java语言程序设计（基础篇） 第2章 基本程序设计 课本源代码

//程序清单2-1
public class ComputeArea {
	//功能:实现计算圆面积
	
	public static void main(String[] args) {
		
		double radius;	//Declare radius
		double area;	//Declare area
		
		//Assign a radius
		radius = 20;
		
		//Compute Area
		area = radius * radius * 3.14159;
		
		//Display results
		System.out.println("The area for the circle of radius "+
				radius + " is " + area);

	}

}

//程序清单2-2
import java.util.Scanner;
//功能：从标准输入设备读取Double类型数，实现计算圆面积
public class ComputeAreaWithConsuleInput {

	public static void main(String[] args) {
	
		//Create a Scanner object
		Scanner input = new Scanner(System.in);
		
		//Prompt the user to enter a radius
		System.out.print("Enter a number for radius: ");
		double radius = input.nextDouble();
		
		//Compute area
		double area = radius * radius * 3.14159;
		
		//Display result
		System.out.println("The area for the circle of radius "+
				radius + "is " +area);

	}

}


//程序清单2-3
//功能：读取三个数值，然后显示它们的平均值

import java.util.Scanner;

public class ComputeAverage {

	public static void main(String[] args) {
		//Create a Scanner object
	   Scanner input = new Scanner(System.in);
	   
	   //Prompt the user to enter three numbers
	   System.out.print("Enter three numbers: ");
	   double number1 = input.nextDouble();
	   double number2 = input.nextDouble();
	   double number3 = input.nextDouble();
	   
	   //Compute average
	   double average = (number1 + number2 + number3)/3;
	   
	   //Display result
	   System.out.println("The average of "+ number1  + ""
			   +  number2  + "" +  number3  + " is " + average);	

	}

}


//程序清单2-4 
//功能：计算一个以秒为单位的时间量所包含的分钟数和剩余秒数的程序
import java.util.Scanner;

public class DisplayTime {
	
	public static void main(String[] args) {
		Scanner input = new Scanner(System.in);
		//提示用户输入
		System.out.println("Enter an integer for seconds: ");
		int seconds = input.nextInt();
		
		int minutes = seconds / 60; //计算包含的分钟数
		int remainingSeconds = seconds % 60; //剩余秒数
		System.out.println(seconds + " seconds is " + minutes +
				" minutes and "+ remainingSeconds + " seconds");
	}

}


//程序清单2-5
//功能：利用公式将华氏温度转换成摄氏温度
import java.util.Scanner;
public class FahrenheitToCelsius {
	public static void main(String[] args) {
		Scanner input = new Scanner(System.in);
		
		System.out.print("Enter a degree in Fahrenheit: ");
		double fahrenheit = input.nextDouble();
		
		//Convert Fahrenheit to Celsius
		double celsius = (5.0 / 9) * (fahrenheit - 32);
		System.out.println("Fahrenheit " + fahrenheit + " is "
				+ celsius + "in Celsius");

	}

}


//程序清单2-6 ShouCurrentTime.java
//功能：显示当前时间
//说明：本题是开发一个显示当前GMT(格林威治标准时间）的程序；
public class ShowCurrentTime {

	public static void main(String[] args) {
		//获得从1970年1月1日0点到当前时间之间单位为毫秒的差值
		long totalMilliseconds = System.currentTimeMillis();
		
		//获取总的秒数
		long totalSeconds = totalMilliseconds / 1000;
		
	   //计算当前秒数
		long currentSecond = totalSeconds % 60;
		
		//获取总分钟数
		long totalMinutes = totalSeconds / 60;
		
		//计算当前分钟数
		long currentMinute = totalMinutes % 60;
		
		//获取总的小时数
		long totalHours = totalMinutes / 60;
		
		//计算当前小时数
		long currentHour = totalHours % 60;
		
		//输出结果
		System.out.println("Current time is " + currentHour + ":"
				+ currentMinute + ":" + currentSecond + "GMT");
	}

}


//程序清单2-8 ComputeLoan.java
import java.util.Scanner;

public class ComputeLoan {

	public static void main(String[] args) {
		//创建一个Scanner对象
		Scanner input = new Scanner(System.in);
		
		//输入年利率
		System.out.println("Enter yearly interest rate,for example 8.25:" );
		double annualInterestRate = input.nextDouble();
		
		//获取月利率
		double monthlyInterestRate = annualInterestRate/1200;
		
		//输入年数
		System.out.println(
				"Enter number of years as an integer,for example 5: ");
		int numberOfYears = input.nextInt();
		
		//输入贷款总数
		System.out.println("Enter loan amount,for example 120000.95: ");
		double loanAmount = input.nextDouble();
		
		//计算每月贷款支付额和总贷款支付额
		double monthlyPayment = loanAmount * monthlyInterestRate / (1 
				- 1 / Math.pow(1+monthlyInterestRate,numberOfYears*12));
		double totalPayment = monthlyPayment * numberOfYears * 12;
		
		//输出计算结果
		System.out.println("The monthly payment is " + (int)(monthlyPayment * 100)/100.0);
		System.out.println("The total payment is " + (int)(totalPayment * 100)/100.0);
		

	}

}


//程序清单2-9 DisplayUnicode.java
//程序功能：显示两个中文字符和三个希腊字母
import javax.swing.JOptionPane;

public class DisplayUnicode {
	public static void main(String[] args){
		JOptionPane.showMessageDialog(null, "\u6B22\u8FCE \u03b1\u03b2\u03b3",
				"\u6B22\u8FCE welcome",JOptionPane.INFORMATION_MESSAGE);

	}

}


//程序清单2-10
//程序功能：整钱兑零
import java.util.Scanner;

public class ComputeChange {
	public static void main(String[] args){
		//创建一个Scanner
		Scanner input = new Scanner(System.in);
		
		//从控制台输入钱数
		System.out.print(
				"Enter an amount in double, for example 11.56: ");
		double amount = input.nextDouble();
		
		//引入变量remainingAmount来存储变化的余额
		int remainingAmount = (int)(amount * 100); //将钱数转换为1分币的个数
		
		//求出1美元的个数
		int numberOfOneDollars = remainingAmount / 100;
		remainingAmount = remainingAmount % 100;
		
		//求出2角5分币的个数
		int numberOfQuarters = remainingAmount / 25;
		remainingAmount = remainingAmount % 25; 	//剩余1分币的个数
		
		//求出1角币的个数
		int numberOfDimes = remainingAmount / 10;
		remainingAmount = remainingAmount % 10;		//剩余1分币的个数
		
		//求出5分币的个数
		int numberOfNickles = remainingAmount / 5;
		remainingAmount = remainingAmount % 5;		//剩余1分币的个数
		
		//一分币的个数
		int numberOfPennies = remainingAmount;
		
		//输出结果
		System.out.println("Your amount " + amount + " consist of \n"+
				"\t" + numberOfOneDollars + " dollars\n" +
				"\t" + numberOfQuarters + " quarters\n" +
				"\t" + numberOfDimes + " dimes\n" +
				"\t" + numberOfNickles + " nickles\n" +
				"\t" + numberOfPennies + " pennies");
		
	}

}


//程序清单2-11 ComputeLoanUsingInputDialog.java
import javax.swing.JOptionPane;

public class ComputeLoanUsingInputDialog {
	public static void main(String[] args){
		//Enter yearly interest rate
		String annualInterestRateString = JOptionPane.showInputDialog(
				"Enter yearly interest rate,for example 8.25: ");
		
		//Covert string to double
		double annualInterestRate =
			Double.parseDouble(annualInterestRateString);
		
		//Obtain monthly interest rate
		double monthlyInterestRate = annualInterestRate / 1200;
		
		//Enter number of years
		String numberOfYearString = JOptionPane.showInputDialog(
				"Enter numbers of years as an integer, \nfor example 5: ");
		
	    //Convert string to int
		int numberOfYears = Integer.parseInt(numberOfYearString);
		
		//Enter loan amount
		String loanString = JOptionPane.showInputDialog(
				"Enter loan amount,for example 120000.95:");
		
		//Convert String to double
		double loanAmount = Double.parseDouble(loanString);
		
		//Calclate 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 = "The monthly payment is " + monthlyPayment +
		"\nThe total payment is " + totalPayment;
		JOptionPane.showMessageDialog(null,output);
			
	}

}