package com.iderzheng.finalkeyword;
 
public final class FinalClass {
}
 
// Error: cannot inherit from final
class PackageClass extends FinalClass {
}

import java.lang.reflect.Modifier;
 
public class Main {
 
  public static void main(String[] args) {
    Runnable anonymous = new Runnable() {
      @Override
      public void run() {
      }
    };
 
    System.out.println(Modifier.isFinal(anonymous.getClass().getModifiers()));
  }
}

 false

package com.iderzheng.other;
 
public class FinalMethods {
  public static void publicStaticMethod() {
 
  }
 
  public final void publicFinalMethod() {
  }
 
  public static final void publicStaticFinalMethod() {
  }
 
  protected final void protectedFinalMethod() {
  }
 
  protected static final void protectedStaticFinalMethod() {
  }
 
  final void finalMethod() {
  }
 
  static final void staticFinalMethod() {
  }
 
  private static final void privateStaticFinalMethod() {
  }
 
  private final void privateFinalMethod() {
  }
}
package com.iderzheng.finalkeyword;
 
import com.iderzheng.other.FinalMethods;
 
public class Methods extends FinalMethods {
 
  public static void publicStaticMethod() {
  }
 
  // Error: cannot override
  public final void publicFinalMethod() {
  }
 
  // Error: cannot override
  public static final void publicStaticFinalMethod() {
  }
 
  // Error: cannot override
  protected final void protectedFinalMethod() {
  }
 
  // Error: cannot override
  protected static final void protectedStaticFinalMethod() {
  }
 
  final void finalMethod() {
  }
 
  static final void staticFinalMethod() {
  }
 
  private static final void privateStaticFinalMethod() {
  }
 
  private final void privateFinalMethod() {
  }
}

public String method(final boolean finalParam) {
  // Error: final parameter finalParam may not be assigned
  // finalParam = true;
 
  final Object finalLocal = finalParam ? new Object() : null;
 
  final int finalVar;
  if (finalLocal != null) {
    finalVar = 21;
  } else {
    finalVar = 7;
  }
 
  // Error: variable finalVar might already have been assigned
  // finalVar = 80;
 
  final String finalRet;
  switch (finalVar) {
    case 21:
      finalRet = "me";
      break;
    case 7:
      finalRet = "she";
      break;
    default:
      finalRet = null;
  }
 
  return finalRet;
}

public String method(final Object finalParam) {
  final int finalVar;
  if (finalParam != null) {
    finalVar = 21;
  }
 
  final String finalRet;
 
  // Error: variable finalVar might not have been initialized
  switch (finalVar) {
    case 21:
      finalRet = "me";
      break;
    case 7:
      finalRet = "she";
      break;
  }
 
  // Error: variable finalRet might not have been initialized
  return finalRet;
}

public Runnable method(String string) {
  int integer = 12;
  return new Runnable() {
    @Override
    public void run() {
      // ERROR: needs to be declared final
      System.out.println(string);
      // ERROR: needs to be declared final
      System.out.println(integer);
    }
  };
}

package com.iderzheng.finalkeyword;
 
import java.util.HashSet;
import java.util.LinkedHashSet;
import java.util.Set;
 
public class StaticFinalFields {
  static final int STATIC_FINAL_INIT_INLINE = 7;
  static final Set<Integer> STATIC_FINAL_INIT_STATIC_BLOCK;
 
  /** Static Block **/
  static {
    if (System.currentTimeMillis() % 2 == 0) {
      STATIC_FINAL_INIT_STATIC_BLOCK = new HashSet<>();
    } else {
      STATIC_FINAL_INIT_STATIC_BLOCK = new LinkedHashSet<>();
    }
    STATIC_FINAL_INIT_STATIC_BLOCK.add(7);
    STATIC_FINAL_INIT_STATIC_BLOCK.add(21);
  }
}

package com.iderzheng.finalkeyword;
 
public class FinalFields {
 
  final long FINAL_INIT_INLINE = System.currentTimeMillis();
  final long FINAL_INIT_BLOCK;
  final long FINAL_INIT_CONSTRUCTOR;
 
  /** Initial Block **/
  {
    FINAL_INIT_BLOCK = System.nanoTime();
  }
 
  FinalFields() {
    this(217);
  }
 
  FinalFields(boolean bool) {
    FINAL_INIT_CONSTRUCTOR = 721;
  }
 
  FinalFields(long init) {
    FINAL_INIT_CONSTRUCTOR = init;
  }
}