某个变量被赋值超过一次，它既不是循环变量，也不被用于汇总结果

double temp = 2 * (height + width);
System.out.println(temp);
temp = height * width;
System.out.println(temp);

重构后

final double perimeter = 2 * (height + width);
System.out.println(perimeter);
final double area = height * width;
System.out.println(area);