java语言程序设计基础篇第8版课后答
案
【篇一：java语言程序设计基础篇第八章第十题编程参
考答案】
icequation的类。这个类包括： 代表三个系数的私有数据域a、b、c。 一个参数为a、b、c的构造方法。 a、b、c的三个get方法。 一个名为getdiscriminant()的方法返回判别式，b2-4ac。 一个名为getroot1()和getroot2()的方法返回等式的两个根。 这些方法只有在判别式为非负数时才有用。如果判别式为负，方法返回0。 画出该类的uml图。实现这个类。编写一个测试程序，提示用户输入a、b、c的值，然后显示判别式的结果。如果判别式为正数，显示两个根；如果判别式为0，显示一个根；否则，显示“the equation has no roots”。 代码：
class quadraticequation{ private int a,b,c;
quadraticequation(){ }
public quadraticequation(int a,int b,int c){ this.a=a; this.b=b; this.c=c; }
public int geta(){ return a; }
public int getb(){ return b; }
public int getc(){ return c; }
public int getdiscriminant(){ if(b*b-4*a*c=0) return b*b-4*a*c;
else
return 0; }
public int getroot1(){ if(b*b-4*a*c=0)
return (int)((-b+math.pow(b*b-4*a*c, 0.5))/(2*a)); else
return 0; }
public int getroot2(){ if(b*b-4*a*c=0) else
return 0; } }
public class xiti810 {
public static void main(string[] args){
system.out.println(请输入要计算的方程的系数a、b和c:);java.util.scanner input =new
java.util.scanner(system.in);system.out.print(a=); int a=input.nextint(); system.out.print(b=); int b=input.nextint(); system.out.print(c=); int c=input.nextint();
quadraticequation q=new quadraticequation(a,b,c); q.getdiscriminant();
if(q.getdiscriminant()0)
system.out.println(它们的根为：+q.getroot1()+和+q.getroot2()); else if(q.getdiscriminant()==0)
system.out.println(此方程只有一个根为：+q.getroot1()); else
system.out.println(方程无解); } }
【篇二：java语言程序设计(第8版)第5章完整答案programming exercises(程序练习题)答案完整版】
class exercise01 {
public static void main(string[] args) {
final int pentagonal_numbers_per_line = 10; final int pentagonal_numbers_to_print = 100; int count = 1; int n = 1;
while (count = pentagonal_numbers_to_print) { int pentagonalnumber = getpentagonalnumber(n); n++;
if (count % pentagonal_numbers_per_line == 0) system.out.printf(%-7d\\n, pentagonalnumber); else
system.out.printf(%-7d, pentagonalnumber); count++; } }
public static int getpentagonalnumber(int n) { return n * (3 * n - 1) / 2; } }
5_2
import java.util.scanner; public class exercise02 {
public static void main(string[] args) {
scanner input = new scanner(system.in); //prompt the user to enter an integer system.out.print(enter an interger: ); long number = input.nextlong();
system.out.println(the sum of the digits in + number + is + sumdigits(number)); }
public static int sumdigits(long n) { int sum = 0;
long remainingn = n; }
} do { long digit = remainingn % 10; remainingn = remainingn / 10; sum += digit; } while (remainingn != 0); return sum; 第03题
import java.util.scanner; public class exercise03 {
public static void main(string[] args) {
scanner input = new scanner(system.in);
//prompt the user to enter an integer system.out.print(enter an integer: ); int number = input.nextint(); //display result
system.out.println(is + number + a palindrome? + ispalindrome(number)); }
public static boolean ispalindrome(int number) { if (number == reverse(number)) return true; else
return false; }
public static int reverse(int number) { int reversenumber = 0; do {
int digit = number % 10; number = number / 10;
reversenumber = reversenumber * 10 + digit; } while (number != 0); return reversenumber; }
第04题
import java.util.scanner; public class exercise04 {
public static void main(string[] args) {
scanner input = new scanner(system.in); //prompt the user to enter an integer system.out.print(enter an integer: ); int number = input.nextint(); //display result
system.out.print(the reversal of + number + is ); reverse(number); }
public static void reverse(int number) { int reversenumber = 0; do {
int digit = number % 10; number = number / 10;
reversenumber = reversenumber * 10 + digit; } while (number != 0);
system.out.println(reversenumber); } }
第05题
import java.util.scanner; public class exercise05 {
public static void main(string[] args) {
scanner input = new scanner(system.in); //prompt the user to enter three numbers system.out.print(enter three numbers: ); double num1 = input.nextdouble(); }
double num3 = input.nextdouble(); system.out.print(num1 + + num2 + + num3 + in increasing order: );
displaysortednumbers(num1, num2, num3); } public static void displaysortednumbers(double num1, double num2, double num3) { double max = math.max(math.max(num1,
num2), num3); double min = math.min(math.min(num1, num2), num3); double second = 0; if (num1 != max num1 !=
min)second = num1; if (num2 != max num2 != min)second = num2; if (num3 != max num3 != min)second = num3; system.out.println(min + + second + + max); } 5．6
import java.util.scanner; public class exercise06 {
public static void main(string[] args) {
scanner input = new scanner(system.in); //prompt the user to enter an integer system.out.print(enter an integer: ); int number = input.nextint(); displaypattern(number); }
public static void displaypattern(int n) { int i; int j;
for (i = 1; i = n; i++) { for (j = 0; j n - i; j++) system.out.print( ); }
java语言程序设计基础篇第8版课后答案
