特别是构建 每个垂直列的总 &是一项荒谬的任务。在屏幕上显示。虽然,计算水平行的总数似乎永远不是一个挑战。
我遇到的问题有三个问题。
如何
calculate
每个垂直列的总数?索引(
id
)按降序打印。如何按升序打印?- 醇>
此外,在百分比列中,小数点后面的值被丢弃。如何显示?例如..如果
answer
应该是 78.25%,它表现为 78.0%P.S: (小数点后2位是我的目标。)
POJO课程 - StudentsProg.java
package com.students.marks;
import java.util.Arrays;
public class StudentsProg {
private int id = 0;
private String name;
private int english;
private int german;
private int french;
private int arabic;
private double percentage;
private int total_marks;
private int rowHighest;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getEnglish() {
return english;
}
public void setEnglish(int english) {
this.english = english;
}
public int getGerman() {
return german;
}
public void setGerman(int german) {
this.german = german;
}
public int getFrench() {
return french;
}
public void setFrench(int french) {
this.french = french;
}
public int getArabic() {
return arabic;
}
public void setArabic(int arabic) {
this.arabic = arabic;
}
public double getPercentage() {
return percentage;
}
public void setPercentage(double percentage) {
this.percentage = percentage;
}
public int getTotal_marks() {
return total_marks;
}
public void setTotal_marks(int total_marks) {
this.total_marks = total_marks;
}
public int getRowHighest() {
return rowHighest;
}
public void setRowHighest(int rowHighest) {
this.rowHighest = rowHighest;
}
public String toString() {
id = id+1;
return (id + "\t" +name+ "\t\t" +english+ "\t" + " " +german+ "\t" + " "+ french+ "\t" + " " +arabic+ "\t" +" " +total_marks+ "\t\t" + " " +percentage+ "\t\t" +rowHighest);
}
}
StudentsProgMain.java
import java.util.Scanner;
public class StudentsProgMain {
@SuppressWarnings("resource")
public static void main(String[] args) {
int count = 0;
StudentsProg[] stud = new StudentsProg[15];
int choice=0;
int max = 0;
Scanner scanner = new Scanner(System.in);
do{
System.out.println("1: Add new Student");
System.out.println("2: List Student");
System.out.println("3: List Student By Name.");
System.out.println("4: Delete Student");
System.out.println("5: Exit");
System.out.println("Please enter your choice \n\n");
choice=scanner.nextInt();
switch(choice){
case 1:
stud[count] = new StudentsProg();
System.out.println("Enter student name");
stud[count].setName(scanner.next());
System.out.println("Enter marks in English");
stud[count].setEnglish(scanner.nextInt());
System.out.println("Enter marks in German");
stud[count].setGerman(scanner.nextInt());
System.out.println("Enter marks in French");
stud[count].setFrench(scanner.nextInt());
System.out.println("Enter marks in Arabic");
stud[count].setArabic(scanner.nextInt());
count++;
break;
case 2:
System.out.println("ID\t" + "Name \t\t\t" + "English\t" + " " + "German\t"+ " " + "French\t" + " " + "Arabic\t"
+" "+ "Total Marks\t" + " " + "Percentage\t" + "Highest Marks(Row)\n" +
"------------------------------------------------------------------------"
+ "------------------------------------------- \n ");
for(int i=0; i<count; i++){
if(stud[i]!=null){
int total_marks = stud[i].getEnglish()+stud[i].getGerman()+ stud[i].getFrench()+stud[i].getArabic();
stud[i].setTotal_marks(total_marks);
double calc_per = ((total_marks*100)/400);
stud[i].setPercentage(calc_per);
int arrayListMarks [] = {stud[i].getEnglish(), stud[i].getFrench(), stud[i].getGerman(), stud[i].getArabic()};
max = arrayListMarks[0];
for (int j = 1; j < arrayListMarks.length; j++) {
if(arrayListMarks[j] > max)
max = arrayListMarks[j]; }
stud[i].setRowHighest(max);
System.out.println(stud[i].toString());
System.out.println("\n");}
}
System.out.println("--------------------------------------------------------------"
+ "----------------------------------------------------- \n");
System.out.println("\tTotal :" +"\n");
break;
case 3 :
System.out.println("Please enter your name");
String name = scanner.next();
System.out.println("\n" + "ID\t" + "Name \t\t\t" + "English\t" + " " + "German\t"+ " " + "French\t" + " " + "Arabic\t"
+" "+ "Total Marks\t" + " " + "Percentage\t" + "Highest Marks(Row)\n" +
"------------------------------------------------------------------------"
+ "------------------------------------------- \n ");
for(int i =0 ; i<count; i++){
if(stud[i]!=null && stud[i].getName().equals(name))
System.out.println(stud[i].toString()); }
System.out.println("--------------------------------------------------------------"
+ "----------------------------------------------------- \n");
break;
case 4 :
System.out.println("Please enter your name");
String naam = scanner.next();
for (int i = 0; i<count; i++) {
if(stud[i]!=null && stud[i].getName()==naam)
stud[i]=null;
}
break;
case 5:
System.exit(0);
System.out.println("You have exited successfully");
default :
System.out.println("Invalid choice");
}
}while(true);
}
}
答案 0 :(得分:1)
百分比计算的问题是代码行double calc_per = ((total_marks*100)/400);
将执行整数运算并将每个中间结果截断为整数。要解决此问题,您需要在计算中的某处包含浮点数,方法是将total_marks转换为double,如下所示:
double calc_per = ((Integer.valueOf(total_marks).doubleValue()*100)/400);
或者像这样使用浮点常量:
double calc_per = ((total_marks*100.0)/400);
垂直总计应该只是将行值添加到打印循环内的变量。
我不太确定你的索引顺序问题但是toString()中的代码读取id = id+1;
看起来不对。每次调用toString()时,这都会增加Id。而不是那样,您的创建代码应该在创建对象之后设置id的值,如:
stud[count] = new StudentsProg();
// add the following line of code.
stud[count].setId(count);
System.out.println("Enter student name");
stud[count].setName(scanner.next());