貸款支付方程

Question

我想爲任何類型的固定利率分期貸款（包括抵押貸款）做一個計算器。這是我的一個基本的計算器的以下腳本：

EditText myEdit = (EditText) findViewById(R.id.editBalance); 
      String myEditValue = myEdit.getText().toString(); 
      double loanAmount = Double.parseDouble(myEditValue); 

      EditText myEdit2 = (EditText) findViewById(R.id.editRate); 
      String myEditValue2 = myEdit2.getText().toString(); 
      double interestRate = Double.parseDouble(myEditValue2); 

      EditText myEdit3 = (EditText) findViewById(R.id.editTerm); 
      String myEditValue3 = myEdit3.getText().toString(); 
      Double loanPeriod = Double.parseDouble(myEditValue3); 

      double r = interestRate/1200; 
      double r1 = Math.pow(r+1,loanPeriod); 

      double editMnthlypmt = (double) ((r+(r/(r1-1))) * loanAmount); 

      TextView textMnthlypmt = (TextView)findViewById(R.id.textMntlypmt); 
      textMnthlypmt.setText("" + String.valueOf(editMnthlypmt)); 

我想添加一個textEdit進行額外的每月付款;然而，我不知道如何計算這個值，或者調整我的公式editMnthlypmt。

有什麼建議嗎？

Answer 1

該方程已完成，運作非常好。

 case R.id.calculate2: 

     if (nicknameStr.length() > 0 && origBalStr.length() > 0 && myAPRStr.length() > 0 && origTermStr.length() > 0 && myPmtStr.length() > 0) 
     {    

      double originalBalance = Double.parseDouble(origBalStr); 
      double interestRate = Double.parseDouble(myAPRStr); 
      double originalTerm = Double.parseDouble(origTermStr); 
      double remainingBalance = Double.parseDouble(strOutBal); 

      double r = interestRate/1200; 
      double r1 = Math.pow(r+1,originalTerm); 

      double minPmt = (double) ((r+(r/(r1-1))) * originalBalance); 
      DecimalFormat df = new DecimalFormat("#.##");  
      minPmt = Double.valueOf(df.format(minPmt)); 

      dispMinPmt.setText("" + String.valueOf(minPmt)); 


      double additionalPayment = Double.parseDouble(myPmtStr); 
      double newPmt = minPmt + additionalPayment; 

      dispNewPmt.setText("" + newPmt); 

      double periodRate = r; 

      double remTop = ((-1*Math.log(1-(periodRate) * (remainingBalance/newPmt)))); 
      double remBottom = (Math.log(1 + periodRate)); 
      double nRemaining = remTop/remBottom; 

      double initialInt = (minPmt * nRemaining) - remainingBalance; 
      double newInt = (newPmt * nRemaining) - remainingBalance; 
      double amountSaved = initialInt - newInt; 

     } 
     else 
     { 
      Toast.makeText(getApplicationContext(), "Please complete all above fields", Toast.LENGTH_SHORT).show(); 
     } 

     break;