[英]Accepting input through an array in Java
我正在尝试让用户输入数字数组(=学生的分数)。 同样,用户自己将决定数组的大小,即班上的学生人数。 接受了每个学生的分数后,我想将它们存储在一个数组中,显示所有学生的分数,并计算班级的平均值。 稍后会达到平均水平。 有人可以帮我解决这段(显然是错误的)代码,谢谢!
package chapter2.Arrays;
import java.util.*;
public class Arrays_ExampleOne {
static int size;
static int marks;
static int [] numbers=new int [size];
static Scanner in=new Scanner(System.in);
public static void main(String[] args) {
// TODO Auto-generated method stub
System.out.println("Welcome to Cincinnati Elementary");
System.out.println("Class report details for ");
System.out.println("Enter the number of students in the class");
size=in.nextInt();
System.out.println("Enter the marks of each student");
for(int i=0;i<=size;i++)
{
numbers[i]=in.nextInt();
}
/* System.out.println("The marks of all students are"+ " ");
{
for(int i=0;i<=size;i++)
{
System.out.print(numbers[i]);
}
System.out.println();
}
//int avg=
*/}
}
================================================== =========
修改后的代码,希望在main之外创建一个函数以计算数组的平均值:
package chapter2.Arrays;
import java.util.*;
public class Arrays_ExampleOne {
/*static int size;
static int marks;
static int [] numbers=new int [size];*/
static Scanner in=new Scanner(System.in);
public static void main(String[] args) {
// TODO Auto-generated method stub
System.out.println("Welcome to Cincinnati Elementary");
System.out.println("Class report details for ");
System.out.println("Enter the number of students in the class");
int size;
//static int marks;
//static int [] numbers=new int [size];
size=in.nextInt();
int [] numbers=new int [size];
System.out.println("Enter the marks of each student");
for(int i=0;i<size;i++)
{
numbers[i]=in.nextInt();
}
System.out.println("The marks of all students are:"+ " ");
{
for(int temp:numbers)
{
System.out.print(temp+ " ");
}
System.out.println();
}
int arraySize=numbers.length;
int arraySum=0;
//Calculate the sum of array elements
for(int temp1:numbers)
{
arraySum+=temp1;
}
int average=arraySum/arraySize;
System.out.println("The average of all the students scores is:"+ " "+average);
}
/*public int calculateAverage(int array[])
{
int arraySize=array.length;
}*/
}
================================================== =============在main之外添加了用于计算平均值的单独代码。
package chapter2.Arrays;
import java.util.*;
public class Arrays_ExampleOne {
/*static int size;
static int marks;
static int [] numbers=new int [size];*/
static Scanner in=new Scanner(System.in);
public static void main(String[] args) {
// TODO Auto-generated method stub
Arrays_ExampleOne obj=new Arrays_ExampleOne();
System.out.println("Welcome to Cincinnati Elementary");
System.out.println("Class report details for ");
System.out.println("Enter the number of students in the class");
int size;
//static int marks;
//static int [] numbers=new int [size];
size=in.nextInt();
int [] numbers=new int [size];
System.out.println("Enter the marks of each student");
for(int i=0;i<size;i++)
{
numbers[i]=in.nextInt();
}
System.out.println("The marks of all students are:"+ " ");
{
for(int temp:numbers)
{
System.out.print(temp+ " ");
}
System.out.println();
}
/* int arraySize=numbers.length;
int arraySum=0;
//Calculate the sum of array elements
for(int temp1:numbers)
{
arraySum+=temp1;
}
int average=arraySum/arraySize;
System.out.println("The average of all the students scores is:"+ " "+average);*/
int average=obj.calculateAverage(numbers);
System.out.println("The average of all the students is:"+ " "+average);
}
public int calculateAverage(int array[])
{
int arraySize=array.length;
int arraySum=0;
for(int temp: array)
{
arraySum+=temp;
}
int average=arraySum/arraySize;
return average;
}
}
首先,应先要求用户输入大小,然后设置数组大小:
static int size;
static int marks;
static Scanner in=new Scanner(System.in);
public static void main(String[] args) {
System.out.println("Enter number of student:");
size = in.nextInt();
int [] numbers=new int [size];
//the rest of your code goes here
}
注意:请注意您的for循环:
for(int i=0;i<=size;i++){
^
numbers[i]=in.nextInt();
}
这将导致ArrayIndexOutOfBoundException
,因为你想在索引访问元素size
,其最大index
有n大小的数组为n-1。 应该是 <
而不是<=
对于方法calculateAverage,它应如下所示:
public static double calculateAverage(int array[])
{
double sum=0.0;
for(int i=0;i<array.length;i++){
sum+=array[i];
}
return sum / array.length;
}
请注意,此方法应该是静态的,因为您想在静态方法中使用它,并且average始终处理double
/ float
数据类型,而不是int
在main方法中,您可以这样调用它:
System.out.println("Average marks:"+calculateAverage(numbers));
static int size;
static int marks;
static int [] numbers=new int [size];
创建数组时, size
仍为默认值零。 在这里,您总是以长度为零的数组结尾。
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