Still struggling with constructors

[Troy Johnson]

Hello. I still seem to be struggling a bit getting this to work properly. I have made some modifications based upon previous suggestions and responses. I am tyring to modify the code by adding two additional constructors, one that takes the "annual interest rate" and "loan amount", and one that takes just the "loan amount". I need to use the keyword "this" to invoke new constructor. I am also to write a test program to test all constructors. Here is my original code and the modifications I have made. Please let me know if anyone has any suggestions or can help. Sorry, for the repetitive posts. I am new to Java. Thanks.

Here is my original code:

// Mortgage.java: Encapsulate mortgage information
public class Mortgage {
  private double annualInterestRate;
  private int numOfYears;
  private double loanAmount;
  /** Default constructor */
  public Mortgage() {
    this(7.5, 30, 100000);
  }
  /** Construct a mortgage with specified annual interest rate,
      number of years and loan amount
    */
  public Mortgage(double annualInterestRate, int numOfYears,
    double loanAmount) {
    this.annualInterestRate = annualInterestRate;
    this.numOfYears = numOfYears;
    this.loanAmount = loanAmount;
  }
  /** Return annualInterestRate */
  public double getAnnualInterestRate() {
    return annualInterestRate;
  }
  /** Set a new annualInterestRate */
  public void setAnnualInterestRate(double annualInterestRate) {
    this.annualInterestRate = annualInterestRate;
  }
  /** Return numOfYears */
  public int getNumOfYears() {
    return numOfYears;
  }
  /** Set a new numOfYears */
  public void setNumOfYears(int numOfYears) {
    this.numOfYears = numOfYears;
  }
  /** Return loanAmount */
  public double getLoanAmount() {
    return loanAmount;
  }
  /** Set a newloanAmount */
  public void setLoanAmount(double loanAmount) {
    this.loanAmount = loanAmount;
  }
  /** Find monthly payment */
  public double monthlyPayment() {
    double monthlyInterestRate = annualInterestRate / 1200;
    return loanAmount * monthlyInterestRate / (1 - 
      (Math.pow(1 / (1 + monthlyInterestRate), numOfYears * 12)));
  }
  /** Find total payment */
  public double totalPayment() {
    return monthlyPayment() * numOfYears * 12;
  }
}

Here is the modification and solution I have so far

// Mortgage.java: Encapsulate mortgage information

public class Mortgage1
{
   public static void main(String[] args){new Mortgage();} {
Mortgage1 Mortgage = new Mortgage1();
Mortgage a = new Mortgage(7.5,30,100000);
Mortgage b = new Mortgage(7,50000);
Mortgage c = new Mortgage(100000);
System.out.println(a.toString());
    System.out.println(b.toString());
    System.out.println(c.toString());

    }
}
 class Mortgage {
  private double annualInterestRate = 7.5 ;
  private int numOfYears = 30;
  private double loanAmount =100000;
  /** Default constructor */
  public Mortgage {
    this(7.5, 30, 100000);
}
/*Modify with new constructors*/
   public Mortgage {
   this(30,annualInterestRate,loanAmount);
   this(7.5,30,loanAmount);
  }
//** Construct annual interest rate and loan amount*/

     public Mortgage(double annualInterestRate, double loanAmount) {
 this.annualInterestRate = annualInterestRate;
     this.loanAmount = loanAmount;
 }
 /** Return annualInterestRate and loan Amount
     */
     public double getAnualInterestRate(){
 public double getloanAmount() {
 return annualInterestRate * loanAmount;
     return loanAmount;

 }
 /** Return loan amount only*/
     public double getloanAmount(){
 return loanAmount;

}
  /** Construct a mortgage with specified annual interest rate,
      number of years and loan amount
    */
  public Mortgage(double annualInterestRate, int numOfYears,
    double loanAmount) {
    this.annualInterestRate = annualInterestRate;
    this.numOfYears = numOfYears;
    this.loanAmount = loanAmount;
  }
  /** Return annualInterestRate */
  public double getAnnualInterestRate() {
    return annualInterestRate;
  }
  /** Set a new annualInterestRate */
  public void setAnnualInterestRate(double annualInterestRate) {
    this.annualInterestRate = annualInterestRate;
  }
  /** Return numOfYears */
  public int getNumOfYears() {
    return numOfYears;
  }
  /** Set a new numOfYears */
  public void setNumOfYears(int numOfYears) {
    this.numOfYears = numOfYears;
  }
  /** Return loanAmount */
  public double getLoanAmount() {
    return loanAmount;
  }
  /** Set a newloanAmount */
  public void setLoanAmount(double loanAmount) {
    this.loanAmount = loanAmount;
  }
  /** Find monthly payment */
  public double monthlyPayment() {
    double monthlyInterestRate = annualInterestRate / 1200;
    return loanAmount * monthlyInterestRate / (1 -
      (Math.pow(1 / (1 + monthlyInterestRate), numOfYears * 12)));
  }
  /** Find total payment */
  public double totalPayment() {
    return monthlyPayment() * numOfYears * 12;
}
  public String toString() {
      return "loanAmount " + loanAmount  + "\n"
        + "anualInterestRate " + annualInterestRate + "\n"
        + "numYears" + numYears + "\n"
  }
}

[ October 22, 2003: Message edited by: Troy Johnson ]

[Ernest Friedman-Hill]

To call one constructor from another, you use "this()". In the parentheses, you put the arguments to pass to the other constructor. For example

public Foo(int x, int y, int z) {
  // Do something with x, y, and z
}
public Foo(int x, int y) {
  // "z" defaults to zero
  this(x, y, 0);
}

Is that enough information?

[Michael Dunn]

I *think* I can see what you're trying to do now

class Mortgage
{
  private double annualInterestRate;
  private int numOfYears;
  private double loanAmount;
  
  public Mortgage()
  {
    this(7.5,30,100000);
  }                                     
  public Mortgage(double amount)
  {
    this(7.5,30,amount);
  }                 
  public Mortgage(double rate, double amount)
  {
    this(rate,30,amount);
  }                                            
  public Mortgage(double rate, int years, double amount)
  {
    annualInterestRate = rate;
    numOfYears = years;
    loanAmount = amount;
  }                               

(rest of code snipped)

[Ernest Friedman-Hill]

I *think* I can see what you're trying to do now

Well, indeed. We all could see that. I would hoping to give him enough information to work this out for himself. He won't learn anything at all from cutting and pasting your code into his assignment!

[Michael Dunn]

Ernest, my post was more of a correction to my post in his other thread.
As for him learning Vs not learning, that's for him to choose, not me.

[Troy Johnson]

Thanks everyone for all of your help. I greatly appreciate it. I think I finally got it figured out now. Thanks again.

[Ernest Friedman-Hill]

Michael --
Sorry for the rebuke. I was annoyed with someone else and I took it out on you.

[Michael Dunn]

Ernest, not a problem, and while I'm here, I would like to say thanks for a whole bunch of your code snippets that have turned many of my Java 'doubtful' areas into 'hey, light bulb's now on'.
Thanks again.