Question

我是Java的初学者，我必须使用这些方法addElement(), elementAt(), removeElement(), size()在java中实现向量，我不知道我是如何尝试首先编写addElement的代码而我得到的这个错误：

enter image description here

我真的需要帮助吗

以下是代码：

import java.util.Vector;

class Vectimplement {
    public static void main(String[] args) {
        Vector v = new Vector();
        v.add("element_1");
        v.add("element_2");
        v.add("element_3");
        v.addElement("New Element");
        System.out.println("Elements in Vector :");

        for(int i=0; i < v.size(); i++){
            System.out.println(v.get(i));
        }
    }
}

Answer 1

使用泛型来指定要放入集合中的对象类型。

Vector<String> v = new Vector<>();

Answer 2

在压制警告后，我能够成功运行程序：

package test;

import java.util.Vector;

class Vectimplement {

@SuppressWarnings("unchecked")
public static void main(String[] args) {
    @SuppressWarnings("rawtypes")
    Vector v = new Vector();
    v.add("element_1");
    v.add("element_2");
    v.add("element_3");
    v.addElement("New Element");
    System.out.println("Elements in Vector :");
    for (int i = 0; i < v.size(); i++) {
        System.out.println(v.get(i));
    }
}
}

控制台输出：

element_1
element_2
element_3
New Element

生成这些警告是因为在Java6（或者可能是7）之后需要明确提供要存储在容器中的对象的“类型”。因此，最佳做法是使用：

Vector<String> v = new Vector<>();

Answer 3

Vector is a pre define class you can use it's method my creating it's object as follow,

To add values in vector use object.add() methods,

following are some methos:

public class Vectorexapp {
     public static void main(String[] args) {
        Vector v=new Vector();
        v.add(10);
        v.add(20);
        v.add("HELLO");
        v.add(40.5);

        System.out.println("first element:"+v.firstElement());

        System.out.println("last element:"+v.lastElement());

        System.out.println("Values of vector:"+v);
    }

}

Answer 4

Vector to add element at specified position:

public class Vectorexapp {
     public static void main(String[] args) {
        Vector v=new Vector();
        v.add(0,10);
        v.add(1,20);
        v.add(2,"HELLO");
        v.add(3,40.5);

        System.out.println("Value at index 2:" +v.get(1));
        System.out.println("Values of vector:"+v);
        v.clear();
         System.out.println("After clear vector values:"+v);
    }

}

output:
Value at index 2:20
Values of vector:[10, 20, HELLO, 40.5]
After clear vector values:[]

Answer 5

You can add values by accepting it from user:
public class Vectorexapp {
     public static void main(String[] args) {
         Scanner sc=new Scanner(System.in);
         int a,b;
         String s;
         double c;
         System.out.println("Enter 2 integer values, 1 string and 1 float value:");
         a=sc.nextInt();
         b=sc.nextInt();
         s=sc.next();
         c=sc.nextDouble();

        Vector v=new Vector();
        v.add(0,a);
        v.add(1,b);
        v.add(2,s);
        v.add(3,c);
        System.out.println("vector values:"+v);
         System.out.println("vector size:"+v.size());
         System.out.println("Vector capacity:"+v.capacity());

    }

}

output:
Enter 2 integer values, 1 string and 1 float value:
60
40
abcd
50.6
vector values:[60, 40, abcd, 50.6]
vector size:4
Vector capacity:10

程序在java中实现向量

5 个答案: