我正在尝试编写一个程序，允许用户输入一系列考试成绩作为整数。
我希望输出看起来像：
输入一个整数，或输入-99退出：80
输入一个整数，或输入-99退出：95
输入一个整数，或输入-99退出：65
输入一个整数，或输入-99退出：-99
最大：95 最小：65
第二轮：
输入一个整数，或输入-99退出：-99
您没有输入任何数字。
我得到了第一部分，但是当我输入-99时，我似乎无法找到如何获得“你没有输入任何数字”行。
这是我到目前为止所做的。
import java.util.Scanner; // Needed for the Scanner class
/**
This program shows the largest and smallest exam scores. The user
enters a series of exam scores, then -99 when finished.
UPDATED to show even number of points using if-statement
*/
public class Grades
{
public static void main(String[] args)
{
int score = 0; // Exam score
int min = 100; // Hold smallest score
int max = 0; // Hold largest score
// Create a Scanner object for keyboard input.
Scanner keyboard = new Scanner(System.in);
// Display general instructions.
System.out.println("Enter an integer, or -99 to quit: ");
System.out.println();
// Get the first exam score.
System.out.print("Enter an integer, or -99 to quit: ");
score = keyboard.nextInt();
// Input exam scores until -99 is entered.
while (score != -99)
{
// Add points to totalPoints.
if (score > max)
max = score;
if (score < min)
min = score;
// Get the next number of points.
System.out.print("Enter an integer, or -99 to quit: ");
score = keyboard.nextInt();
}
// Display the largest and smallest score.
System.out.println("Largest: " + max);
System.out.println("Smallest: " + min);
}
}
答案 0 :(得分：1)
如何引入一个计算输入数字的变量并在while循环中增加？
或者作为替代方案，如果数字发生变化，您可以在while循环后检查：
if(min > max) {
System.out.println("You did not enter any numbers.");
}
else {
System.out.println("Largest: " + max);
System.out.println("Smallest: " + min);
}
这样可行，因为在开始时，您将min变量初始化为100，将max变量初始化为0，这将导致true min > max检查是否输入了数字。
答案 1 :(得分：1)
以下代码在您输入0＆amp;时不起作用100：
if (max = 0 && min = 100)
System.out.println("You did not enter any numbers");
else{
System.out.println("Largest: " + max);
System.out.println("Smallest: " + min);
}
使用额外的布尔变量检查任何不同于-99的输入
是一个不错的选择public class Grades
{
public static void main(String[] args)
{
int score = 0; // Exam score
int min = 100; // Hold smallest score
int max = -100; // Hold largest score
boolean isAnyScore = false;
// Create a Scanner object for keyboard input.
Scanner keyboard = new Scanner(System.in);
// Display general instructions.
System.out.print("Enter an integer, or -99 to quit: ");
System.out.println();
// Input exam scores until -99 is entered.
while(true)
{
System.out.print("Enter an integer, or -99 to quit: ");
score = keyboard.nextInt(); //Get the exam score.
if(score == -99) { break; }
else { isAnyScore = true; }
// Add points to totalPoints.
if (score > max) { max = score; }
if (score < min) { min = score; }
}
// Display the largest and smallest score.
if(!isAnyScore) { System.out.println("You did not enter any numbers"); }
else
{
System.out.println("Largest: " + max);
System.out.println("Smallest: " + min);
}
}
}
变量isAnyScore为false。当你在第一次循环运行中输入-99时，它仍然是false，因为没有赋值。当你在第一次循环运行中输入-99以外的东西时，它总是为真（它将在任何循环中作为true运行）。当isAnyScore从false变为true时，它始终是真的，因为你总是分配true，永远不会伪造。
答案 2 :(得分：0)
在您的计划结束时：
if (max == 0 && min == 100)
System.out.println("You did not enter any numbers");
else{
System.out.println("Largest: " + max);
System.out.println("Smallest: " + min);
}
答案 3 :(得分：0)
public static void main(String[] args) {
int score = 0; // Exam score
int min = 100; // Hold smallest score
int max = 0; // Hold largest score
boolean isNumberEntered = false; //Test if any number has been entered.
// Create a Scanner object for keyboard input.
Scanner keyboard = new Scanner(System.in);
// Input exam scores until -99 is entered.
while (score != -99)
{
// Get the next number of points.
System.out.print("Enter an integer, or -99 to quit: ");
score = keyboard.nextInt();
if (score == -99) {
break;
} else {
// If the first number is entered
if (!isNumberEntered)
isNumberEntered = true;
// Add points to totalPoints.
if (score > max)
max = score;
if (score < min)
min = score;
}
}
if (isNumberEntered) {
// Display the largest and smallest score.
System.out.println("Largest: " + max);
System.out.println("Smallest: " + min);
} else {
System.out.println("You did not enter any numbers!");
}
}
如果你试试这个怎么样？你想留在循环中，直到添加了一个数字或者是你想要它的方式吗？
答案 4 :(得分：0)
我认为等级在100到0之间。所以我改变了一点。如果输入是＆lt; 0和＆gt; 100，输出为＆＃34;您没有输入任何数字＆＃34;。
package chapter5;
import java.util.Scanner;
public class Grades
{
public static void main(String[] args)
{
int min = 100; // Hold smallest score
int max = 0; // Hold largest score
// Create a Scanner object for keyboard input.
Scanner keyboard = new Scanner(System.in);
// Display general instructions.
System.out.print("Enter an integer, or -99 to quit: ");
int score = keyboard.nextInt();
if(score<0||score>100){
System.out.println("You did not enter any numbers.");
}
// Input exam scores until -99 is entered.
if(score>=0||score<=100){
while (score != -99)
{
// Add points to totalPoints.
if (score > max)
max = score;
if (score < min)
min = score;
// Get the next number of points.
System.out.print("Enter an integer, or -99 to quit: ");
score = keyboard.nextInt();
if(score==-99){
System.out.println();}
else if(score!=-99&&score<0||score>100){
System.out.println("You did not enter any numbers.");}
}
}
// Display the largest and smallest score.
System.out.println("Largest: " + max);
System.out.println("Smallest: " + min);
}
}
答案 5 :(得分：0)
public class Grades
{
public static void main(String[] args) {
int score = 0; // Exam score
int min = 100; // Hold smallest score
int max = 0; // Hold largest score
Scanner keyboard = new Scanner(System.in);
// Display general instructions.
int i = 1;
do {
System.out.println("Enter an integer, or -99 to quit: ");
score = keyboard.nextInt();
if (score > max) {
max = score;
}
if (score < min) {
min = score;
}
i++;
if (i > 5) {
break;
}
} while ((score != -99));
// Display the largest and smallest score.
System.out.println("Largest: " + max);
System.out.println("Smallest: " + min);
}
}