Question

我想知道为什么我的矢量会重复？我知道我可以使用ArrayList，但这是我的黑莓应用程序的测试，目前只使用向量。这是我继续得到的结果：

ID:3 and Name:Catty and Price:100 and Msg:Catty is a preety girl
ID:3 and Name:Catty and Price:100 and Msg:Catty is a preety girl
ID:3 and Name:Catty and Price:100 and Msg:Catty is a preety girl

以下是代码 testapp.java

package testing;

import java.util.Vector;


public class testapp {
    private static Vector<String> listElements= new Vector<String>();
    private static Vector<String> listName= new Vector<String>();
    private static Vector<Integer> listPrice= new Vector<Integer>();
    private static Vector<String> listDate= new Vector<String>();
    private static Vector<String> listAbstract= new Vector<String>();
    private static Vector<rec> a = new Vector<rec>();
    static rec record = new rec();

    public static void main(String[] args){

        vectorBuilder();
        recordBuilder();
        showElements();

    }

    public static void recordBuilder(){

        try{
            for(int i=0;i<listElements.size();i++){
                record.setId((String) listElements.elementAt(i));
                record.setName((String) listName.elementAt(i));
                record.setDate((String) listDate.elementAt(i));
                record.setPrice(((Integer) listPrice.elementAt(i)).intValue());
                record.setAbstract((String) listAbstract.elementAt(i));
                a.addElement(record);   
            }

        }catch (Exception e){
            System.out.println("Record Builder Error: " + e.getMessage());
        }
    }

    public static void vectorBuilder(){
        //Ben
        listElements.addElement("1");
        listName.addElement("Ben");
        listPrice.addElement(502);
        listDate.addElement("2012-05-12");
        listAbstract.addElement("Ben is a Good Boy");

        //Kesha
        listElements.addElement("2");
        listName.addElement("Kesha");
        listPrice.addElement(367);
        listDate.addElement("2012-02-24");
        listAbstract.addElement("Kesha Works hard in her school work");

        //Catty
        listElements.addElement("3");
        listName.addElement("Catty");
        listPrice.addElement(100);
        listDate.addElement("2012-01-04");
        listAbstract.addElement("Catty is a preety girl");


    }

    public static void showElements(){
        for(int i=0;i<a.size();i++)
        {
            rec r = (rec) a.elementAt(i);
            System.out.println("ID:"+r.getId()+" and Name:"+r.getName()+" and Price:"+r.getPrice()+" and Msg:"+r.getAbstract());
        }

    }
}

这是 rec.java

package testing;


public class rec {
        String name;
        String id;
        String date;
        String strAbstract;
        int price;


        public String getName() {
            return name;
        }
        public void setName(String name) {
            this.name = name;
        }
        public String getId() {
            return id;
        }
        public void setId(String id) {
            this.id = id;
        }

        public String getDate() {
            return date;
        }
        public void setDate(String date) {
            this.date = date;
        }

        public String getAbstract() {
            return strAbstract;
        }
        public void setAbstract(String strAbstract) {
            this.strAbstract = strAbstract;
        }

        public int getPrice() {
            return price;
        }
        public void setPrice(int price) {
            this.price = price;
        }


}

Answer 1

您需要在调用recordBuilder时创建新的rec。如果您不创建新record，则会更新相同的实例，这就是您获得重复项的原因。

for(int i=0;i<listElements.size();i++){
                rec record = new rec();
                record.setId((String) listElements.elementAt(i));
                record.setName((String) listName.elementAt(i));
                record.setDate((String) listDate.elementAt(i));
                record.setPrice(((Integer) listPrice.elementAt(i)).intValue());
                record.setAbstract((String) listAbstract.elementAt(i));
                a.addElement(record);   
            }

注意：Java命名约定建议类名以大写字母开头。 Record可能比rec好名。

为什么我的矢量会重复？

1 个答案: