我在绝望需要帮助我需要竞争学校的Java程序！在过去的3天里，我一直在研究这个问题至少3个小时，我无法弄清楚.... =（以下是方向：
编写一个程序，从下面的列表中调用Math类的每个方法，并提供显示调用方法的输出，发送给方法的值以及返回的结果。每个列出的方法都会告诉您使用哪些值。例如：
列出的方法：
double pow(double a, double b): use 2.0 and 3.0.
您的程序将显示：
Math.pow(2.0, 3.0) = 8.0.
当调用接受双精度的方法时，使用至少有一个十进制数字的数字，如上例所示，即使它是零。请记住，带小数的数字是双字面值。尝试使用可以产生易于验证结果的值。
以下是清单：
double pow(double a, double b): Use 3.0 and 2.0
double sqrt(double x): Use 25.0
int max(int a, int b): Use 6 and 2
double max(double a, double b): Use -50.0 and 7.0
static double random()
示例输出：
Math.pow(3.0, 2.0) = 9.0
Math.sqrt(25.0)=5.0
Math.max(6,2)=6
Math.max(-50.0,7.0)=7.0
Math.random()= /*-random value-*/
使用示例中显示的值测试您的程序，修复所有错误。 在程序中添加一个名为randomStudy的方法，该方法没有参数并且不返回任何值。在此方法中，执行以下操作：
一个。声明三个int变量：total，min和max。将总数设置为0，将min设置为11，将max设置为-1。
湾创建一个运行1,000次的循环。在循环体中，生成1到10之间的随机int值，包括1和10。将此数字添加到您的总数中。如果此数字小于min，则使用新数字更新min。如果它大于max，则使用新号码更新max。
℃。循环后，显示以下内容：
最小值：x 最大值：y 平均值：z 用最小值和最大值替换x和y。通过将总数除以1000d来计算z。 从main方法调用新的randomStudy方法。 突出显示并复制Eclipse中显示的输出。将输出粘贴到源代码文件的底部。在结果上方添加文本结果：然后注释掉刚刚添加的文本加上输出文本。您评论的结果应如下所示：
/*
Results:
Math.pow(3.0, 2.0)= 9.0
Math.sqrt(25.0) = 5.0
Math.max(6, 2) = 6
Math.max(-50.0, 7.0) = 7.0
Math.random() = -random number-
Min value: 1
Max value: 10
Average: 5.553
*/
所以，我遇到的问题是关于运行循环1000次的最后一部分，然后显示1,000个数字中最大和最小的数字。并且还显示1,000个数字的平均值。这是我的代码：
class MathMethodsProgram {
public static void main(String[] args) {
// Prints the pow method.
System.out.println("Math.pow(2.0, 3.0) = " + Math.pow(2.0, 3.0));
// Prints the sqrt method
System.out.println("Math.sqrt(25) = " + Math.sqrt(25));
// Prints the max number
System.out.println("Math.max( 6, 3) = " + Math.max(6, 3));
// Prints the max number
System.out.println("Math.max(-50.0,7.0) = " + Math.max(-50.0, 7.0));
// Prints a random number
System.out.println("Math.random(); = " + Math.random());
randomStudy();
}
public static void randomStudy(){
int total = 0;
int min = 11;
int max = -1;
int newtotal = 0;
int i;
int randomInt = 0;
for( i = 0; i < 1000; i++){
randomInt = 1 + (int)( Math.random() * 11);
newtotal = (randomInt + total);
}
if (randomInt < min) {
min = 1 + (int) Math.random();
} else {
System.out.println("Min: " + min);
}
if (randomInt > max) {
max = 1 + (int) Math.random();
} else {
System.out.println("Max: " + max);
}
System.out.println("Min value:" + min);
System.out.println("Max Value:" + max);
System.out.println("Average:"+ newtotal / 1000d);
}
}
当我在Eclipse中运行代码时，这是输出：
Math.pow(2.0, 3.0) = 8.0
Math.sqrt(25) = 5.0
Math.max( 6, 3) = 6
Math.max(-50.0,7.0) = 7.0
Math.random(); = 0.1824716748725944
Min value:1
Max Value:1
Average:0.008
提前致谢
答案 0 :(得分：0)
在1000 for循环中，你有
newtotal = (randomInt + total);
哪个不增加newtotal，它只取最后一个数字。看起来你的最后一个数字是8，所以平均值是0.008。最好是：
total = (randomInt + total);
// Then after the for loop is complete, average = total / 1000;
接下来，为了将randomInt与min / max进行比较，而不是分配新的随机值，您应该根据最后一个随机数分配新的最小值/最大值（这需要在1000 for循环内，而不是在之后） ：
if (randomInt > max) {
max = randomInt;
}
希望这有帮助！
答案 1 :(得分：-1)
您的代码非常接近。
你只需要将你的if语句放在for循环和你写的地方
max = 1 + (int) Math.random();
应为：
max = randomInt;
（对min执行相同操作，使其显示为“min = randomInt;”）
答案 2 :(得分：-1)
这里我将提供我创建的代码。我的目的是为您提供如何创建与我们从 Math 类中获得的函数等效的多个函数的想法。我提供的评论有助于这些课程自我解释，我希望这对你有所帮助。我还包括用于显示数据的对话框，因此如果有人正在寻找有关如何使用 javax.swing 类的帮助，那么这是一个很好的资源。
第一个类 MyMath.java 包含用于执行所有计算的方法。
package com.exercise.lecture2;
/**
* Create a class call "MyMath" that has the following class methods:
* static boolean isEven(int x) --> returns true is number is even
* static long absolute(long x) --> returns the absolute value of x
* static double hypotenuse (double x, double y) --> returns sqrt(x^2 + y^2)
* static double max (double a, double b) --> returns max of a or b
* static double min (double a, double b ) --> returns min of a or b
*
* @author Samuel
*
*/
public class MyMath {
/**
* An even number is an integer which is "evenly divisible" by two.
* This means that if the integer is divided by 2, it yields no remainder.
* Zero is an even number because zero divided by two equals zero, which despite not being a natural number, is an integer.
* Even numbers can be either positive or negative.
*
* @param x
* @return
*/
static boolean isEven(int x){
if (x % 2 == 0)
return true;
else
return false;
}
/**
* In mathematics, the absolute value or modulus of a real number is the number without the sign.
* The absolute value of 2 is 2, the absolute value of -2 is also 2.
*
* @param x
* @return
*/
static long absolute(long x) {
if (x >= 0)
return x;
else
return (-1*x);
}
/**
* The hypotenuse is the side opposite the 90 degrees angle in a right triangle. It is always the longest side.
*
* @param x
* @param y
* @return
*/
static double hypotenuse (double x, double y) {
return Math.sqrt((x * x) + (y * y));
}
/**
* Maximum of two values
* @param a
* @param b
* @return
*/
static double max (double a, double b) {
if (a >= b)
return a;
else
return b;
}
/**
* Minimum of two values
* @param a
* @param b
* @return
*/
static double min (double a, double b ) {
if (a < b)
return a;
else
return b;
}
}
第二个类 MathClassTest.java 包含javax.swing类，以便使用对话框显示。
package com.exercise.lecture2;
import javax.swing.JOptionPane; // importing the javax.swing class in order to use dialog box in my code
/**
* static boolean isEven(int x) --> returns true is number is even
* static long absolute(long x) --> returns the absolute value of x
* static double hypotenuse (double x, double y) --> returns sqrt(x^2 + y^2)
* static double max (double a, double b) --> returns max of a or b
* static double min (double a, double b ) --> returns min of a or b
*
* Write an application that allows the user to select between the above methods and
* returns the response to the user.
*
* @author Samuel
*
*/
public class MathClassTest {
public static void main(String[] args) {
/* used to test the functions on MyMath.java class, here is how all of this begin
* then I change it to make this tester use javax.swing class in order to display using
* dialog boxes.
*
// is Even
System.out.println(MyMath.isEven(-100));
// Absolute value of an integer
System.out.println(MyMath.absolute(-10));
// Hypotenuse of two values
System.out.println(MyMath.hypotenuse(3, 4));
// Max of two values
System.out.println(MyMath.max(3, -4));
// Min of two values
System.out.println(MyMath.min(3, -4));
*/
boolean repeat;
do {
//String name = JOptionPane.showInputDialog(null, "Enter your name", "Enter name", JOptionPane.PLAIN_MESSAGE);
String option = JOptionPane.showInputDialog(null,"Choose 'a' or 'A' to determine if a number is EVEN or not. \n" // options
+ "Choose 'b' or 'B' to determine the ABSOLUTE value of a number. \n" // the (+) sign concatenate the all of the followings Strings as one
+ "Choose 'c' or 'C' to determine the HYPOTENUSE of two values. \n"
+ "Choose 'd' or 'D' to determine the MAXIMUM of two values. \n"
+ "Choose 'e' or 'E' to determine the MINIMUM of two values. \n"
+ "Choose 'q' or 'Q' to quit this simple application. \n\n"
, "My Math class, by S. Mayol", JOptionPane.QUESTION_MESSAGE); // title bar of the dialog box
repeat = true;
if (option.equals("Q") || option.equals("q")) {
JOptionPane.showMessageDialog(null, "Thank you for participating...", "by Samuel Mayol", JOptionPane.INFORMATION_MESSAGE);
repeat = false;
System.exit(0);
} else {
if (option.equals("A")||option.equals("a")){
try { // to prevent that the value inserted is an integer and not a letter
String val = JOptionPane.showInputDialog("Enter a number to deternine if the number is even");
JOptionPane.showMessageDialog(null, "Is the number " + val + " even? " + MyMath.isEven(Integer.valueOf(val)),
"Even", JOptionPane.INFORMATION_MESSAGE); // add a title message on a dialog box
repeat = true;
} catch(Exception e){
JOptionPane.showMessageDialog(null, "The input " + option + " is not valid integer, please try again", "WARNING!!!",
JOptionPane.WARNING_MESSAGE);
}
}
else if (option.equals("B")||option.equals("b")){
try {
String val = JOptionPane.showInputDialog("Enter a number to calculate absolute value of that number");
JOptionPane.showMessageDialog(null, "The absolute value of " + val + " is: " + MyMath.absolute(Long.valueOf(val)),
"Absolute", JOptionPane.INFORMATION_MESSAGE);
repeat = true;
} catch(Exception e){
JOptionPane.showMessageDialog(null, "The input " + option + " is not valid integer, please try again", "WARNING!!!",
JOptionPane.WARNING_MESSAGE);
}
}
else if (option.equals("C")||option.equals("c")){
try {
String val = JOptionPane.showInputDialog("Enter the first side to calculate the hypotenuse");
String val2 = JOptionPane.showInputDialog("Enter the second side to calculate the hypotenuse");
JOptionPane.showMessageDialog(null, "The hypotenuse of " + val + " and " + val2 + " is: " + MyMath.hypotenuse(Double.valueOf(val), Double.valueOf(val2)),
"Hypotenuse", JOptionPane.INFORMATION_MESSAGE);
repeat = true;
} catch(Exception e){
JOptionPane.showMessageDialog(null, "The any of the inputs " + option + " are not valid integer, please try again", "WARNING!!!",
JOptionPane.WARNING_MESSAGE);
}
}
else if (option.equals("D")||option.equals("d")){
try {
String val = JOptionPane.showInputDialog("Enter the first number to calculate the max value");
String val2 = JOptionPane.showInputDialog("Enter the second number to calculate the max value");
JOptionPane.showMessageDialog(null, "The max of " + val + " and " + val2 + " is: " + MyMath.max(Double.valueOf(val), Double.valueOf(val2)),
"Maximum", JOptionPane.INFORMATION_MESSAGE);
repeat = true;
} catch(Exception e){
JOptionPane.showMessageDialog(null, "The any of the inputs " + option + " are not valid integer, please try again", "WARNING!!!",
JOptionPane.WARNING_MESSAGE);
}
}
else if (option.equals("E")||option.equals("e")){
try {
String val = JOptionPane.showInputDialog("Enter the first number to calculate the min value");
String val2 = JOptionPane.showInputDialog("Enter the second number to calculate the min value");
JOptionPane.showMessageDialog(null, "The min of " + val + " and " + val2 + " is: " + MyMath.min(Double.valueOf(val), Double.valueOf(val2)),
"Minimum", JOptionPane.INFORMATION_MESSAGE);
repeat = true;
} catch(Exception e){
JOptionPane.showMessageDialog(null, "The any of the inputs " + option + " are not valid integer, please try again", "WARNING!!!",
JOptionPane.WARNING_MESSAGE);
}
}
else
JOptionPane.showMessageDialog(null, "The input " + option + " is not valid, please try again", "A, B, C, D, E, or Q",
JOptionPane.WARNING_MESSAGE);
}
} while(repeat);
}
}