全面解析java final关键字

import java.util.*;

class Value {
  int i;
  Value(int i) {
    this.i = i;
  }
}

/**
 * @author Limh
 */
public class FinalData {
  private static Random rand = new Random(47);
  private String id;

  public FinalData(String id) {
    this.id = id;
  }
  private final int valueOne = 9;
  private static final int VALUE_TWO = 99;
  public static final int VALUE_THREE = 39;
  private final int i4 = rand.nextInt(20);
  static final int INT_5 = rand.nextInt(20);
  private Value v1 = new Value(11);
  private final Value v2 = new Value(22);
  private static final Value VAL_3 = new Value(33);
  private final int[] a = {1, 2, 3, 4, 5, 6};

  @Override
  public String toString() {
    return id + ": " + "i4 = " + i4 + ", INT_5 = " + INT_5;
  }

  public static void main(String[] args) {
    FinalData fd1 = new FinalData("fd1");
    //v2=new Value(22);
    fd1.v2.i++;
    fd1.v1 = new Value(9);
    //a.length = 6
    for (int i = 0; i < fd1.a.length; i++) {
      fd1.a[i]++;
    }
    System.out.println(fd1);
    System.out.println("Creating new FinalData");
    FinalData fd2 = new FinalData("fd2");
    System.out.println(fd1);
    System.out.println(fd2);
  }
}

fd1: i4 = 15, INT_5 = 18
Creating new FinalData
fd1: i4 = 15, INT_5 = 18
fd2: i4 = 13, INT_5 = 18

class Gizmo {
  public void spin() {

  }
}

/**
 * @author Limh
 */
public class FinalArguments {
  void with(final Gizmo g) {
    //-g = new Gizmo(); 
    // Illegal -- g is final
  }

  void without(Gizmo g) {
    g = new Gizmo(); // OK -- g is not final
    g.spin();
  }

  //void f(final int i) { i++; } // Can't change
  // You can only read from a final primitive
  int g(final int i) {
    return i + 1;
  }

  public static void main(String[] args) {
    FinalArguments bf = new FinalArguments();
    bf.without(null);
    bf.with(null);
  }
}