[JAVA]자바 API 보는법 사용법

 

---

 

> API

 java.lang package

 

   Object

docs.oracle.com/javase/8/docs/api/

Java Platform SE 8

   String

 

   StringBuffer

   StringBuilder

   ....

 

   Wraper class : 기본 자료형에 대응되는 클래스형 자료형

    기본 자료형             클래스형(레퍼런스 또는 참조형)자료형

    int                        Integer

    float                      Float

    char                       Character

    double                     Double

    ....                       ....

 

   java.util package

   Random class

   Scanner class

   날짜관련,...

   형식지정,..

   StringTokenizer

   ....

 

   java.text.SimpleDateFormat

 

 

package ex08.apiObject;

class Point{
	
}

public class ObjectClass {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		
		Point pt = new Point();
		System.out.println("point pt information");
		System.out.println("class name :"+pt.getClass());
		System.out.println("hash code :" + pt.hashCode());
		System.out.println("Object String :" + pt.toString());
		System.out.println("Object String :" + pt);
	}

}

package ex08.apiObject;

class Point{
	
}

public class ObjectClass {

	private static final Object Ox15db9742 = null;

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		
		Point pt = new Point();
		System.out.println("point pt information");
		System.out.println("class name :"+pt.getClass());
		System.out.println("hash code :" + pt.hashCode());
		System.out.println("Object String :" + pt.toString());
		System.out.println("Object String :" + pt);
		System.out.printf("10진수 %d\n",Ox15db9742);
		
		System.out.println("===========================");
		Point pt2 = new Point();
		System.out.println("point pt information");
		System.out.println("class name :"+pt2.getClass());
		System.out.println("hash code :" + pt2.hashCode());
		System.out.println("Object String :" + pt2.toString());
		System.out.println("Object String :" + pt2);
		System.out.println("#############################");

		System.out.println("p2.toString() : toString()의 의미");
		System.out.println(pt2.getClass().getName() + '@'+ Integer.toHexString(pt2.hashCode()));
		
		Point pt3 = new Point();
		
		if(pt.hashCode()== pt3.hashCode()) {
			System.out.println("같다");
		}else {
			System.out.println("다르다");
		}
		
	}

}

---