如何从java中的链表中删除一个对象？ [英] how to remove a object from linked list in java?

问题描述

我的代码有一个问题，我做了一个示例程序来显示从一个链表的emp细节，现在的问题，当我试图删除一个特定的条目意味着它不工作，我希望我做了一些错误在我的代码中，你可以建议怎么做？

  import java.util。*; 
 
 class EmpDedup {
 int record; 
 String fprint; 
 int fid; 
 
 EmpDedup（int record，String fprint，int fid）{
 this.record = record; 
 this.fprint = fprint; 
 this.fid = fid; 
} 
 
 public int getRecord（）{
 return record; 
} 
 
 public String getFprint（）{
 return fprint; 
} 
 
 public int getFid（）{
 return fid; 
} 
 
 public static void main（String [] args）{
 int count = 0; 
 LinkedList&EmpDedup> list = new LinkedList&EmpDedup>（）; 
 list.add（new EmpDedup（101，entry1，20））; 
 list.add（new EmpDedup（102，entry2，30））; 
 list.add（new EmpDedup（103，entry3，40））; 
 list.add（new EmpDedup（104，entry4，50））; 
 
扫描仪输入=新的扫描仪（System.in）; 
 System.out.print（输入记录不显示）; 
 int rec = input.nextInt（）; 
 for（EmpDedup data：list）{
 if（data.getRecord（）== rec）{
 System.out.println（data.getRecord（）+\t+ data.getFprint（）+\t+ data.getFid（）+\t）; 
 
 count ++; 
 
} 
} 
 System.out.println（链接的大小是：\t+ list.size（））; 
 
 System.out.println（可用记录数为：+ count）; 
 
 System.out.println（链接的大小是：\t+ list.size（））; 
扫描仪input1 =新的扫描仪（System.in）; 
 System.out.print（输入记录no to delete：）; //这里我尝试删除一个特定的记录
 int rec1 = input1.nextInt（）; 
 for（EmpDedup data：list）{
 if（data.getRecord（）== rec1）{
 // System.out.println（data.getRecord（）+\t + data.getFprint（）+\t+ data.getFid（）+\t）; 
 list.remove（data）; //问题在这里
 count ++; 
 
} 
} 
} 
} 
  

解决方案

您不能在列表中添加（添加，删除...项目）。您必须使用Iterator

 （Iterator& EmpDedup> iter = list.iterator（）; iter.hasNext（）; ）{
 EmpDedup data = iter.next（）; 
 if（data.getRecord（）== rec1）{
 iter.remove（）; 
} 
} 
  

请参阅 http://docs.oracle.com/javase/6/docs/api/java/util/Iterator .html

i have one problem with my code ,i did a sample program to display the emp details from a linked list,now the problem when i trying to delete a particular entry means it doesn't work,i hope i did some mistake in my code could you suggest how to do that?

import java.util.*;

class EmpDedup {
    int record;
    String fprint;
    int fid;

    EmpDedup(int record, String fprint, int fid) {
        this.record = record;
        this.fprint = fprint;
        this.fid = fid;
    }

    public int getRecord() {
        return record;
    }

    public String getFprint() {
        return fprint;
    }

    public int getFid() {
        return fid;
    }

    public static void main(String[] args) {
        int count = 0;
        LinkedList<EmpDedup> list = new LinkedList<EmpDedup>();
        list.add(new EmpDedup(101, "entry1", 20));
        list.add(new EmpDedup(102, "entry2", 30));
        list.add(new EmpDedup(103, "entry3", 40));
        list.add(new EmpDedup(104, "entry4", 50));

        Scanner input = new Scanner(System.in);
        System.out.print("Enter record no to display: ");
        int rec = input.nextInt();
        for (EmpDedup data : list) {
            if (data.getRecord() == rec) {
                System.out.println(data.getRecord() + "\t" + data.getFprint() + "\t" + data.getFid() + "\t");

                count++;

            }
        }
        System.out.println("The size of an linkedlist is: \t" + list.size());

        System.out.println("The number of  available record  is :" + count);

        System.out.println("The size of an linkedlist is: \t" + list.size());
        Scanner input1 = new Scanner(System.in);
        System.out.print("Enter record no to delete: ");// here i try to delete a particular record
        int rec1 = input1.nextInt();
        for (EmpDedup data : list) {
            if (data.getRecord() == rec1) {
                // System.out.println(data.getRecord()+"\t"+data.getFprint()+"\t"+data.getFid()+"\t");
                list.remove(data); // problem is here
                count++;

            }
        }
    }
}

解决方案

you cannot operate in lists (add, remove... items) while you iterate on them. You have to use an Iterator

for(Iterator<EmpDedup> iter = list.iterator(); iter.hasNext();) {
    EmpDedup data = iter.next();
    if (data.getRecord() == rec1) {
        iter.remove();
    }
}

see http://docs.oracle.com/javase/6/docs/api/java/util/Iterator.html

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