Fractionという名前の新しいクラスを作成する

Question

私のプログラムは、3つのコンストラクタと4つのメソッドを持つ新しい分数を作成できるようになっています。しかし、テストドライバを使ってプログラムを実行すると、ドライバのコンパイルが正しく行われません。私がコンストラクタをテストすると、デフォルトのコンストラクタが0/1になりたいのではなく、y/zが返されます。私の分数の大半は整数として出てくるわけではありませんが、まだ私が割り当てた変数は です。これはどうしてですか？相続人

public class Fraction //new class name 

     { 
//class data 
private int numerator; 
private int denominator; 
private int y; 
private int z; 


//constructors 
public Fraction()   // default - sets numerator to 0/denominator to 1. 
{ 
    this.numerator = 0; 
    this.denominator = 1; 
} 

public Fraction (Fraction y) //PARAMETERIZED - numerator takes input Y, denominator is 1. 
{ 
    this.numerator = y; 
    this.denominator = 1; 
} 

public Fraction (int y, int z) //parametrized - throws new illegalarumentexception 
{ 
    this.numerator = y; 
    this.denominator = z; 
    if (z == 0) 
     throw new IllegalArgumentException(z+ " cannot equal 0."); 
} 


//methods 
public String toString() //should return fraction in a string 
{ 
    return ("y/z"); 
} 

public double evaluate() //returns fraction as a decimal in double 
{ 
    return (double) y/z; 
} 

public boolean isImproper() 
{ 
    return y > z; 
} 

public Fraction multiply (Fraction another) 
{ 
    return new Fraction (this.numerator*another.numerator); 
} 

}

ドライバ：

 **public class FractionTester 
    { 
public static void main(String[] args) 
{ 
    //create and test Fractions 
    System.out.println("------ Part1: Testing Fractions's constructors and toString()"); 

    System.out.println("\nTest1.1: Testing default constructor, then toString()"); 
    try 
    { 
     System.out.print("expected: 0/1 \ngot:  "); 
     Fraction f1 = new Fraction(); 
     System.out.println(f1); 
    } 
    catch (Throwable ex) 
    { 
     System.out.println("got:  " + ex); 
    } 

    System.out.println("\nTest1.2: Testing new Fraction(2) constructor, then toString()"); 
    try 
    { 
     System.out.print("expected: 2/1 \ngot:  "); 
     Fraction f1 = new Fraction(2); 
     System.out.println(f1); 
    } 
    catch (Throwable ex) 
    { 
     System.out.println("got:  " + ex); 
    } 


    System.out.println("\nTest1.3: Testing new Fraction(2, 5) constructor, then toString()"); 
    try 
    { 
     System.out.print("expected: 2/5 \ngot:  "); 
     Fraction f1 = new Fraction(2, 5); 
     System.out.println(f1); 
    } 
    catch (Throwable ex) 
    { 
     System.out.println("got:  " + ex); 
    } 

    System.out.println("\nTest1.4: Testing new Fraction(2, 0) constructor (bad input), then toString()"); 
    try 
    { 
     System.out.print("expected: java.lang.IllegalArgumentException(<your descriptive String>) \ngot:  "); 
     Fraction f1 = new Fraction(2, 0); 
     System.out.println(" no exception"); 
    } 
    catch (Throwable ex) 
    { 
     System.out.println(ex); 
    } 

    System.out.println("\nTest1.5: Testing new Fraction(0, 2) constructor (OK), then toString()"); 
    try 
    { 
     System.out.print("expected: 0/2 \ngot:  "); 
     Fraction f1 = new Fraction(0, 2); 
     System.out.println(f1); 
    } 
    catch (Throwable ex) 
    { 
     System.out.println("got:  " + ex); 
    } 


    System.out.println("\n------ Part2: Testing Fraction's methods"); 

    System.out.println("\nTest2.1: Testing .evaluate with 3/4 (original should be unchanged)"); 
    try 
    { 
     System.out.print("expected: 0.75 \ngot:  "); 
     Fraction f1 = new Fraction(3,4); 
     String originalToString = f1.toString(); 
     double result = f1.evaluate(); 
     System.out.println(result); 

     if (!originalToString.equals(f1.toString())) 
      System.out.println("***** BUT THE ORIGINAL FRACTION CHANGED"); 
    } 
    catch (Throwable ex) 
    { 
     System.out.println("got:  " + ex); 
    } 

    System.out.println("\nTest2.2: Testing .isImproper with 7/6 (original should be unchanged)"); 
    try 
    { 
     System.out.print("expected: true \ngot:  "); 
     Fraction f1 = new Fraction(7,6); 
     String originalToString = f1.toString(); 
     boolean result = f1.isImproper(); 
     System.out.println(result); 

     if (!originalToString.equals(f1.toString())) 
      System.out.println("***** BUT THE ORIGINAL FRACTION CHANGED"); 
    } 
    catch (Throwable ex) 
    { 
     System.out.println("got:  " + ex); 
    } 

    System.out.println("\nTest2.3: Testing .isImproper with 10/13 (original should be unchanged)"); 
    try 
    { 
     System.out.print("expected: false \ngot:  "); 
     Fraction f1 = new Fraction(10,13); 
     String originalToString = f1.toString(); 
     boolean result = f1.isImproper(); 
     System.out.println(result); 

     if (!originalToString.equals(f1.toString())) 
      System.out.println("***** BUT THE ORIGINAL FRACTION CHANGED"); 
    } 
    catch (Throwable ex) 
    { 
     System.out.println("got:  " + ex); 
    } 

    System.out.println("\nTest2.4: Testing .isImproper with 7/7 (original should be unchanged)"); 
    try 
    { 
     System.out.print("expected: false \ngot:  "); 
     Fraction f1 = new Fraction(7,7); 
     String originalToString = f1.toString(); 
     boolean result = f1.isImproper(); 
     System.out.println(result); 

     if (!originalToString.equals(f1.toString())) 
      System.out.println("***** BUT THE ORIGINAL FRACTION CHANGED"); 
    } 
    catch (Throwable ex) 
    { 
     System.out.println("got:  " + ex); 
    } 

    System.out.println("\nTest2.5: Testing .multiply 4/5 times 3/11 (original should be unchanged)"); 
    try 
    { 
     System.out.print("expected: 12/55 \ngot:  "); 
     Fraction f1 = new Fraction(4, 5); 
     String originalf1ToString = f1.toString(); 
     Fraction f2 = new Fraction(3, 11); 
     String originalf2ToString = f2.toString(); 

     Fraction f3 = f1.multiply(f2); 
     System.out.println(f3); 

     if (!originalf1ToString.equals(f1.toString()) || !originalf2ToString.equals(f2.toString())) 
      System.out.println("***** BUT THE ORIGINAL FRACTION(S) WERE CHANGED!"); 
    } 
    catch (Throwable ex) 
    { 
     System.out.println("got:  " + ex); 
    } 

} //end of main 
    } //end of class** 

Answer 1

あなたtoString()メソッドは常にy/zを出力します。