修改分数类和测试驱动程序JAVA

Question

我的教授创建了需要修改的代码。唯一的问题是，除了我自己是一个相当新的程序员之外，我根本不理解他的风格。分配的参数如下：
•修改setter，使其忽略不适当的值（即除以零）
•实现从顶级Object类继承的equals（）方法
•实施小于和大于的方法
•实现加法、减法和乘法方法

•确保equals方法对于算术相等的任何两个分数都返回true
•确保equals方法不会改变被比较分数的值
•lessThan和greaterThan方法必须分别返回一个布尔值，而不是字符串
•提供的reduce方法返回一个新的（reduced）分数对象作为其函数值

我对这项任务完全不知所措，因为我甚至不知道从哪里开始。任何帮助都将不胜感激！！！！我有一种感觉，一旦我看到它完成了，对我来说一切都会有意义。我只是根本不习惯这种教学风格。

public class Fraction {
        private int numer;
    	private int denom;
    
    	public Fraction() { // no-arg constructor
       		numer = 0;
        	denom = 1;
	}
    
    	public Fraction(int numer, int denom) {
                this.numer = numer;
        	this.denom = denom;
        }
    	public Fraction(Fraction frac) { // copy constructor
        	numer = frac.getNumer();
        	denom = frac.getDenom();
    	}
     	// getters and setters
    	public int getNumer() {
        	return numer;
    	}
    
    	public void setNumer(int x) {
        	numer = x;
    	}
    
        public int getDenom()  {
        	return denom;
    	}
    
    	public void setDenom(int x) {
            denom = x;
    	}
   
 	// Special Methods
    	public String toString() {
        	return numer + "/" + denom;
    	}
    	// Other Methods
    	public Fraction reduce() {
        	Fraction temp = new Fraction();
        
        	int GCD = gcd(numer, denom);
        
        	temp.setNumer(numer / GCD);
        	temp.setDenom(denom / GCD);
        
        	return  temp;
    	}
 	
	 // Private Methods
    	private int gcd(int n1, int n2)
    	{
        	int M, N, R;
        
        	if (n1 < n2)
        	{
            		N = n1;
            		M = n2;
        	}
        	else
        	{
            		N = n2;
           	 	M = n1;
        	}
        
        	R = M % N;
        
        	while (R != 0)
        	{
            		M = N;
            		N = R;
            
            		R = M % N;
        	}
        
        	return N;
        
        }
 
    public static void main(String[] args) {
    // test constructors
        	Fraction frac0 = new Fraction();
        	System.out.println("TESTING NO-ARG CONSTRUCTOR");
		System.out.println("frac0: Result should be 0/1:");
        	System.out.println("Numer = " + frac0.getNumer());
        	System.out.println("Denom = " + frac0.getDenom());
        
        	System.out.println("TESTING int/int CONSTRUCTOR");
        	Fraction frac1 = new Fraction(2,4);
		System.out.println("frac1: Result should be 2/4:");
        	System.out.println("Numer = " + frac1.getNumer());
        	System.out.println("Denom = " + frac1.getDenom());
        
        	System.out.println("TESTING Fraction CONSTRUCTOR");
        	Fraction frac2 = new Fraction(frac1);
		System.out.println("frac2: Result should be 2/4:");
        	System.out.println("Numer = " + frac2.getNumer());
        	System.out.println("Denom = " + frac2.getDenom());
		System.out.println("TESTING COPY CONSTRUCTOR frac1  frac2");
        	if (frac1.getNumer() == frac2.getNumer() &&
            		frac1.getDenom() == frac2.getDenom() &&
              		frac1 != frac2)
        	{
            		System.out.println("Copy constructor working");
        	}
        	else
            		System.out.println("PROBLEM with copy constructor");
        
        	// test equal method
        	System.out.println("TESTING EQUALITY OF frac1 and frac2 -");
		System.out.println("SHOULD BE FOUND EQUAL:");
		if (frac1.equals(frac2))
        	{
            		System.out.println("frac1 and frac2 found equal");
        	}
        	else
        	{
            		System.out.println("frac1 and frac2 NOT equal");
        	}
            	// test reduce method
        	System.out.println("TESTING reduce METHOD ON frac1");
		Fraction reduced_frac1 = frac1.reduce();
        	System.out.println("Reduced frac1 = " + reduced_frac1);
        
        	// test getters and setters
        	frac2.setNumer(8);
        	frac2.setDenom(12);
        	System.out.println("Numer = " + frac2.getNumer());
        	System.out.println("Denom = " + frac2.getDenom());
        
        	// System.out.println("GCD of 2/4 = " + frac1.gcd(1,4));
       
    	}
	//* TO BE COMPLETED *
}

Answer 1

他的教学方法没有错，经过进一步的学习，我相信你会弄清楚的。这里没有人会帮你做，我也不想做你的家庭作业，所以我会问一个常见的问题，到目前为止你试过什么？我给了你一个改良的二传手。继续工作，更好地学习你的java，否则当它变得困难时，你会遇到困难。

//Here is where you start
public void setDenom(int x){
    if(x > 0){
       denom = x;
    }else{
       //throw an error
    }
}