나만의 코딩기록

Object objToString = "test";
String str1 = objToString.toString();
String str2 = String.valueOf(objToString);
String str3 = (String) objToString;

System.out.println("str1 = " + str1);
System.out.println("str2 = " + str2);
System.out.println("str3 = " + str3);

Object nullObjToString = null;
//String str4 = nullObjToString.toString();
//System.out.println("str4 = " + str4);
String str5 = String.valueOf(nullObjToString);
System.out.println("str5 = " + str5);
String str6 = (String) nullObjToString;
System.out.println("str6 = " + str6);


Object objToInt = 3;
int int1 = Integer.parseInt(objToInt.toString());
int int2 = (int) objToInt;

System.out.println("int1 = " + int1);
System.out.println("int2 = " + int2);

/** result
str1 = test
str2 = test
str3 = test
str5 = null
str6 = null
int1 = 3
int2 = 3 **/

object to String 결론

• .toString() NPE 발생
• .valueOf()
• (String) 예외 없이 모든 참조 유형에 널을 캐스팅할 수 있다. (추후체크)
• (String)에 관한 StackOverflow