Java에서 객체를 가비지 수집에 적합하게 만드는 방법은 몇 가지입니까?

public class GCTest1 {
   public static void main(String [] args){
      String str = "Welcome to TutorialsPoint"; // String object referenced by variable <strong>str </strong>and it is       not eligible for GC yet.
      str = null; // String object referenced by variable str is eligible for GC.
      System.out.println("str eligible for GC: " + str);
   }
}

str eligible for GC: null

public class GCTest2 {
   public static void main(String [] args){
      String str1 = "Welcome to TutorialsPoint";
      String str2 = "Welcome to Tutorix"; // String object referenced by variable str1 and str2 and         is not eligible for GC yet.
      str1 = str2; // String object referenced by variable str1 is eligible for GC.
      System.out.println("str1: " + str1);
   }
}

str1: Welcome to Tutorix