If a boolean method is used inside an if condition, does it run before returning true?

I'm brand new to Java and I am working on an assignment that asks me to set-up a 'tower defense' game with insects. The game has tiles, where before you can create insects and place them on a tile, you have to check whether or not the insect 'fits'.

I'm struggling with setting up a constructor for a subclass Hornet of the abstract class Insect. Currently, every time the following code runs, two new Hornets are placed into the 'Swarm' array instead of one (Hornet objects are stored in an array called swarm).

public Insect(Tile position, int hp){
    this.position = position;
    this.hp = hp;
    if(position.addInsect(this)){
        position.addInsect(this);
    }
    else{
        throw new IllegalArgumentException("Insect does not fit on tile.");
    }

}

The 'addInsect' method checks whether or not the tile can fit the appropriate Insect that's being constructed on it, and if it can, it adds it and then returns true. So I thought I could place it as the condition for the if statement to check if it can add, and then if it can, it executes that method. But right now, this seems to be running twice. When I comment out the if statement and only have "position.addInsect(this)", then it seems to run properly and only make one Hornet.

Any help on what I'm doing wrong? Thank you!

Some more of my code in case:

The following is the 'addInsect' method:

    public boolean addInsect(Insect insectToAdd){
    if (insectToAdd instanceof HoneyBee) {
        if (this.beeOnTile == null && !this.hornetNestPresence) {
            this.beeOnTile = (HoneyBee) insectToAdd;
            insectToAdd.setPosition(this);
            return true;
        }
        else{
            return false;
        }
    }
    else if (insectToAdd instanceof Hornet){
        if (hornetNestPresence || beeHivePresence || this.isOnThePath()){
            if(this.swarmOnTile != null){
                this.swarmOnTile.addHornet((Hornet) insectToAdd);
                insectToAdd.setPosition(this);
                return true;}
            else{
                this.swarmOnTile = new SwarmOfHornets();
                this.swarmOnTile.addHornet((Hornet) insectToAdd);
                insectToAdd.setPosition(this);
                return true;
            }
        }
        else{
            return false;
        }
    }
    else{
        return false;
    }
}

And the following is the addHornet() method that is called when succesfully calling the addInsect method with a new Hornet:

    public void addHornet(Hornet newHornet){
    Hornet[] temp_swarm = new Hornet[this.sizeOfSwarm() + 1];

    for (int i = 0; i < this.sizeOfSwarm(); i++){
        temp_swarm[i] = swarm[i];
    }

    temp_swarm[this.sizeOfSwarm()] = newHornet;

    this.swarm = temp_swarm;
    this.swarm_size += 1;
}

Try to modify your constructor like this:

public Insect(Tile position, int hp) {
    this.position = position;
    this.hp = hp;
    
    if(!position.addInsect(this))
        throw new IllegalArgumentException("Insect does not fit on tile.");
}

I would suggest you to separate addInsect into 2 distinct methods, a checker (passive method) and an adder (active method):

public Insect(Tile position, int hp) {
this.position = position;
this.hp = hp;
if(position.canAddInsect(this))
position.addInsect(this);
else
throw new IllegalArgumentException("Insect does not fit on tile.");
}
public boolean canAddInsect(Insect insectToAdd) {
if (insectToAdd instanceof HoneyBee)
return (this.beeOnTile == null && !this.hornetNestPresence);
else if (insectToAdd instanceof Hornet)
return (hornetNestPresence || beeHivePresence || this.isOnThePath());
return false;
}
public void addInsect(Insect insectToAdd) {
if (insectToAdd instanceof HoneyBee) {
if (this.beeOnTile == null && !this.hornetNestPresence) {
this.beeOnTile = (HoneyBee) insectToAdd;
insectToAdd.setPosition(this);
}
} else if (insectToAdd instanceof Hornet) {
if (hornetNestPresence || beeHivePresence || this.isOnThePath()) {
if (this.swarmOnTile == null)
this.swarmOnTile = new SwarmOfHornets();
this.swarmOnTile.addHornet((Hornet) insectToAdd);
insectToAdd.setPosition(this);
}
}
}