如何通过姓名或科目来储存、删除数据，并最终按照科目来列出所有数据
package lab6;
import java.util.ArrayList;
import java.util.Scanner;
public class Manager {
public static Scanner scanner = new Scanner(System.in);
public static ArrayList students = new ArrayList<>();
public static void main(String[] args) {
while (true) {
System.out.println("----------Gradebook-----------");
System.out.println("--【1】Record student scores---");
System.out.println("--【2】Delete student scores---");
System.out.println("--【3】Search by the subject---");
Student student = new Student();
System.out.println("Enter your choice");
String choice = scanner.next();
switch (choice) {
case "1":
student.addScore(students);
break;
case "2":
student.deleteStudent(students);
break;
case "3":
student.subject(students);
default:
break;
}
}
}
}
package lab6;
import java.util.ArrayList;
import java.util.Scanner;
public class Student {
public static Scanner scanner = new Scanner(System.in);
private String name;
private float math;
private float english;
public Student() {
}
public Student(String name, float math, float english ) {
this.name = name;
this.math = math;
this.english = english;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public float getMath() {
return math;
}
public void setMath(float math) {
this.math = math;
}
public float getEnglish() {
return english;
}
public void setEnglish(float english) {
this.english = english;
}
public void addScore(ArrayList students) {
System.out.println("--Record student scores---");
System.out.println("Please enter the following data in sequence:");
String name;
while (true) {
System.out.println("name");
name = scanner.next();
break;
}
System.out.println("Math");
float math = scanner.nextFloat();
System.out.println("English");
float english = scanner.nextFloat();
Student student = new Student();
student.setName(name);
student.setMath(math);
student.setEnglish(english);
students.add(student);
System.out.println("Adding succeeded");
}
public void deleteStudent(ArrayList students) {
System.out.println("--Delete student scores---");
System.out.println("Enter the name of the student whose grade you want to delete");
String name = scanner.next();
int index = -1;
for (int i = 0; i < students.size(); i++) {
Student student = students.get(i);
if (student.getName() == name) {
index = i;
break;
}
}
students.remove(index);
System.out.println("--Successfully deleted---");
}
public void subject(ArrayList students) {
System.out.println("--Search by the subject---");
System.out.println("Please enter the subject you want to find");
}
}
Exception in thread "main" java.lang.IndexOutOfBoundsException: Index -1 out of bounds for length 0
at java.base/jdk.internal.util.Preconditions.outOfBounds(Preconditions.java:64)
at java.base/jdk.internal.util.Preconditions.outOfBoundsCheckIndex(Preconditions.java:70)
at java.base/jdk.internal.util.Preconditions.checkIndex(Preconditions.java:266)
at java.base/java.util.Objects.checkIndex(Objects.java:359)
at java.base/java.util.ArrayList.remove(ArrayList.java:504)
at lab6/lab6.Student.deleteStudent(Student.java:89)
at lab6/lab6.Manager.main(Manager.java:25)
1.根据姓名添加成绩
2.按学生姓名和科目名称删除成绩
3.按照科目名称查询成绩，要能看到所有学生这一科的成绩
报错是数组越界问题。
if (student.getName() == name) 字符串的比较用equals方法
首先你看看debug一下你看看我看两个名字相同的时候能不能进入你的判断里并进行赋值，之后你看看如果你判断这个条件不成立那index=-1直接到你的remove那会不会出错？
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