How to prevent an object from getting garbage collected?

Question

How to prevent an object from getting garbage collected?

Are there any approaches by finalize or phantom reference or any other approaches?

I was asked this

Answer 1

There are 3 ways to prevent an Object from Garbage Collection as following:-

1. Increase the Heap Size of JVM

   // Xms specifies initial memory to be allocated
   // and Xmx specifies maximum memory can be allocated
   java -Xms1024m -Xmx4096m ClassFile
   

2. Use a SingleTon Class Object as @Tobias mentioned

   public class MySingletonClass {
        private static MySingletonClass uniqueInstance;
   
        // marking constructor as private
        private MySingletonClass() {
        }
   
        public static synchronized MySingletonClass getInstance() {
           if (uniqueInstance == null) {
               uniqueInstance = new Singleton();
           }
           return uniqInstance;
       }
   }
   

3. We can override finalize method. That is last method executed on an object. Hence, it will remain in memory.

   // using finalize method 
   class MyClassNotGc{ 
   
       static MyClassNotGc staticSelfObj; 
   
       pubic void finalize() { 
           // Putting the reference id 
           //Object reference saved. 
           //The object won't be collected by the garbage collector
           staticSelfObj = this; 
       } 
   
   }