How to use

hasOpponent

method

in

mage.players.Player

public int getAllOppLifeLost(UUID playerId, Game game) {
  int amount = 0;
  for (UUID opponentId : this.amountOfLifeLostThisTurn.keySet()) {
    Player opponent = game.getPlayer(opponentId);
    if (opponent != null && opponent.hasOpponent(playerId, game)) {
      amount += this.amountOfLifeLostThisTurn.getOrDefault(opponentId, 0);
    }
  }
  return amount;
}

public int getAllOppLifeLost(UUID playerId, Game game) {
  int amount = 0;
  for (UUID opponentId : this.amountOfLifeLostThisTurn.keySet()) {
    Player opponent = game.getPlayer(opponentId);
    if (opponent != null && opponent.hasOpponent(playerId, game)) {
      amount += this.amountOfLifeLostThisTurn.getOrDefault(opponentId, 0);
    }
  }
  return amount;
}

@Override
public boolean applies(GameEvent event, Ability source, Game game) {
  Player player = game.getPlayer(source.getControllerId());
  if (player == null) {
    return false;
  }
  return player.hasOpponent(event.getTargetId(), game)
      || player.hasOpponent(game.getControllerId(event.getTargetId()), game);
}

@Override
public boolean applies(GameEvent event, Ability source, Game game) {
  Player controller = game.getPlayer(source.getControllerId());
  return controller != null && controller.hasOpponent(event.getPlayerId(), game);
}

@Override
public boolean applies(GameEvent event, Ability source, Game game) {
  Player controller = game.getPlayer(source.getControllerId());
  if (controller != null) {
    return controller.hasOpponent(event.getPlayerId(), game);
  }
  return false;
}

@Override
public boolean applies(Permanent permanent, Ability source, Game game) {
  Player controller = game.getPlayer(source.getControllerId());
  return controller != null && controller.hasOpponent(game.getActivePlayerId(), game);
}

@Override
public void watch(GameEvent event, Game game) {
  if (condition) { //no need to check - condition has already occured
    return;
  }
  if (event.getType() == GameEvent.EventType.DAMAGED_PLAYER) {
    DamagedPlayerEvent damageEvent = (DamagedPlayerEvent) event;
    if (game.getPlayer(this.getControllerId()).hasOpponent(damageEvent.getPlayerId(), game)) {
      condition = true;
    }
  }
}

@Override
public boolean applies(GameEvent event, Ability source, Game game) {
  if (event.getType() == GameEvent.EventType.CREATE_TOKEN) {
    Player controller = game.getPlayer(source.getControllerId());
    if (controller != null && controller.hasOpponent(event.getPlayerId(), game)) {
      return true;
    }
  }
  return false;
}

  @Override
  public boolean applies(GameEvent event, Ability source, Game game) {
    if (event.getAmount() > 1) {
      Player controller = game.getPlayer(source.getControllerId());
      if (controller != null && controller.hasOpponent(event.getPlayerId(), game)) {
        return true;
      }
    }
    return false;
  }
}

  @Override
  public boolean canBlock(Permanent attacker, Permanent blocker, Ability source, Game game) {
    for (UUID creature : game.getCombat().getBlockers()) {
      if (game.getPlayer(game.getPermanent(creature).getOwnerId()).hasOpponent(attacker.getControllerId(), game)) {
        return false;
      }
    }
    return true;
  }
}

@Override
public boolean checkTrigger(GameEvent event, Game game) {
  if (event.getFlag()) {
    return false;
  }
  Permanent permanent = game.getPermanent(event.getTargetId());
  Player player = game.getPlayer(controllerId);
  return permanent != null && player != null && permanent.isCreature()
      && player.hasOpponent(permanent.getControllerId(), game);
}

  @Override
  public boolean applies(GameEvent event, Ability source, Game game) {
    Player controller = game.getPlayer(source.getControllerId());
    if (controller != null && controller.hasOpponent(event.getPlayerId(), game)) {
      Card card = game.getCard(event.getSourceId());
      if (card != null && !card.isCreature()) {
        return true;
      }
    }
    return false;
  }
}

@Override
public boolean checkTrigger(GameEvent event, Game game) {
  ZoneChangeEvent zEvent = (ZoneChangeEvent) event;
  if (zEvent.getToZone() == Zone.GRAVEYARD && zEvent.getFromZone() == Zone.BATTLEFIELD) {
    Card card = game.getCard(zEvent.getTargetId());
    Player controller = game.getPlayer(getControllerId());
    return card != null && controller != null && controller.hasOpponent(card.getOwnerId(), game);
  }
  return false;
}

@Override
public boolean checkTrigger(GameEvent event, Game game) {
  if (((ZoneChangeEvent)event).isDiesEvent()) {
    Card card = game.getPermanentOrLKIBattlefield(event.getTargetId());
    Player controller = game.getPlayer(getControllerId());
    if (controller != null && card != null && card.isArtifact()
        && controller.hasOpponent(card.getOwnerId(), game)) {
      return true;
    }
  }
  return false;
}

@Override
public boolean apply(Game game, Ability source) {
  Player activePlayer = game.getPlayer(game.getActivePlayerId());
  return activePlayer != null && activePlayer.hasOpponent(source.getControllerId(), game) && game.getPhase().getStep().getType().getIndex() < 5;
}

@Override
public boolean apply(Game game, Ability source) {
  Player activePlayer = game.getPlayer(game.getActivePlayerId());
  return activePlayer != null && activePlayer.hasOpponent(source.getControllerId(), game) && game.getPhase().getStep().getType().getIndex() < 5;
}

@Override
public boolean checkTrigger(GameEvent event, Game game) {
  if (game.getPlayer(this.getControllerId()).hasOpponent(event.getPlayerId(), game)) {
    if (setTargetPointer) {
      for (Effect effect:this.getEffects()) {
        effect.setTargetPointer(new FixedTarget(event.getPlayerId()));
      }
    }
    return true;
  }
  return false;
}

@Override
public boolean checkTrigger(GameEvent event, Game game) {
  Permanent permanent = game.getPermanentOrLKIBattlefield(event.getTargetId());
  Player targetter = game.getPlayer(event.getPlayerId());
  if (permanent != null && permanent.isControlledBy(this.getControllerId()) && permanent.isCreature()) {
    Object object = game.getObject(event.getSourceId());
    if (object != null && targetter != null && targetter.hasOpponent(this.getControllerId(), game)) {
      return true;
    }
  }
  return false;
}

  @Override
  public boolean applies(GameEvent event, Ability ability, Game game) {
    MageObject mageObject = game.getObject(event.getSourceId());
    if (game.getPlayer(ability.getControllerId()).hasOpponent(event.getPlayerId(), game) &&
        mageObject instanceof Spell &&
        (mageObject.getColor(game).isBlack() || mageObject.getColor(game).isBlue())) {
      Permanent permanent = game.getPermanent(event.getTargetId());
      return permanent != null && permanent.isControlledBy(ability.getControllerId());
    }
    return false;
  }
}

@Override
public boolean applies(GameEvent event, Ability source, Game game) {
  if (game.getPlayer(source.getControllerId()).hasOpponent(event.getPlayerId(), game)) {
    FilterCard filter = new FilterCard();
    filter.add(Predicates.not(new CardTypePredicate(CardType.CREATURE)));
    filter.add(new ConvertedManaCostPredicate(ComparisonType.MORE_THAN, getLandCount(source, event, game)));
    Card card = game.getCard(event.getSourceId());
    return card != null && filter.match(card, game);
  }
  return false;
}