 활용2 - 원하는 예외를 던질 수 있다.
Toy myToy = max(toys).orElseThrow(ToysException::new)

/**
* Returns the element at the specified position in this list.
*
* <p>This method is <i>not</i> guaranteed to run in constant
* time. In some implementations it may run in time proportional
* to the element position.
*
* @param  index index of element to return; must be
*         non-negative and less than the size of this list
* @return the element at the specified position in this list
* @throws IndexOutOfBoundsException if the index is out of range
*         ({@code index < 0 || index >= this.size()})
*/
E get(int index) {
	return null;
}

/**
* Returns true if this collection is empty.
*
* @implSpec This implementation returns {@code this.size() == 0}.
*
* @return true if this collection is empty
*/
public boolean isEmpty() {
	return false;
}

/**
* An object that maps keys to values.  A map cannot contain duplicate keys;
* each key can map to at most one value. 
*
* @param <K> the type of keys maintained by this map
* @param <V> the type of mapped values
*/
public interface Map<K,V> {
	...
}

/**
* An instrument section of a symphony orchestra.
*/
public enum OrchestraSection {
	/** Woodwinds, such as flute, clarinet, and oboe. */
	WOODWIND,

	/** Brass instruments, such as french horn and trumpet. */
	BRASS,

	/** Percussion instruments, such as timpani and cymbals. */
	PERCUSSION,

	/** Stringed instruments, such as violin and cello. */
	STRING;
}

/**
* Indicates that the annotated method is a test method that
* must throw the designated exception to pass.
*/
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public @interface ExceptionTest {
	/**
	* The exception that the annotated test method must throw
	* in order to pass. (The test is permitted to throw any
	* subtype of the type described by this class object.)
	*/
	Class<? extends Throwable> value();
}