并发修改异常在遍历的ArrayList [英] Concurrent modification Exception while iterating over ArrayList
问题描述
在并发修改错误的排序方法,结果当我使用TEMP = iterator.next()。你可以帮我解决并发修改错误。
我给了code为整个类,但我只是想完成排序方法。在此先感谢您的帮助。
我要所有的ArrayList中的数组进行排序。
包HashSet的; 进口的java.io.InputStream;
进口的java.util.ArrayList;
进口java.util.Collections中;
进口java.util.ListIterator中;
进口java.util.Scanner中; 公共类电话簿{
INT容量= 10;
私人的ArrayList< PhoneBookEntry> []桶; 公用电话簿(){
这(10);
加载();
} 公用电话簿(INT大小){
容量=大小;
水桶=新的ArrayList【尺寸】;
的for(int i = 0; I< buckets.length;我++)
桶[I] =新的ArrayList< PhoneBookEntry>();
} 公众诠释的getSize(){
INT TOT = 0;
对于(ArrayList的< PhoneBookEntry> X:桶)
TOT + = x.size();
返回TOT;
} 公共布尔加(PhoneBookEntry进入){
如果(包含(入门))
返回false;
INT X = Math.abs(entry.hash code());
水桶[X%buckets.length]。新增(输入);
返回true;
} 公共无效负载(){
InputStream为=的getClass()。getClassLoader()。的getResourceAsStream(
phone.txt);
扫描程序扫描=新的扫描仪(是);
而(scan.hasNext())
添加(新PhoneBookEntry(scan.next(),scan.nextInt()));
scan.close();
} 公共无效bucketSize(){
的for(int i = 0; I< buckets.length;我++)
的System.out.println(ⅰ++水桶[I] .size());
} 公共布尔包含(PhoneBookEntry字){
INT X = Math.abs(word.hash code());
返回水桶[X%buckets.length]。载有(字);
} 公众诠释getCapacity(){
返回能力;
} 公众诠释getLongestList(){
INT麻木= 0;
对于(ArrayList的< PhoneBookEntry> X:桶)
如果(x.size()>麻木)
麻木= x.size();
返回麻木;
} 公共无效显示(){
对于(ArrayList的< PhoneBookEntry> X:桶)
的System.out.println(X);
} 公众诠释getNumberOfNulls(){
INT麻木= 0;
对于(ArrayList的< PhoneBookEntry> X:桶)
如果(x.size()== 0)
麻木++;
返回麻木;
} 公共字符串查找(字符串名称){
字符串麻木=名称+的数量未找到;
对于(ArrayList的< PhoneBookEntry> X:桶)
的for(int i = 0; I< x.size();我++)
如果(x.get(ⅰ).getN()。等于(名))
麻木=名称+的+号是+ x.get(I).getNr();
返回麻木;
} 公众诠释internalLookUp(字符串名称){
INT麻木= 0;
对于(ArrayList的< PhoneBookEntry> X:桶)
的for(int i = 0; I< x.size();我++)
如果(x.get(ⅰ).getN()。等于(名))
麻木= x.get(I).getNr();
返回麻木;
} 公共无效的sort(){
字符串TEMP =;
ArrayList的<串GT;名单=新的ArrayList<串GT;();
&的ListIterator LT;弦乐>迭代= list.listIterator();
最终的ArrayList< PhoneBookEntry> []数据= buckets.clone();
对于(ArrayList的< PhoneBookEntry> X:桶){
的for(int i = 0; I< x.size();我++){
list.add(x.get(ⅰ).getN());
}
Collections.sort(名单);
对于(INT B = 0; B< x.size(); B ++){
TEMP = iterator.next(); //错误行
x.get(二).setN(临时);
x.get(二).setNr(internalLookUp(临时));
}
}
} 公共静态无效的主要(字串[] args){
电话簿手机=新的电话簿();
phone.display();
的System.out.println();
的System.out.println(容量为+ phone.getCapacity());
的System.out.println();
的System.out.println(大小+ phone.getSize());
的System.out.println();
的System.out.println(获取最长的名单+ phone.getLongestList());
的System.out.println();
的System.out.println(空值的数量+ phone.getNumberOfNulls());
的System.out.println();
的System.out.println(phone.lookup(鱼));
phone.sort();
}
}
它看起来像你的问题是,你创建一个迭代器列表,然后修改列表(添加+排序),然后尝试使用迭代器。
如果您不是在这之后创建的迭代器,它应该工作。
如。
为(ArrayList的< PhoneBookEntry> X:桶){
的for(int i = 0; I< x.size();我++){
list.add(x.get(ⅰ).getN());
}
Collections.sort(名单);
&的ListIterator LT;弦乐>迭代= list.listIterator(); //创建的Iterator这里
对于(INT B = 0; B< x.size(); B ++){
TEMP = iterator.next(); //错误行
x.get(二).setN(临时);
x.get(二).setNr(internalLookUp(临时));
}
The sort method results in a concurrent modification error when i use temp = iterator.next(). Can you please help me resolve the concurrent modification error. I gave the code for the entire class but I'm only trying complete the sort method. Thanks in advance for your help.
I have to sort all the the arrays in the arraylist.
package HashSet;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Collections;
import java.util.ListIterator;
import java.util.Scanner;
public class PhoneBook {
int capacity = 10;
private ArrayList<PhoneBookEntry>[] buckets;
public PhoneBook() {
this(10);
load();
}
public PhoneBook(int size) {
capacity = size;
buckets = new ArrayList[size];
for (int i = 0; i < buckets.length; i++)
buckets[i] = new ArrayList<PhoneBookEntry>();
}
public int getSize() {
int tot = 0;
for (ArrayList<PhoneBookEntry> x : buckets)
tot += x.size();
return tot;
}
public boolean add(PhoneBookEntry entry) {
if (contains(entry))
return false;
int x = Math.abs(entry.hashCode());
buckets[x % buckets.length].add(entry);
return true;
}
public void load() {
InputStream is = getClass().getClassLoader().getResourceAsStream(
"phone.txt");
Scanner scan = new Scanner(is);
while (scan.hasNext())
add(new PhoneBookEntry(scan.next(), scan.nextInt()));
scan.close();
}
public void bucketSize() {
for (int i = 0; i < buckets.length; i++)
System.out.println(i + " " + buckets[i].size());
}
public boolean contains(PhoneBookEntry word) {
int x = Math.abs(word.hashCode());
return buckets[x % buckets.length].contains(word);
}
public int getCapacity() {
return capacity;
}
public int getLongestList() {
int numb = 0;
for (ArrayList<PhoneBookEntry> x : buckets)
if (x.size() > numb)
numb = x.size();
return numb;
}
public void display() {
for (ArrayList<PhoneBookEntry> x : buckets)
System.out.println(x);
}
public int getNumberOfNulls() {
int numb = 0;
for (ArrayList<PhoneBookEntry> x : buckets)
if (x.size() == 0)
numb++;
return numb;
}
public String lookup(String name) {
String numb = name + "'s number not found";
for (ArrayList<PhoneBookEntry> x : buckets)
for (int i = 0; i < x.size(); i++)
if (x.get(i).getN().equals(name))
numb = name + "'s" + " number is " + x.get(i).getNr();
return numb;
}
public int internalLookUp(String name) {
int numb = 0;
for (ArrayList<PhoneBookEntry> x : buckets)
for (int i = 0; i < x.size(); i++)
if (x.get(i).getN().equals(name))
numb = x.get(i).getNr();
return numb;
}
public void sort() {
String temp = "";
ArrayList<String> list = new ArrayList<String>();
ListIterator<String> iterator = list.listIterator();
final ArrayList<PhoneBookEntry>[] data = buckets.clone();
for (ArrayList<PhoneBookEntry> x : buckets) {
for (int i = 0; i < x.size(); i++) {
list.add(x.get(i).getN());
}
Collections.sort(list);
for (int b = 0; b < x.size(); b++) {
temp = iterator.next(); //error line
x.get(b).setN(temp);
x.get(b).setNr(internalLookUp(temp));
}
}
}
public static void main(String[] args) {
PhoneBook phone = new PhoneBook();
phone.display();
System.out.println();
System.out.println("Capacity is " + phone.getCapacity());
System.out.println();
System.out.println("Size is " + phone.getSize());
System.out.println();
System.out.println("Get longest list " + phone.getLongestList());
System.out.println();
System.out.println("Number of Nulls " + phone.getNumberOfNulls());
System.out.println();
System.out.println(phone.lookup("Fish"));
phone.sort();
}
}
It looks like your problem is that you're creating an iterator for a list, then modifying the list (adding + sorting), then attempting to use the iterator.
If you instead created the iterator after this, it should work.
eg.
for (ArrayList<PhoneBookEntry> x : buckets) {
for (int i = 0; i < x.size(); i++) {
list.add(x.get(i).getN());
}
Collections.sort(list);
ListIterator<String> iterator = list.listIterator(); // Iterator created here
for (int b = 0; b < x.size(); b++) {
temp = iterator.next(); //error line
x.get(b).setN(temp);
x.get(b).setNr(internalLookUp(temp));
}
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