Question

JAVA vector 的查询与删除

import java.io.*;
import java.util.*;
public class Student
{
public static final Vector vector = new Vector(10,5);
public Student()
{

}
public static void main(String[] args)
{
menu();

int tag=10;
new Student();
while(true)
{
String s=readInput();
tag=Integer.parseInt(s);
switch(tag)
{
case 1:
{
query();
};break;
case 2:
{
add();

};break;
case 3:
{
delete();
};break;
case 4:
{
viewAll();
};break;
case 5:
{
System.exit(0);
};break;

}
}

}

public static String readInput()
{
try
{
BufferedReader in=new BufferedReader(new InputStreamReader(System.in));
return in.readLine();
}
catch(IOException e){}
return "";
}
public static void query()
{
System.out.println("please input the student's ID.:");
}
public static void add()
{
}
public static void delete()
{
System.out.println("\t input the ID you want to delete:");
String i=readInput();
}
public static void viewAll()
{

vector.add(new Student1("001","a.mo",90,89));
vector.add(new Student1("002","b.mo",90,47));
vector.add(new Student1("003","c.mo",99,56));
for(int i=0;i<vector.size();i++)
{
Student1 student = (Student1)vector.get(i);
System.out.println("\tID:"+student.getId());
System.out.println("\tname:"+student.getName());
System.out.println("\tMath:"+student.getScore());
System.out.println("\tEnglish:"+student.getScore1()+"\n");

}

menu();

}
public static void menu()
{
System.out.println("\t welcome to my student's score system!");
System.out.println("\t*********************************************");
System.out.println("\t************* 1.Query ****************");
System.out.println("\t************* 2.Add ****************");
System.out.println("\t************* 3.Delete ****************");
System.out.println("\t************* 4.View All ****************");
System.out.println("\t************* 5.Exit ****************");
System.out.println("\t*********************************************");
}

}
class Student1
{
private String id;
private String name;
private float score;
private float score1;

public Student1(String id,String name,float score,float score1)
{
this.name = name;
this.id = id;
this.score = score;
this.score1 = score1;
}
public String getId()
{
return id;
}
public String getName()
{
return name;
}
public float getScore()
{
return score;
}
public float getScore1()
{
return score1;
}
public void setId(String id)
{
this.id = id;
}
public void setName(String name)
{
this.name = name;
}
public void setScore(float score)
{
this.score = score;
}
public void setScore1(float score1)
{
this.score = score1;
}
}该程序，如何实现？
System.out.println("please input the student's math's score.:");
String s=readInput();
float s2=Float.parseFloat(s);
for(int i=0;i<vector.size();i++)
{
Student1 student = (Student1)vector.get(i);
if(s2==student.getScore())
{
vector.removeElementAt(i) ;
System.out.println("Delete success!");
}
else
System.out.println("cannot find !");
请告诉我为什么会这样子，谢谢了。现在查找与删除就这个STRING类型不能匹配了。

Answer 1

1、你这程序对vector不会有任何改动，因为vector的声明里面说的非常明白了：fianl，禁止任何形式的改动，所以，你查看可以、取值可以，但是删除添加等操作绝对不可能完成。

2、Vector中的每个单独数据都是一个Element，你可以在里面存任何类型的数据：字符串、int数值、byte数值、图片、graphics画笔、数组、Vector以及各种自定义类等等都可以。removeElement（）就是移除这些你存进来的数据对象，参数是需要移除的数据，Vector会查找符合形参的元素，然后将它删除，如果找不到不进行任何操作；如果想输入一个数字删除一个元素，那么应该使用removeElementAt（int index）这个方法，将指定索引位置index处的数据删除，不管他是什么。

3、修改后的程序如下：
import java.io.*;
import java.util.*;
import javax.swing.JList ;

mport java.io.*;
import java.util.*;
public class Student
{
public static Vector vector = new Vector(10,5);
public Student()
{}

public static void main(String[] args)
{
menu();

int tag=10;
new Student();
while(true)
{
String s=readInput();
tag=Integer.parseInt(s);
switch(tag)
{
case 1:
{
query();
};break;
case 2:
{
add();

};break;
case 3:
{
delete();
};break;
case 4:
{
viewAll();
};break;
case 5:
{
System.exit(0);
};break;

}
}

}

public static String readInput()
{
try
{
BufferedReader in=new BufferedReader(new InputStreamReader(System.in));
return in.readLine();
}
catch(IOException e){}
return "";
}
public static void query()
{
JList list = new JList(vector) ;//list就是当前学生的列表了.

System.out.println("please input the student's ID.:");
}
public static void add()
{
Student1 student = new Student1("张三",0,80,80.5) ;
vector.addElement(student) ;
vector.add(new Student1("001","a.mo",90,89));
vector.add(new Student1("002","b.mo",90,47));
vector.add(new Student1("003","c.mo",99,56));

}
public static void delete()
{
System.out.println("\t input the ID you want to delete:");
String i=readInput();
int index = vector.indexOf(i) ;
if(index < 0 || index >= vector.size())
System.out.println("没有此数据!");

vector.removeElementAt(index) ;
}
public static void viewAll()
{
for(int i=0;i<vector.size();i++)
{
Student1 student = (Student1)vector.elementAt(i);
System.out.println("\tID:"+student.getId());
System.out.println("\tname:"+student.getName());
System.out.println("\tMath:"+student.getScore());
System.out.println("\tEnglish:"+student.getScore1()+"\n");

}

menu();

}
public static void menu()
{
System.out.println("\t welcome to my student's score system!");
System.out.println("\t*********************************************");
System.out.println("\t************* 1.Query ****************");
System.out.println("\t************* 2.Add ****************");
System.out.println("\t************* 3.Delete ****************");
System.out.println("\t************* 4.View All ****************");
System.out.println("\t************* 5.Exit ****************");
System.out.println("\t*********************************************");
}

}
class Student1
{
private String id;
private String name;
private float score;
private float score1;

public Student1(String id,String name,float score,float score1)
{
this.name = name;
this.id = id;
this.score = score;
this.score1 = score1;
}
public String getId()
{
return id;
}
public String getName()
{
return name;
}
public float getScore()
{
return score;
}
public float getScore1()
{
return score1;
}
public void setId(String id)
{
this.id = id;
}
public void setName(String name)
{
this.name = name;
}
public void setScore(float score)
{
this.score = score;
}
public void setScore1(float score1)
{
this.score = score1;
}

public String toString()
{
return "name = " + name + " , id = " + id + " , score = " + score + " , score1 = " + score1 ;
}

}

Answer 2

public static final Vector<student1> vector = new Vector()<student>;这样声明嘛，然后vector。addelement（new student1（？？？））；添加信息呗，查询就是for循环检查vector。elementAt（i）。id==（ID）；vector.removeElement()这个就是先用id查询到一个element然后vector.removeElement(vector。elementAt（i）)；就这样删除啦。

Answer 3

该程序，如何实现？
CPU执行2进制码实现！这个回答满意否？
－－－－－－－－－－－这样也才是完整的问题散

你去看下vector类，他是继承List的。他的removeElement()方法是按照你写入顺序，建议使用HashMap

Answer 4

该程序，如何实现？
CPU执行2进制码实现！这个回答满意否？
－－－－－－－－－－－这样也才是完整的问题散

Answer 5

程序可以编译运行,只是逻辑上欠考虑
做的不错