#字符串转换为数字 #计算贷款月供和总额 #计算复利 #计算未来投资值

计算贷款支付额

月支付额 = 贷款总额月利率 /（1-1/（1+月利率）^(年数12））

import java.util.Scanner;
class Main {
  public static void main(String[] args) {
    //Create a Scanner
    Scanner input = new Scanner(System.in);

    //Enter yearly interest rate
    System.out.print("请输入年利率，比如 4.5：");
    double annualInterestRate = input.nextDouble();

    //Obtain monthly interest rate
    double monthlyInterestRate = annualInterestRate / 1200;

    //Enter number of years
    System.out.print("请输入年数，比如 5：");
    int numberOfYears = input.nextInt();
    
    //Enter loan amount
    System.out.print("请输入贷款总额，比如 300000：");
    double loanAmount = input.nextDouble();

    //Calculate payment
    double monthlyPayment = loanAmount * monthlyInterestRate / (1 - 1/Math.pow(1 +     monthlyInterestRate,numberOfYears * 12));
    double totalPayment = monthlyPayment * numberOfYears * 12;

    //Display results
    System.out.println("每月还款：" + (int)(monthlyPayment * 100) / 100.0);
    System.out.println("还款总额：" + (int)(totalPayment * 100) / 100.0);

    input.close();
  }
}

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字符串转换为数字

int intValue = Integer.parseInt(intString);
double doubleValue = Double.parseDouble(doubleString);

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使用输入对话框计算贷款支付额

import javax.swing.JOptionPane;
class Main {
  public static void main(String[] args) {
    //Enter yearly interest rate
    String annualInterestRateString = JOptionPane.showInputDialog("输入贷款年利率，比如4.85:");

    //Convert string to double
    double annualInterestRate = Double.parseDouble(annualInterestRateString);

    //Obtain monthly interest rate
    double monthlyInterestRate = annualInterestRate / 1200;

    //Enter numbe of years
    String numberOfYearsString = JOptionPane.showInputDialog("输入还款年数，比如30:");

    //Convert string to int
    int numberOfYears = Integer.parseInt(numberOfYearsString);

    //Enter loan amout
    String loadString = JOptionPane.showInputDialog("输入贷款总额，比如300000:");

    //Convert string to double
    double loanAmount = Double.parseDouble(loadString);

    //Calculate payment
    double monthlyPayment = loanAmount * monthlyInterestRate / (1 - 1 / Math.pow(1 + monthlyInterestRate, numberOfYears * 12));
    double totalPayment = monthlyPayment * numberOfYears * 12;

    //Format to keep two digits after the decimal point
    monthlyPayment = (int)(monthlyPayment * 100) / 100.0;
    totalPayment = (int)(totalPayment * 100) / 100.0;

    //Display results
    String output = "每月还款为：" + monthlyPayment + "\n总还款额为：" + totalPayment;
    JOptionPane.showMessageDialog(null,output);
 }
}

计算未来投资值

import javax.swing.JOptionPane;
import java.util.*;
class Main {
  public static void main(String[] args) {
    
		Scanner input = new Scanner(System.in);
		//
		System.out.println("Enter investment amount:");
		double investmentAmount = input.nextDouble();
		//
		System.out.println("Enter annually interest rate:");
		double annuallyInteresRate = input.nextDouble();
		double monthlyInterestRate = annuallyInteresRate / 1200;
		//
		System.out.println("Enter numer of years:");
		int numberOfYears = input.nextInt();
		
		double futureInvestmentValue = investmentAmount * 
			Math.pow((1 + monthlyInterestRate), numberOfYears * 12);
    futureInvestmentValue = (int)(futureInvestmentValue * 100) / 100.0;
    
		System.out.println("Accumuulated value is " +
						   futureInvestmentValue);


  }
}

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计算复利

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import java.util.*;
class Main {
  public static void main(String[] args) {
    Scanner input = new Scanner(System.in);
    System.out.println("请输入每月存款额：");
    double monthlySaveAmount = input.nextDouble();
    
    System.out.println("请输入年利率：");
    double annuallyInterestRate = input.nextDouble();
    double monthlyInterestRate = annuallyInterestRate / 1200;

    System.out.println("请输入存入月份：");
    int numbersOfMonth = input.nextInt();

    double amoutOfMoney = 0;
    for(int i = 0; i < numbersOfMonth; i++){
       amoutOfMoney = amoutOfMoney + monthlySaveAmount;
       amoutOfMoney = amoutOfMoney * (1 + monthlyInterestRate);
       amoutOfMoney = (int)(amoutOfMoney * 1000) / 1000.0;
       System.out.println("第" + i + "个月的帐面值为：" + amoutOfMoney);
    }
   input.close(); 
  }
}

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