Question

How do I define a single constructor public packet(String[] biscuit) which makes my field from private String[] biscuitList to private String[] biscuit?

Answer 1

Just assign it to the field.

public class Packet {
    private String[] biscuitList;
    public Packet(String[] biscuit) {
        this.biscuitList = biscuit;
    }
}

The this refers to the current Packet instance (which you just created using new Packet). The this.biscuitList refers to the biscuitList field of the current Packet instance. The = biscuit assigns the given biscuit to the left hand (which in this case is the biscuitList field.

That said, a String[] variable shouldn’t really be called with a name ending in List. This may cause ambiguity with a List<String>. You can just call it biscuit, or maybe better, biscuits.

public class Packet {
    private String[] biscuits;
    public Packet(String[] biscuits) {
        this.biscuits= biscuits;
    }
}

Also, classnames and constructor names ought to start with uppercase. I.e. Packet and not packet.

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