How to prevent an object from getting garbage collected?

We have three ways to achieve same - 1) Increasing the Heap -Eden space size . 2) Create Singleton class with Static reference . 3) Override finalize() method and never let that object dereference.

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; 
       } 
   
   }