JAVA 皮常德2-7章答案

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JAVA第二章课后习题答案

9.
编写程序，将十进制整数转换为二进制。 public class Tentotwo { public static void main(String[] args) { int a = 123; int remainder; int sum = 0; int k = 1; while(a != 0){ remainder = a %2; a /= 2; sum = sum + remainder * k; k *= 10; } //对目标数字求余 //对目标数字求商 //求和 //改变位数 //定义一个变量并赋给他一个十进制的值 //定义一个变量用于存储余数 //定义一个变量用于存放和 //定义一个变量控制位数
4
Hale Waihona Puke } }7.编写程序，求 100~999 之间所有的三位水仙花数。（水仙花数是指一个 n 位数 ( n≥3 )，它的每个位上的数字的 n 次幂之和等于它本身，例如：1^3 + 5^3+ 3^3 = 153） public class Shuixian { public static void main(String[] args) { int b1, b2, b3; for(int m=101; m<1000; m++) { b3=m/100; b2=m%100/10; b1=m%10; if ((b3*b3*b3+b2*b2*b2+b1*b1*b1)==m) System.out.println(m+"是一个水仙花数"); } } }
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System.out.println("10 进制的 123 转换为 2 进制结果为：" + sum ); } }

Java程序设计各章习题及其答案

Java程序设计各章习题及其答案第一章习题及思考题1、Java程序是由什么组成的？一个程序中必须有public类吗？Java源文件的命名规则是怎样的？答：一个Java源程序是由若干个类组成。

一个Java程序不一定需要有public类：如果源文件中有多个类时，则只能有一个类是public 类；如果源文件中只有一个类，则不将该类写成public也将默认它为主类。

源文件命名时要求源文件主名应与主类（即用public修饰的类）的类名相同，扩展名为.java。

如果没有定义public类，则可以任何一个类名为主文件名，当然这是不主张的，因为它将无法进行被继承使用。

另外，对Applet小应用程序来说，其主类必须为public，否则虽然在一些编译编译平台下可以通过（在BlueJ下无法通过）但运行时无法显示结果。

2、怎样区分应用程序和小应用程序？应用程序的主类和小应用程序的主类必须用public修饰吗？答：Java Application是完整的程序，需要独立的解释器来解释运行；而Java Applet则是嵌在HTML编写的Web页面中的非独立运行程序，由Web浏览器内部包含的Java解释器来解释运行。

在源程序代码中两者的主要区别是：任何一个Java Application 应用程序必须有且只有一个main方法，它是整个程序的入口方法；任何一个Applet小应用程序要求程序中有且必须有一个类是系统类Applet的子类，即该类头部分以extends Applet结尾。

应用程序的主类当源文件中只有一个类时不必用public修饰，但当有多于一个类时则主类必须用public修饰。

小应用程序的主类在任何时候都需要用public来修饰。

3、开发与运行Java程序需要经过哪些主要步骤和过程？答：主要有三个步骤（1）、用文字编辑器notepad（或在Jcreator,Gel, BuleJ,Eclipse, Jbuilder等）编写源文件；(2)、使用Java编译器（如Javac.exe)将.java源文件编译成字节码文件.class；(3)、运行Java程序：对应用程序应通过Java解释器（如java.exe)来运行，而对小应用程序应通过支持Java标准的浏览器(如Microsoft Explorer)来解释运行。

java程序设计课后第二章习题程序答案

public class xiti9{public static void main(String args[]) {int x=4;int y;if(x<1){y=x;}else if(x>=10){y=4*x;}else{y=3*x-2;}System.out.println("y="+y);}}习题12public class xiti12{public static void main(String args[]) {int sum=0;for(int k=1;k<=10;k++){sum=sum+k*k;}System.out.println("sum="+sum); }}习题13public class xiti13{public static void main(String args[]) {intt,a=3,b=5,c=8;if(a<b){t=a;a=b;b=t;}if(a<c){t=a;a=c;c=t;}{t=b;b=c;c=t;}System.out.println("大小顺序输出为："+a+" "+b+" "+c); }}习题14public class xiti14{public static void main(String args[]){int n=1;System.out.print("\n1-100之间的所有素数为：\n"+" 3"); for(int i=1;i<=100;i++){for(int j=2;j<=i/2;j++){if(i%j==0){break;}if(j==i/2){System.out.print(" "+i);n++;}}}System.out.println("\n共有"+n+"个素数。

java第七版课后答案——第二章

//******************************************************************** // AverageOfThree.java Author: Lewis/Loftus//// Solution to Programming Project 2.2//******************************************************************** import java.util.Scanner;public class AverageOfThree{//----------------------------------------------------------------- // Reads three integers from the user and prints their average.//----------------------------------------------------------------- public static void main (String[] args){int num1, num2, num3;double average;Scanner scan = new Scanner (System.in);System.out.print ("Enter the first number: ");num1 = scan.nextInt();System.out.print ("Enter the second number: ");num2 = scan.nextInt();System.out.print ("Enter the third number: ");num3 = scan.nextInt();average = (double) (num1+num2+num3) / 3;System.out.println ("The average is: " + average);}}//******************************************************************** // AverageOfThree2.java Author: Lewis/Loftus//// Alternate solution to Programming Project 2.2//******************************************************************** import java.util.Scanner;public class AverageOfThree2{//----------------------------------------------------------------- // Reads three integers from the user and prints their average.//----------------------------------------------------------------- public static void main (String[] args){int num1, num2, num3;double average;Scanner scan = new Scanner (System.in);System.out.print ("Enter three numbers: ");num1 = scan.nextInt();num2 = scan.nextInt();num3 = scan.nextInt();average = (double) (num1+num2+num3) / 3;System.out.println ("The average is: " + average);}}//******************************************************************** // Balloons.java Author: Lewis/Loftus//// Solution to Programming Project 2.17//********************************************************************import javax.swing.JApplet;import java.awt.*;public class Balloons extends JApplet{//----------------------------------------------------------------- // Draws a set of balloons on strings.//----------------------------------------------------------------- public void paint (Graphics page){setBackground (Color.white);// draw the stringspage.setColor (Color.black);page.drawLine (45, 95, 100, 300);page.drawLine (90, 100, 100, 300);page.drawLine (60, 100, 100, 300);page.drawLine (122, 85, 100, 300);page.drawLine (145, 115, 100, 300);// draw the balloonspage.setColor (Color.blue);page.fillOval (20, 30, 50, 65);page.setColor (Color.yellow);page.fillOval (70, 40, 40, 60);page.setColor (Color.red);page.fillOval (40, 50, 40, 55);page.setColor (Color.green);page.fillOval (100, 30, 45, 55);page.setColor (Color.cyan);page.fillOval (120, 55, 50, 60);}}//******************************************************************** // BigDipper.java Author: Lewis/Loftus//// Solution to Programming Project 2.16//********************************************************************import javax.swing.JApplet;import java.awt.*;public class BigDipper extends JApplet{//----------------------------------------------------------------- // Draws the Big Dipper constellation and some other stars.//----------------------------------------------------------------- public void paint (Graphics page){setBackground (Color.black);page.setColor (Color.white);page.drawLine (100, 80, 110, 120);page.drawLine (110, 120, 165, 115);page.drawLine (165, 115, 175, 70);page.drawLine (100, 80, 175, 70);page.drawLine (175, 70, 245, 20);page.drawLine (245, 20, 280, 30);// Draw some extra starspage.fillOval (50, 50, 4, 4);page.fillOval (70, 150, 3, 3);page.fillOval (90, 30, 3, 3);page.fillOval (220, 140, 4, 4);page.fillOval (280, 170, 3, 3);page.fillOval (310, 100, 4, 4);page.fillOval (360, 20, 3, 3);}}//******************************************************************** // BusinessCard.java Author: Lewis/Loftus//// Solution to Programming Project 2.20//********************************************************************import javax.swing.JApplet;import java.awt.*;public class BusinessCard extends JApplet{//----------------------------------------------------------------- // Draws a business card.//----------------------------------------------------------------- public void paint (Graphics page){setBackground (Color.yellow);page.setColor (Color.red);page.fillOval (10, 20, 60, 60);page.setColor (Color.cyan);page.fillRect (25, 35, 130, 25);page.setColor (Color.black);page.drawString ("James C. Kerplunk", 35, 50);page.drawString ("President and CEO", 85, 80);page.drawString ("Origin Software, Inc.", 85, 100);page.drawLine (225, 20, 225, 80);page.drawLine (195, 50, 255, 50);page.setColor (Color.blue);page.drawString ("where it all begins...", 115, 135);}}//******************************************************************** // ChangeCounter.java Author: Lewis/Loftus//// Solution to Programming Project 2.10//******************************************************************** import java.util.Scanner;public class ChangeCounter{//----------------------------------------------------------------- // Computes the total value of a collection of coins.//----------------------------------------------------------------- public static void main (String[] args){int quarters, dimes, nickels, pennies;int total, dollars, cents;Scanner scan = new Scanner(System.in);System.out.print ("Enter the number of quarters: ");quarters = scan.nextInt();System.out.print ("Enter the number of dimes: ");dimes = scan.nextInt();System.out.print ("Enter the number of nickels: ");nickels = scan.nextInt();System.out.print ("Enter the number of pennies: ");pennies = scan.nextInt();total = quarters * 25 + dimes * 10 + nickels * 5 + pennies;dollars = total / 100;cents = total % 100;System.out.println ("Total value: " + dollars + " dollars and " + cents + " cents.");}}//******************************************************************** // DrawName.java Author: Lewis/Loftus//// Solution to Programming Project 2.15//********************************************************************import javax.swing.JApplet;import java.awt.*;public class DrawName extends JApplet{//----------------------------------------------------------------- // Draws a name.//----------------------------------------------------------------- public void paint (Graphics page){setBackground (Color.cyan);page.setColor (Color.black);page.drawString ("John A. Lewis", 50, 50);}}//******************************************************************** // FloatCalculations.java Author: Lewis/Loftus//// Solution to Programming Project 2.4//******************************************************************** import java.util.Scanner;public class FloatCalculations{//----------------------------------------------------------------- // Reads two floating point numbers and prints their sum,// difference, and product.//----------------------------------------------------------------- public static void main (String[] args){float num1, num2;Scanner scan = new Scanner (System.in);System.out.print ("Enter the first number: ");num1 = scan.nextFloat();System.out.print ("Enter the second number: ");num2 = scan.nextFloat();System.out.println ("Their sum is: " + (num1+num2));System.out.println ("Their difference is: " + (num1-num2));System.out.println ("Their product is: " + (num1*num2));}}//******************************************************************** // Fraction.java Author: Lewis/Loftus//// Solution to Programming Project 2.13//******************************************************************** import java.util.Scanner;public class Fraction{//----------------------------------------------------------------- // Computes the floating point equivalent of a fraction.//----------------------------------------------------------------- public static void main (String[] args){int numerator, denominator;float value;Scanner scan = new Scanner(System.in);System.out.print ("Enter the numerator: ");numerator = scan.nextInt();System.out.print ("Enter the denominator: ");denominator = scan.nextInt();value = (float) numerator / denominator;System.out.println ("Floating point equivalent: " + value);}}//******************************************************************** // HousePicture.java Author: Lewis/Loftus//// Solution to Programming Project 2.19//********************************************************************import javax.swing.JApplet;import java.awt.*;public class HousePicture extends JApplet{//----------------------------------------------------------------- // Draws a house scene.//----------------------------------------------------------------- public void paint (Graphics page){setBackground (Color.cyan);page.setColor (Color.gray);page.fillRect (0, 200, 400, 50); // groundpage.setColor (Color.blue);page.fillRect (50, 125, 300, 100); // housepage.setColor (Color.green);page.fillRect (180, 175, 40, 50); // doorpage.setColor (Color.yellow);page.fillRect (100, 155, 40, 25); // windowpage.fillRect (260, 155, 40, 25); // windowpage.setColor (Color.black);page.fillRect (40, 100, 320, 40); // roofpage.fillOval (210, 200, 6, 6); // doorknobpage.setColor (Color.red);page.fillRect (80, 80, 20, 40); // chimneypage.setColor (Color.darkGray);page.fillOval (80, 60, 20, 20); // smokepage.fillOval (85, 50, 15, 25); // smokepage.fillOval (90, 45, 15, 20); // smokepage.setColor (Color.white);page.fillOval (200, 30, 80, 40); // cloudpage.fillOval (230, 40, 80, 40); // cloud}}//******************************************************************** // InfoParagraph.java Author: Lewis/Loftus//// Solution to Programming Project 2.3//********************************************************************import java.util.Scanner;public class InfoParagraph{//----------------------------------------------------------------- // Reads information about a person and incorporates it into an// output paragraph.//----------------------------------------------------------------- public static void main (String[] args){String name, age, college, pet;Scanner scan = new Scanner (System.in);System.out.print ("What is your name? ");name = scan.nextLine();System.out.print ("How old are you? ");age = scan.nextLine();System.out.print ("What college do you attend? ");college = scan.nextLine();System.out.print ("What is your pet's name? ");pet = scan.nextLine();System.out.println ();System.out.print ("Hello, my name is " + name + " and I am ");System.out.print (age + " years\nold. I'm enjoying my time at "); System.out.print (college + ", though\nI miss my pet " + pet);System.out.println (" very much!");System.out.println ();}}//******************************************************************** // Lincoln4.java Author: Lewis/Loftus//// Solution to Programming Project 2.1//********************************************************************public class Lincoln4{//----------------------------------------------------------------- // Prints a quote from Abraham Lincoln, including quotation// marks.//----------------------------------------------------------------- public static void main (String[] args){System.out.println ("A quote by Abraham Lincoln:");System.out.println ("\"Whatever you are, be a good one.\"");}}//******************************************************************** // MilesToKilometers.java Author: Lewis/Loftus//// Solution to Programming Project 2.6//******************************************************************** import java.util.Scanner;public class MilesToKilometers{//----------------------------------------------------------------- // Converts miles into kilometers. The value for miles is read// from the user.//----------------------------------------------------------------- public static void main (String[] args){final double MILES_PER_KILOMETER = 1.60935;double miles, kilometers;Scanner scan = new Scanner(System.in);System.out.print ("Enter the distance in miles: ");miles = scan.nextDouble();kilometers = MILES_PER_KILOMETER * miles;System.out.println ("That distance in kilometers is: " +kilometers);}}//******************************************************************** // MoneyConversion.java Author: Lewis/Loftus//// Solution to Programming Project 2.11//******************************************************************** import java.util.Scanner;public class MoneyConversion{//----------------------------------------------------------------- // Reads a monetary amount and computes the equivalent in bills// and coins.//----------------------------------------------------------------- public static void main (String[] args){double total;int tens, fives, ones, quarters, dimes, nickels;int remainingCents;Scanner scan = new Scanner(System.in);System.out.print ("Enter monetary amount: ");total = scan.nextDouble();remainingCents = (int) (total * 100);tens = remainingCents / 1000;remainingCents %= 1000;fives = remainingCents / 500;remainingCents %= 500;ones = remainingCents / 100;remainingCents %= 100;quarters = remainingCents / 25;remainingCents %= 25;dimes = remainingCents / 10;remainingCents %= 10;nickels = remainingCents / 5;remainingCents %= 5;System.out.println ("That's equivalent to:");System.out.println (tens + " ten dollar bills");System.out.println (fives + " five dollar bills");System.out.println (ones + " one dollar bills");System.out.println (quarters + " quarters");System.out.println (dimes + " dimes");System.out.println (nickels + " nickels");System.out.println (remainingCents + " pennies");}}//******************************************************************** // OlympicRings.java Author: Lewis/Loftus//// Solution to Programming Project 2.18//********************************************************************import javax.swing.JApplet;import java.awt.*;public class OlympicRings extends JApplet{//----------------------------------------------------------------- // Draws the olympic logo.//----------------------------------------------------------------- public void paint (Graphics page){final int DIAMETER = 50;setBackground (Color.lightGray);page.setColor (Color.blue);page.drawOval (30, 40, DIAMETER, DIAMETER);page.setColor (Color.yellow);page.drawOval (60, 70, DIAMETER, DIAMETER);page.setColor (Color.black);page.drawOval (90, 40, DIAMETER, DIAMETER);page.setColor (Color.green);page.drawOval (120, 70, DIAMETER, DIAMETER);page.setColor (Color.red);page.drawOval (150, 40, DIAMETER, DIAMETER);}}//******************************************************************** // PieChart.java Author: Lewis/Loftus//// Solution to Programming Project 2.22//******************************************************************** import javax.swing.JApplet;import java.awt.*;public class PieChart extends JApplet{//----------------------------------------------------------------- // Draws the pie chart with equal sections.//----------------------------------------------------------------- public void paint (Graphics page){setBackground (Color.lightGray);page.setColor (Color.blue);page.fillArc (70, 25, 100, 100, 0, 45);page.setColor (Color.yellow);page.fillArc (70, 25, 100, 100, 45, 45);page.setColor (Color.black);page.fillArc (70, 25, 100, 100, 90, 45);page.setColor (Color.green);page.fillArc (70, 25, 100, 100, 135, 45);page.setColor (Color.red);page.fillArc (70, 25, 100, 100, 180, 45);page.setColor (Color.magenta);page.fillArc (70, 25, 100, 100, 225, 45);page.setColor (Color.cyan);page.fillArc (70, 25, 100, 100, 270, 45);page.setColor (Color.orange);page.fillArc (70, 25, 100, 100, 315, 45);}}//******************************************************************** // Seconds.java Author: Lewis/Loftus//// Solution to Programming Project 2.8//******************************************************************** import java.util.Scanner;public class Seconds{//----------------------------------------------------------------- // Computes the total number of seconds for a given number of// hours, minutes, and seconds.//-----------------------------------------------------------------public static void main (String[] args){final int SECONDS_PER_HOUR = 3600;final int SECONDS_PER_MINUTE = 60;int seconds, minutes, hours, totalSeconds;Scanner scan = new Scanner(System.in);System.out.print ("Enter the number of hours: ");hours = scan.nextInt();System.out.print ("Enter the number of minutes: ");minutes = scan.nextInt();System.out.print ("Enter the number of seconds: ");seconds = scan.nextInt();totalSeconds = hours * SECONDS_PER_HOUR +minutes * SECONDS_PER_MINUTE +seconds;System.out.println ();System.out.println ("Total seconds: " + totalSeconds);}}//******************************************************************** // Seconds2.java Author: Lewis/Loftus//// Solution to Programming Project 2.9//******************************************************************** import java.util.Scanner;public class Seconds2{//----------------------------------------------------------------- // Computes the number of hours, minutes, and seconds that are// equivalent to the number of seconds entered by the user.//----------------------------------------------------------------- public static void main (String[] args){final int SECONDS_PER_HOUR = 3600;final int SECONDS_PER_MINUTE = 60;int seconds, minutes, hours;Scanner scan = new Scanner(System.in);System.out.print ("Enter the number of seconds: ");seconds = scan.nextInt();hours = seconds / SECONDS_PER_HOUR;seconds = seconds % SECONDS_PER_HOUR; // remaining secondsminutes = seconds / SECONDS_PER_MINUTE;seconds = seconds % SECONDS_PER_MINUTE; // remaining secondsSystem.out.println ();System.out.println ("Hours: " + hours);System.out.println ("Minutes: " + minutes);System.out.println ("Seconds: " + seconds);}}//******************************************************************** // ShadowName.java Author: Lewis/Loftus//// Solution to Programming Project 2.21//********************************************************************import javax.swing.JApplet;import java.awt.*;public class ShadowName extends JApplet{//----------------------------------------------------------------- // Draws a name with a slightly offset shadow.//----------------------------------------------------------------- public void paint (Graphics page){setBackground (Color.yellow);page.setColor (Color.black);page.drawString ("John A. Lewis", 50, 50);page.setColor (Color.red);page.drawString ("John A. Lewis", 49, 49);}}//******************************************************************** // Snowman2.java Author: Lewis/Loftus//// Solution to Programming Project 2.14//********************************************************************import javax.swing.JApplet;import java.awt.*;public class Snowman2 extends JApplet{//----------------------------------------------------------------- // Draws a snowman with added features.//----------------------------------------------------------------- public void paint (Graphics page){final int MID = 130;final int TOP = 50;setBackground (Color.cyan);page.setColor (Color.blue);page.fillRect (0, 175, 300, 50); // groundpage.setColor (Color.yellow);page.fillOval (260, -40, 80, 80); // sunpage.setColor (Color.white);page.fillOval (MID-20, TOP, 40, 40); // headpage.fillOval (MID-35, TOP+35, 70, 50); // upper torsopage.fillOval (MID-50, TOP+80, 100, 60); // lower torsopage.setColor (Color.red);page.fillOval (MID-3, TOP+50, 6, 6); // buttonpage.fillOval (MID-3, TOP+60, 6, 6); // buttonpage.setColor (Color.black);page.fillOval (MID-10, TOP+10, 5, 5); // left eyepage.fillOval (MID+5, TOP+10, 5, 5); // right eyepage.drawArc (MID-10, TOP+20, 20, 10, 10, 160); // frownpage.drawLine (MID-25, TOP+60, MID-50, TOP+40); // left armpage.drawLine (MID+25, TOP+60, MID+55, TOP+60); // right armpage.drawLine (MID-20, TOP+5, MID+20, TOP+5); // brim of hatpage.fillRect (MID-15, TOP-20, 30, 25); // top of hatpage.drawString ("John Lewis", 20, 20); // artist}}//******************************************************************** // SquareCalculations.java Author: Lewis/Loftus//// Solution to Programming Project 2.12//******************************************************************** import java.util.Scanner;public class SquareCalculations{//----------------------------------------------------------------- // Computes a square's perimeter and area given the length of// one side.//----------------------------------------------------------------- public static void main (String[] args){int side, perimeter, area;Scanner scan = new Scanner(System.in);System.out.print ("Enter the length of a square's side: ");side = scan.nextInt();perimeter = side * 4;area = side * side;System.out.println ("Perimeter: " + perimeter);System.out.println ("Area: " + area);}}//********************************************************************// TempConverter2.java Author: Lewis/Loftus//// Solution to Programming Project 2.5//******************************************************************** import java.util.Scanner;public class TempConverter2{//----------------------------------------------------------------- // Computes the Celsius equivalent of a Fahrenheit value read// from the user. Uses the formula C = (5/9)(F - 32).//----------------------------------------------------------------- public static void main (String[] args){final int BASE = 32;final double CONVERSION_FACTOR = 5.0 / 9.0;double celsiusTemp, fahrenheitTemp;Scanner scan = new Scanner(System.in);System.out.print ("Enter a Fahrenheit temperature: ");fahrenheitTemp = scan.nextDouble();celsiusTemp = CONVERSION_FACTOR * (fahrenheitTemp - BASE);System.out.println ("Celsius Equivalent: " + celsiusTemp);}}//******************************************************************** // TravelTime.java Author: Lewis/Loftus//// Solution to Programming Project 2.7//******************************************************************** import java.util.Scanner;public class TravelTime{//----------------------------------------------------------------- // Converts miles into kilometers. The value for miles is read// from the user.//-----------------------------------------------------------------public static void main (String[] args){int speed, distance;double time;Scanner scan = new Scanner(System.in);System.out.print ("Enter the speed: ");speed = scan.nextInt();System.out.print ("Enter the distance traveled: ");distance = scan.nextInt();time = (double) distance / speed;System.out.println ("Time elapsed during trip: " + time); }}。

【VIP专享】Java2实用教程(第四版)1-8章答案

习题二（第 2 章）
一、问答题 1．用来标识类名、变量名、方法名、类型名、数组名、文件名的有效字符序列称为标识符。标识符由字母、下划线、美元符号和数字组成，第一个字符不能是数字。false 不是标识符。
2．关键字就是 Java 语言中已经被赋予特定意义的一些单词，不可以把关键字作为名字来用。不是关键字。class implements interface extends abstract。 3．boolean，char，byte，short，int，long，float，double。 4．float 常量必须用 F 或 f 为后缀。double 常量用 D 或 d 为后缀，但允许省略后缀。 5．一维数组名.length。二维数组名.length。二、选择题 1．C。2．ADF。3．B。4．BE。5．【代码 2】【代码 3】【代码 4】【代码 5】。6．B。
6.培养学生观察、思考、对比及分析综合的能力。过程与方法1.通过观察蚯蚓教的学实难验点，线培形养动观物察和能环力节和动实物验的能主力要；特2征.通。过教对学观方察法到与的教现学象手分段析观与察讨法论、，实对验线法形、动分物组和讨环论节法动教特学征准的备概多括媒，体继课续件培、养活分蚯析蚓、、归硬纳纸、板综、合平的面思玻维璃能、力镊。子情、感烧态杯度、价水值教观1和.通过学理解的蛔1虫.过观适1、察于程3观阅六蛔寄.内列察读、虫生出蚯材让标容生3根常蚓料学本教活.了据见身：生，师的2、解问的体巩鸟总看活形作用蛔题线的固类结雌动态业手虫自形练与本雄学、三：摸对学动状习人节蛔生结4、、收一人后物和同类课虫活构请一蚯集摸体回并颜步关重的动、学、蚓鸟蚯的答归色学系点形教生生让在类蚓危问纳。习从并状学理列学平的害题线蚯四线人归、意特出四生面体以形蚓、形类纳大图点常、五观玻存表及动的鸟请动文本小引以见引、察璃现，预物身类 3学物明节有言及的、导巩蚯上状是防的体之生和历课什根蚯环怎学固蚓和，干感主是所列环史学么据蚓节二样生练引牛鸟燥染要否以举节揭到不上适动、区回习导皮类还的特分分蚯动晓的同节于物让分答。学纸减是方征节布蚓物起一，课穴并学蚯课生上少湿法。?广的教，些体所居归在生蚓前回运的润；4泛益学鸟色生纳.靠物完的问答动原的4蛔，处目类习和活环.近在成前题蚯的因？了虫以。标就生体的节身其实端并蚓快及触解寄上知同物表内特动体结验和总利的慢我摸蚯生适识人学有容点物前构并后结用生一国蚯蚓在于与类的什，的端中思端线问活样的蚓人飞技有基么引进主的的考?形题环吗十体生行能着本特出要几变以动，境？大节活的1密方征本“特节化下物.让并为珍近习会形理切法。课生征有以问的小学引什稀腹性态解的。2课物。什游题主.结生出么鸟面和起结蛔关观题体么戏：要利明蚯？类处适哪构虫系察：的特的特用确蚓等，于些特适。蛔章形殊形征板，这资是穴疾点于可虫我态结式。书生种料光居病是寄的们结构，五小物典，滑生？重生鸟内学构，学、结的型以还活5要生类部习与.其习巩鸟结的爱是如原活生结了功颜消固类构线鸟粗形何因的存构腔能色化练适特形护糙态预之结的，肠相是系习于点动鸟？、防一构现你动适否统。飞都物为结蛔。和状认物应与的行是。主构虫课生却为和”其结的与题、病本理不蛔扁的他构特环以生？8特乐虫形观部特8征境小理三页点观的动位点梳相组等、这；，哪物教相，理适为方引些2鸟，育同师.知应单面导鸟掌类结了；？生识的位学你握日构解2互.。办特生认线益特了通动手征观识形减点它过，抄；察吗动少是们理生报5蛔？物，与的解.参一了虫它和有寄主蛔与份解结们环些生要虫其。蚯构都节已生特对中爱蚓。会动经活征人培鸟与飞物灭相。类养护人吗的绝适这造兴鸟类？主或应节成趣的为要濒的课情关什特临？就危感系么征灭来害教；？；绝学，育，习使。我比学们它生可们理以更解做高养些等成什的良么两好。类卫动生物习。惯根的据重学要生意回义答；的3.情通况过，了给解出蚯课蚓课与题人。类回的答关：系线，形进动行物生和命环科节学动价环值节观动的物教一育、。根教据学蛔重虫点病1.引蛔出虫蛔适虫于这寄种生典生型活的线结形构动和物生。理二特、点设；置2.问蚯题蚓让的学生生活思习考性预和习适。于穴居生活的形态、结构、生理等方面的特征；3.线形动物和环节动物的主要特征。

JAVA 皮常德2-7章答案

二1.角谷猜想：任何一个正整数n，如果它是偶数则除以二，如果是奇数则乘以3再加上1，这样得到一个新的整数，如此继续进行上述处理，则最后得到的数一定是1，编写应用程序和小程序分别验证：3~10000之间任何正整数都满足上述规则。

2.编写一个程序模拟同时掷2个骰子。

程序要用Math.random( )模拟产生第一个骰子，然后再产生第二个骰子，将2个结果相加。

和等于7的可能性最大，等于2和12的可能性最小。

下图表示了出现36种情况组合。

程序模拟掷3600次骰子，判断求和结果是否合理，共有6种情况的和是7，故在3600次掷骰子的结果中应当有1/6的可能性是7。

123456 1234567 2345678 3456789 45678910 567891011 6789101112一、实验步骤：1.应用程序：package cp2;public class a4 {public static void main(String[] args) {boolean a=true;int j;for(int i=3;i<=10000;i++){for(j=i;j>1;){if(j%2==0){j=j/2;}else{j=j*3+1;}}if(j!=1){a=false;break;}}System.out.println(a);}}运行结果：true小程序：package cp2;import java.awt.*;import java.applet.*;public class a5 extends Applet{Label lab1;TextField input1;int num1=1;public void init(){lab1=new Label("任意输入3~10000的一个整数");input1=new TextField(10);add(lab1);add(input1);}public boolean action(Event e,Object o){num1=Integer.parseInt(input1.getText());showStatus("");input1.setText("");repaint();showStatus("这个数是"+num1);return true;}public void paint(Graphics g){int xpos=50,ypos=50,i=0;int xpos1=xpos;while(num1!=1){if(num1%2==0){num1=num1/2;g.drawString(Integer.toString(num1), xpos, ypos);}else{num1=num1*3+1;g.drawString(Integer.toString(num1), xpos, ypos);}xpos=xpos+50;i++;if(i%5==0){ypos=ypos+10;xpos=xpos1;}}}}运行结果：2.程序：package cp2;import java.awt.*;import java.applet.*;public class a6 extends Applet{Label lab;TextField input;int a,b,t2,t3,t4,t5,t6,t7,t8,t9,t10,t11,t12;double i2,i3,i4,i5,i6,i7,i8,i9,i10,i11,i12;public void init(){lab=new Label("输入次数");input=new TextField(10);add(lab);add(input);}public boolean action(Event e,Object o){int time=Integer.parseInt(input.getText()); showStatus("");input.setText("");showStatus("模拟次数"+time);t2=t3=t4=t5=t6=t7=t8=t9=t10=t11=t12=0;for(int i=1;i<=time;i++){a=(int)(Math.random()*6+1);b=(int)(Math.random()*6+1);switch(a+b){case 12:t12++;break;case 11:t11++;break;case 10:t10++;break;case 9:t9++;break;case 8:t8++;break;case 7:t7++;break;case 6:t6++;break;case 5:t5++;break;case 4:t4++;break;case 3:t3++;break;case 2:t2++;break;}i12=(double)t12/i;i11=(double)t11/i;i10=(double)t10/i;i9=(double)t9/i;i8=(double)t8/i;i7=(double)t7/i;i6=(double)t6/i;i5=(double)t5/i;i4=(double)t4/i;i3=(double)t3/i;i2=(double)t2/i;repaint();}//repaint();return true;}public void paint(Graphics g){g.drawString("各种和的概率：",25,40);g.drawString("12:"+i12,25,55);g.drawString("11:"+i11,25,70);g.drawString("10:"+i10,25,85);g.drawString("9:"+i9,25,100);g.drawString("8:"+i8,25,115);g.drawString("7:"+i7,25,130);g.drawString("6:"+i6,25,145);g.drawString("5:"+i5,25,160);g.drawString("4:"+i4,25,175);g.drawString("3:"+i3,25,190);g.drawString("2:"+i2,25,205);}}运行结果：三一、实验内容：1.采用循环语句打印如下图形：* *** ***** ******* ****2．编写一个applet，采用公式：e x=1+x1/1!+x2/2!+……..+x n/n!.三、实验步骤：1．程序：package cp3;import java.awt.*;import java.applet.*;public class a1 extends Applet{Label lab;TextField input;int a,b[]=new int[20],i,j;public void init(){lab=new Label("输入数字");input=new TextField(10);add(lab);add(input);}public boolean action(Event e,Object o){a=Integer.parseInt(input.getText());input.setText("");repaint();return true;}public void paint(Graphics g){for(int i=0;a!=0;i++){b[i]=a%10;a/=10;}for(j=0;b[j]!=0;j++);for(int t=--j;t>=0;t--){g.drawString(Integer.toString(b[t]),j*20-t*20,55); }for(i=0;i<b.length;i++){b[i]=0;}}}运行结果：* *** ***** ******* ********* *****2:程序：package cp3;import java.awt.*;import java.applet.*;public class a6 extends Applet{Label lab1,lab2;TextField input1,input2;int a,b,i;double sum=0;public class aa{int mult(int n){int s=1;for(int j=1;j<=n;j++)s*=j;return s;}}public void init(){lab1=new Label("输入x大小");input1=new TextField(10);lab2=new Label("输入n值");input2=new TextField(10);add(lab1);add(input1);add(lab2);add(input2);}public boolean action(Event e,Object o){a=Integer.parseInt(input1.getText()); b=Integer.parseInt(input2.getText()); input1.setText("");input2.setText("");showStatus("");sum=0;aa c=new aa();for(i=0;i<=b;i++){sum+=(double)(Math.pow(a,i))/(double)c.mult(i);}showStatus("结果为"+sum);return true;}}输入x=1,n=30时的运行结果：四二、实验内容：1.定义一个类，它包含了一个int类型的变量x、若干个构造函数（根据你的需要）和一个输出方法show( )。

JAVA语言程序设计第六版编程答案第二章

Double pay = Double.parseDouble(JOptionPane.showInputDialog(null,"请输入费用："));
Double tax = Double.parseDouble(JOptionPane.showInputDialog(null,"请输入提成："));
Scanner input = new Scanner(System.in);
int num = input.nextInt();
if(num<0 || num>127){
System.out.println("输入有误！程序终止运行");
double futureInvestmentValue = investmentAmount*Math.pow((monthlyInverestRate+1.0),numberOfYear*12);
String output = "将来的资金额为：" + futureInvestmentValue;
", 高度为：" + height +
"的圆柱体积是：" + volume);
}
}
2_3
import javax.swing.JOptionPane;
}
}
2_2
import javax.swing.JOptionPane;
public class Exercise2_2 {
public static void main(String[] args) {
double radius, height;

《Java2实用教程》课后习题参考答案

Java2 实用教程(第三版)课后习题参考答案第1 章Java 入门1. 开发与运行Jav a 程序需要经过哪些主要步骤和过程？答：（ 1）编写Java 源文件:使用文本编辑器（Edit 或记事本），拓展名为.java（2）编译Java 源文件:使用Java 编译器（javac.exe）。

得到字节码文件*.class（3）运行Java 程序:Java 应用程序使用Java 解释器（java.exe）执行字节码文件；Java 小应用程序使用支持Java 标准的浏览器来执行。

2. 怎样区分应用程序和小应用程序？应用程序的主类或小应用程序的主类必须用public 修饰吗？答：①应用程序必须有main 方法，这个方法是程序执行的入口。

小应用程序没有main 方法。

②应用程序的主类不一定用public 修饰；小应用程序的主类必须用public 修饰。

3. Jav a 程序是由什么组成的？一个程序中必须要有public 类吗？Jav a 源文件的命名规则是怎样的？答：①Java 程序由类组成。

②应用程序可以没有public 类；小应用程序一定有一个类是public 类（主类）。

③应用程序:如果只有一个类，源文件名与该类的类名相同，拓展名为.java；有多个类时，如果有public 类（最多一个）,源文件名与public 类的类名相同，拓展名是.java；没有public 类，源文件名与任何一个类的类名相同即可，拓展名为.java。

小应用程序:源文件名与主类的类名相同，拓展名是.java。

4. 在运行小程序的HTM L 文件中可以使用codebas e 属性指定小程序的字节码所驻留的目录。

如果不使用codebas e 属性，小程序的字节码文件必须和运行它的HTM L 文件在同一目录中。

编写一个小程序并将小程序的字节码存放在某个目录中，比如C:\5000；把运行该小程序的HTM L 文件（注意其中的codebas e 属性）:<applet code=你的小程序的字节码width=200 height=300 codebase=C: \5000></applet>存放在另一个目录中。

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2.编写一个程序模拟同时掷2个骰子。

程序要用Math.random( )模拟产生第一个骰子，然后再产生第二个骰子，将2个结果相加。

和等于7的可能性最大，等于2和12的可能性最小。

下图表示了出现36种情况组合。

程序模拟掷3600次骰子，判断求和结果是否合理，共有6种情况的和是7，故在3600次掷骰子的结果中应当有1/6的可能性是7。

编程：从键盘输入一个数，将这个数传递给这个类的x，采用方法show( )逆序输出这个数。

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