Thinking in Java

Cleanup: finalization (finialize()) and garbage collection 

1. Your object might not get garbage collected 
2. Garbage collection is not destruction 
3. Garbage collection is only about memory

Force garbage collection:

System.gc();

use of finalize:

protected void finalize(){

  if(some conditions)

      errorMessage;

}

Array 

int[] a; 

Random rand = new Random(47); 

a = new int[rand.nextInt(20)]; 

Inner Class

inner class and surrounding class 

public class Parcel1 { class Contents { //protected, also can be + -; private int attribute; public int method() { return 0; } }

OuterClassName.InnerClassName

Out.Inner inner = out.getInner(); 

In addition, inner classes have access rights (link) to all the elements in the enclosing class. (different from C++ which does not have links) 

done