Use of If/Else Statement in Java considering memory IO

I know this might be stupid question, but i am wondering when is the right time to use if/else statement.

Let's say we are constructing a heap by giving maximum heap size in primitive java int type. And this is my constructor.

public Heap(int maximumSize) {
        this.maximumSize = maximumSize;
        if (maximumSize < 1) {
            this.maximumSize = 100;
        }
        data = new int[this.maximumSize];
}

And i can write this also as

public Heap(int maximumSize) {
        if (maximumSize < 1) {
            this.maximumSize = 100;
        } else {
            this.maximumSize = maximumSize;
        }    
        data = new int[this.maximumSize];
}

I am wondering which is more efficient way considering all low level processes?