Java java.lang.ref.SoftReference用法及代碼示例

// Java program to show the demonstration
// of get() method of SoftReference Class
import java.lang.ref.SoftReference;
class GFG {
    public static void main (String[] args) {
       
        // creating a strong object of MyClass
          MyClass obj = new MyClass ();
       
          // creating a weak reference of type MyClass
          SoftReference<MyClass> sobj = new SoftReference<>(obj);
       
          System.out.println ("-> Calling Display Function using strong object:");
          obj.Display ();    
       
          System.out.println ("-> Object set to null");
       
          obj = null;
       
        // Calling the get() method
          obj = sobj.get();
          System.out.println ("-> Calling Display Function after retrieving from soft Object");
          obj.Display ();
    }
}
class MyClass {
      void Display () 
    {
        System.out.println ("Display Function invoked ...");
    }
}

// Java program demonstrating all the methods
// of SoftRefernce Class
import java.lang.ref.SoftReference;
class GFG {
    public static void main (String [] args) {
      
        // Creating object of Class X
        X obj = new X ();
       
        // Creating a soft reference of type X
          SoftReference <X> softobj = new SoftReference <X> (obj);
       
          System.out.println ("-> Retrieving object from Soft Reference using get ()");
          softobj.get().show();
       
          System.out.println ("-> Is it possible to queue object using enqueue ()");
          System.out.println (softobj.enqueue ());
       
          System.out.println ("-> Checking if reference is queued using isEnqueued ()");
          System.out.println (softobj.isEnqueued ());
    }
}
class X {
    void show() 
    {
        System.out.println ("show () from X invoked..");
    }
}