银行借贷系统（Java编程）

package msg; import java.io.*; import java.util.*; class Mortgage extends Asset { // // Instance variables // private String mortgageeName; // names of mortgagees private float price; // price paid for mortgaged property private String dateMortgageIssued; // date mortgage was issued private float currentWeeklyIncome; // weekly income of mortgagees private String weeklyIncomeUpdated; // date weekly income updated private float annualPropertyTax; // annual property tax private float annualInsurancePremium; // annual insurance premium private float mortgageBalance; // mortgage balance static final int NUMBER_OF_MORTGAGE_PAYMENTS = 1560; static final float MAXIMUM_PERC_OF_INCOME = (float) 0.28; static final float WEEKS_IN_YEAR = (float) 52.0; static final float INTEREST_RATE = (float) 0.04; // getter-setter methods for Mortgage public String getMortgageeName () { return mortgageeName; } public void setMortgageeName (String n) { mortgageeName = n; } public float getPrice () { return price; } public void setPrice (float p) { price = p; } public String getDateMortgageIssued () { return dateMortgageIssued; } public void setDateMortgageIssued (String d) { dateMortgageIssued = d; } public float getCurrentWeeklyIncome () { return currentWeeklyIncome; } public void setCurrentWeeklyIncome (float c) { currentWeeklyIncome = c; } public String getWeeklyIncomeUpdated () { return weeklyIncomeUpdated; } public void setWeeklyIncomeUpdated (String w) { weeklyIncomeUpdated = w; } public float getAnnualPropertyTax () { return annualPropertyTax; } public void setAnnualPropertyTax (float p) { annualPropertyTax = p; } public float getAnnualInsurancePremium () { return annualInsurancePremium; } public void setAnnualInsurancePremium (float a) { annualInsurancePremium = a; } public float getMortgageBalance () { return mortgageBalance; } public void setMortgageBalance (float m) { mortgageBalance = m; } // // Instance methods // public float totalWeeklyNetPayments () // // Computes the net total weekly payments made by the mortgagees, that is, // the expected total weekly mortgage amount less the expected total weekly grants. // { try { File mortgageFile = new File ("mortgage.dat"); // file of mortgage records float expectedTotalWeeklyMortgages = (float) 0.0; // expected total weekly mortgages float expectedTotalWeeklyGrants = (float) 0.0; // expected total weekly grants float capitalRepayment = (float) 0.0; // capital repayment float interestPayment = (float) 0.0; // interest payment float escrowPayment = (float) 0.0; // escrow payment float tempMortgage = (float) 0.0; // temporary mortgage payment float maximumPermittedMortgagePayment = (float) 0.0; // maximum a family is allowed to pay if (mortgageFile.exists ()) { RandomAccessFile inFile = new RandomAccessFile (mortgageFile, "r"); while (inFile.getFilePointer () != inFile.length ()) { read (inFile); capitalRepayment = price / NUMBER_OF_MORTGAGE_PAYMENTS; interestPayment = mortgageBalance * INTEREST_RATE / WEEKS_IN_YEAR ; escrowPayment = (annualPropertyTax + annualInsurancePremium) / WEEKS_IN_YEAR; tempMortgage = capitalRepayment + interestPayment + escrowPayment; expectedTotalWeeklyMortgages += tempMortgage; maximumPermittedMortgagePayment = currentWeeklyIncome * MAXIMUM_PERC_OF_INCOME; if (tempMortgage > maximumPermittedMortgagePayment) expectedTotalWeeklyGrants += tempMortgage - maximumPermittedMortgagePayment; } inFile.close (); } // if return (expectedTotalWeeklyMortgages - expectedTotalWeeklyGrants); } catch (Exception e) { System.out.println ("***** Error: Mortgage.totalWeeklyNetPayments () *****"); System.out.println ("\t" + e); return ( (float) 0.0); } } // totalWeeklyNetPayments //---------------------------------------------------------------------------------------------------------------------------------------------------- public boolean find (String findMortgageID) // // find locates a given mortgage record if it exists. // Returns true if the mortgage is located, otherwise false. // { try { File mortgageFile = new File ("mortgage.dat"); // file of mortgage records boolean found = false; // result of comparison if (mortgageFile.exists ()) { RandomAccessFile inFile = new RandomAccessFile (mortgageFile, "r"); while (!found && (inFile.getFilePointer () != inFile.length ())) { read (inFile); if (assetNumber.compareTo (findMortgageID) == 0) found = true; } inFile.close (); } return found; } catch (Exception e) { System.out.println ("***** Error: Mortgage.find () *****"); System.out.println ("\t" + e); return false; } } // find //---------------------------------------------------------------------------------------------------------------------------------------------------- public void read (RandomAccessFile fileName) // // reads a mortgage record from fileName. // Assumes that the existence of fileName has already been established. // { try { String inputString = new String (); // for storing mortgage record int i = 0; // position within string inputString = fileName.readLine (); StringBuffer input = new StringBuffer (); while (inputString.charAt (i) != '|') { input.append (inputString.charAt (i)); i++; } assetNumber = input.toString (); i++; input = new StringBuffer (); while (inputString.charAt (i) != '|') { input.append (inputString.charAt (i)); i++; } mortgageeName = input.toString (); i++; input = new StringBuffer (); while (inputString.charAt (i) != '|') { input.append (inputString.charAt (i)); i++; } Float tempFloat = new Float (input.toString ()); price = tempFloat.floatValue (); i++; input = new StringBuffer (); while (inputString.charAt (i) != '|') { input.append (inputString.charAt (i)); i++; } dateMortgageIssued = input.toString (); i++; input = new StringBuffer (); while (inputString.charAt (i) != '|') { input.append (inputString.charAt (i)); i++; } tempFloat = new Float (input.toString ()); currentWeeklyIncome = tempFloat.floatValue (); i++; input = new StringBuffer (); while (inputString.charAt (i) != '|') { input.append (inputString.charAt (i)); i++; } weeklyIncomeUpdated = input.toString (); i++; input = new StringBuffer (); while (inputString.charAt (i) != '|') { input.append (inputString.charAt (i)); i++; } tempFloat = new Float (input.toString ()); annualPropertyTax = tempFloat.floatValue (); i++; input = new StringBuffer (); while (inputString.charAt (i) != '|') { input.append (inputString.charAt (i)); i++; } tempFloat = new Float (input.toString ()); annualInsurancePremium = tempFloat.floatValue (); i++; input = new StringBuffer (); while (i < inputString.length ()) { input.append (inputString.charAt (i)); i++; } tempFloat = new Float (input.toString ()); mortgageBalance = tempFloat.floatValue (); i++; } catch (Exception e) { System.out.println ("***** Error: Mortgage.read () *****"); System.out.println ("\t" + e); } } // read //---------------------------------------------------------------------------------------------------------------------------------------------------- public void write (RandomAccessFile fileName) // // writes a mortgage record to specified file. // { try { fileName.writeBytes (assetNumber + "|" + mortgageeName + "|"); fileName.writeBytes (price + "|" + dateMortgageIssued.toString () + "|"); fileName.writeBytes (currentWeeklyIncome + "|" + weeklyIncomeUpdated.toString () +