Final answer:
The method 'makeSquare' takes a Rectangle object as an argument and sets its width to match its length, thus converting it into a square.
Step-by-step explanation:
The question asks for a method in Java that takes a Rectangle object as a parameter and modifies it so that its width becomes equal to its length, effectively turning it into a square. Here's a concise method that accomplishes this:
public void makeSquare(Rectangle rect) {
rect.width = rect.length;
}
Assuming that you have a class named Rectangle with the properties width and length, this method sets the width of the rectangle to its length, thereby transforming the rectangle into a square. Note that this method assumes that the Rectangle class has public or accessible fields or utilizes appropriate setters to modify its dimensions.