解决java.util.ConcurrentModificationException

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最新推荐文章于 2025-03-13 14:58:20 发布

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文章标签： ConcurrentModificationException 异常并发

本文链接：https://blog.youkuaiyun.com/qq_39150374/article/details/103366529

版权

本文深入探讨了Java中并发编程常见的ConcurrentModificationException异常，通过一个具体案例，详细分析了异常产生的原因，并提供了三种有效的解决方案，包括使用Vector、synchronizedList和CopyOnWriteArrayList。

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bug再现

F:\Java\jdk1.8.0_121\bin\java.exe "-javaagent:F:\JetBrains\IntelliJ IDEA 2018.1.6\lib\idea_rt.jar=63654:F:\JetBrains\IntelliJ IDEA 2018.1.6\bin" -Dfile.encoding=UTF-8 -classpath F:\Java\jdk1.8.0_121\jre\lib\charsets.jar;F:\Java\jdk1.8.0_121\jre\lib\deploy.jar;F:\Java\jdk1.8.0_121\jre\lib\ext\access-bridge-64.jar;F:\Java\jdk1.8.0_121\jre\lib\ext\cldrdata.jar;F:\Java\jdk1.8.0_121\jre\lib\ext\dnsns.jar;F:\Java\jdk1.8.0_121\jre\lib\ext\jaccess.jar;F:\Java\jdk1.8.0_121\jre\lib\ext\jfxrt.jar;F:\Java\jdk1.8.0_121\jre\lib\ext\localedata.jar;F:\Java\jdk1.8.0_121\jre\lib\ext\nashorn.jar;F:\Java\jdk1.8.0_121\jre\lib\ext\sunec.jar;F:\Java\jdk1.8.0_121\jre\lib\ext\sunjce_provider.jar;F:\Java\jdk1.8.0_121\jre\lib\ext\sunmscapi.jar;F:\Java\jdk1.8.0_121\jre\lib\ext\sunpkcs11.jar;F:\Java\jdk1.8.0_121\jre\lib\ext\zipfs.jar;F:\Java\jdk1.8.0_121\jre\lib\javaws.jar;F:\Java\jdk1.8.0_121\jre\lib\jce.jar;F:\Java\jdk1.8.0_121\jre\lib\jfr.jar;F:\Java\jdk1.8.0_121\jre\lib\jfxswt.jar;F:\Java\jdk1.8.0_121\jre\lib\jsse.jar;F:\Java\jdk1.8.0_121\jre\lib\management-agent.jar;F:\Java\jdk1.8.0_121\jre\lib\plugin.jar;F:\Java\jdk1.8.0_121\jre\lib\resources.jar;F:\Java\jdk1.8.0_121\jre\lib\rt.jar;G:\lianxi\springboot\juc\target\classes;F:\maven\repository\org\springframework\boot\spring-boot-starter\2.2.1.RELEASE\spring-boot-starter-2.2.1.RELEASE.jar;F:\maven\repository\org\springframework\boot\spring-boot\2.2.1.RELEASE\spring-boot-2.2.1.RELEASE.jar;F:\maven\repository\org\springframework\spring-context\5.2.1.RELEASE\spring-context-5.2.1.RELEASE.jar;F:\maven\repository\org\springframework\spring-aop\5.2.1.RELEASE\spring-aop-5.2.1.RELEASE.jar;F:\maven\repository\org\springframework\spring-beans\5.2.1.RELEASE\spring-beans-5.2.1.RELEASE.jar;F:\maven\repository\org\springframework\spring-expression\5.2.1.RELEASE\spring-expression-5.2.1.RELEASE.jar;F:\maven\repository\org\springframework\boot\spring-boot-autoconfigure\2.2.1.RELEASE\spring-boot-autoconfigure-2.2.1.RELEASE.jar;F:\maven\repository\org\springframework\boot\spring-boot-starter-logging\2.2.1.RELEASE\spring-boot-starter-logging-2.2.1.RELEASE.jar;F:\maven\repository\ch\qos\logback\logback-classic\1.2.3\logback-classic-1.2.3.jar;F:\maven\repository\ch\qos\logback\logback-core\1.2.3\logback-core-1.2.3.jar;F:\maven\repository\org\apache\logging\log4j\log4j-to-slf4j\2.12.1\log4j-to-slf4j-2.12.1.jar;F:\maven\repository\org\apache\logging\log4j\log4j-api\2.12.1\log4j-api-2.12.1.jar;F:\maven\repository\org\slf4j\jul-to-slf4j\1.7.29\jul-to-slf4j-1.7.29.jar;F:\maven\repository\jakarta\annotation\jakarta.annotation-api\1.3.5\jakarta.annotation-api-1.3.5.jar;F:\maven\repository\org\springframework\spring-core\5.2.1.RELEASE\spring-core-5.2.1.RELEASE.jar;F:\maven\repository\org\springframework\spring-jcl\5.2.1.RELEASE\spring-jcl-5.2.1.RELEASE.jar;F:\maven\repository\org\yaml\snakeyaml\1.25\snakeyaml-1.25.jar;F:\maven\repository\org\slf4j\slf4j-api\1.7.29\slf4j-api-1.7.29.jar com.example.juc.entity.Test
[null, null, 0312a4f3-6, 5eac6ecc-e, 73138495-9, 0ac213ad-0, e8be9fee-1, f402ebc8-c]
Exception in thread "2" Exception in thread "7" Exception in thread "6" Exception in thread "4" Exception in thread "1" Exception in thread "3" Exception in thread "16" Exception in thread "9" Exception in thread "23" Exception in thread "24" Exception in thread "27" Exception in thread "25" java.util.ConcurrentModificationException
	at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:901)
[null, null, 0312a4f3-6, 5eac6ecc-e, 73138495-9, 0ac213ad-0, e8be9fee-1, f402ebc8-c, b02c0889-c, 3d59d254-d, ec0aa6ec-5, 0755877d-6, 32da7f02-c, 76139987-a]
	at java.util.ArrayList$Itr.next(ArrayList.java:851)
	at java.util.AbstractCollection.toString(AbstractCollection.java:461)
	at java.lang.String.valueOf(String.java:2994)
[null, null, 0312a4f3-6, 5eac6ecc-e, 73138495-9, 0ac213ad-0, e8be9fee-1, f402ebc8-c, b02c0889-c, 3d59d254-d, ec0aa6ec-5, 0755877d-6, 32da7f02-c, 76139987-a, 4c8ff8a7-3]
	at java.io.PrintStream.println(PrintStream.java:821)
	at com.example.juc.entity.Test.lambda$main$0(Test.java:22)
	at java.lang.Thread.run(Thread.java:745)
[null, null, 0312a4f3-6, 5eac6ecc-e, 73138495-9, 0ac213ad-0, e8be9fee-1, f402ebc8-c, b02c0889-c, 3d59d254-d, ec0aa6ec-5, 0755877d-6, 32da7f02-c]
java.util.ConcurrentModificationException
	at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:901)
[null, null, 0312a4f3-6, 5eac6ecc-e, 73138495-9, 0ac213ad-0, e8be9fee-1, f402ebc8-c, b02c0889-c, 3d59d254-d, ec0aa6ec-5, 0755877d-6]
	at java.util.ArrayList$Itr.next(ArrayList.java:851)
	at java.util.AbstractCollection.toString(AbstractCollection.java:461)
[null, null, 0312a4f3-6, 5eac6ecc-e, 73138495-9, 0ac213ad-0, e8be9fee-1, f402ebc8-c, b02c0889-c, 3d59d254-d, ec0aa6ec-5, 0755877d-6, 32da7f02-c, 76139987-a, 4c8ff8a7-3, c971d789-4, 1a57b7df-3, 7cd1c317-1, ce25d0ba-c]
[null, null, 0312a4f3-6, 5eac6ecc-e, 73138495-9, 0ac213ad-0, e8be9fee-1, f402ebc8-c, b02c0889-c, 3d59d254-d, ec0aa6ec-5, 0755877d-6, 32da7f02-c, 76139987-a, 4c8ff8a7-3, c971d789-4, 1a57b7df-3, 7cd1c317-1, ce25d0ba-c, faf8f5a6-2]
[null, null, 0312a4f3-6, 5eac6ecc-e, 73138495-9, 0ac213ad-0, e8be9fee-1, f402ebc8-c, b02c0889-c, 3d59d254-d, ec0aa6ec-5, 0755877d-6, 32da7f02-c, 76139987-a, 4c8ff8a7-3, c971d789-4, 1a57b7df-3, 7cd1c317-1, ce25d0ba-c, faf8f5a6-2, 1a06c45f-5, 945fefd6-6]
[null, null, 0312a4f3-6, 5eac6ecc-e, 73138495-9, 0ac213ad-0, e8be9fee-1, f402ebc8-c, b02c0889-c, 3d59d254-d]
[null, null, 0312a4f3-6, 5eac6ecc-e, 73138495-9, 0ac213ad-0, e8be9fee-1, f402ebc8-c, b02c0889-c, 3d59d254-d, ec0aa6ec-5, 0755877d-6, 32da7f02-c, 76139987-a, 4c8ff8a7-3, c971d789-4, 1a57b7df-3, 7cd1c317-1, ce25d0ba-c, faf8f5a6-2, 1a06c45f-5, 945fefd6-6, 685ec419-5, f305b875-c, fc724a44-0, 50f2ea59-a, 38b82681-f, 9ae1ef9f-7]
[null, null, 0312a4f3-6, 5eac6ecc-e, 73138495-9, 0ac213ad-0, e8be9fee-1, f402ebc8-c, b02c0889-c, 3d59d254-d, ec0aa6ec-5, 0755877d-6, 32da7f02-c, 76139987-a, 4c8ff8a7-3, c971d789-4, 1a57b7df-3, 7cd1c317-1, ce25d0ba-c, faf8f5a6-2, 1a06c45f-5, 945fefd6-6, 685ec419-5, f305b875-c, fc724a44-0, 50f2ea59-a, 38b82681-f, 9ae1ef9f-7, 74661e01-4]
[null, null, 0312a4f3-6, 5eac6ecc-e, 73138495-9, 0ac213ad-0, e8be9fee-1, f402ebc8-c, b02c0889-c, 3d59d254-d, ec0aa6ec-5]
	at java.lang.String.valueOf(String.java:2994)
[null, null, 0312a4f3-6, 5eac6ecc-e, 73138495-9, 0ac213ad-0, e8be9fee-1, f402ebc8-c]
	at java.io.PrintStream.println(PrintStream.java:821)
	at com.example.juc.entity.Test.lambda$main$0(Test.java:22)
[null, null, 0312a4f3-6, 5eac6ecc-e, 73138495-9, 0ac213ad-0, e8be9fee-1, f402ebc8-c, b02c0889-c, 3d59d254-d, ec0aa6ec-5, 0755877d-6, 32da7f02-c, 76139987-a, 4c8ff8a7-3, c971d789-4, 1a57b7df-3, 7cd1c317-1, ce25d0ba-c, faf8f5a6-2, 1a06c45f-5, 945fefd6-6, 685ec419-5, f305b875-c, fc724a44-0, 50f2ea59-a, 38b82681-f, 9ae1ef9f-7, 74661e01-4, d01f6c9a-c]
	at java.lang.Thread.run(Thread.java:745)
java.util.ConcurrentModificationException
[null, null, 0312a4f3-6, 5eac6ecc-e, 73138495-9, 0ac213ad-0, e8be9fee-1, f402ebc8-c, b02c0889-c, 3d59d254-d, ec0aa6ec-5, 0755877d-6, 32da7f02-c, 76139987-a, 4c8ff8a7-3, c971d789-4, 1a57b7df-3, 7cd1c317-1, ce25d0ba-c, faf8f5a6-2, 1a06c45f-5, 945fefd6-6, 685ec419-5, f305b875-c, fc724a44-0]
	at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:901)
	at java.util.ArrayList$Itr.next(ArrayList.java:851)
[null, null, 0312a4f3-6, 5eac6ecc-e, 73138495-9, 0ac213ad-0, e8be9fee-1, f402ebc8-c, b02c0889-c, 3d59d254-d, ec0aa6ec-5, 0755877d-6, 32da7f02-c, 76139987-a, 4c8ff8a7-3, c971d789-4, 1a57b7df-3, 7cd1c317-1, ce25d0ba-c, faf8f5a6-2, 1a06c45f-5]
	at java.util.AbstractCollection.toString(AbstractCollection.java:461)
[null, null, 0312a4f3-6, 5eac6ecc-e, 73138495-9, 0ac213ad-0, e8be9fee-1, f402ebc8-c, b02c0889-c, 3d59d254-d, ec0aa6ec-5, 0755877d-6, 32da7f02-c, 76139987-a, 4c8ff8a7-3, c971d789-4, 1a57b7df-3, 7cd1c317-1]
	at java.lang.String.valueOf(String.java:2994)
[null, null, 0312a4f3-6, 5eac6ecc-e, 73138495-9, 0ac213ad-0, e8be9fee-1, f402ebc8-c, b02c0889-c, 3d59d254-d, ec0aa6ec-5, 0755877d-6, 32da7f02-c, 76139987-a, 4c8ff8a7-3, c971d789-4, 1a57b7df-3]
	at java.io.PrintStream.println(PrintStream.java:821)
	at com.example.juc.entity.Test.lambda$main$0(Test.java:22)
	at java.lang.Thread.run(Thread.java:745)
java.util.ConcurrentModificationException
	at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:901)
	at java.util.ArrayList$Itr.next(ArrayList.java:851)
	at java.util.AbstractCollection.toString(AbstractCollection.java:461)
	at java.lang.String.valueOf(String.java:2994)
	at java.io.PrintStream.println(PrintStream.java:821)
	at com.example.juc.entity.Test.lambda$main$0(Test.java:22)
	at java.lang.Thread.run(Thread.java:745)
java.util.ConcurrentModificationException
	at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:901)
	at java.util.ArrayList$Itr.next(ArrayList.java:851)
	at java.util.AbstractCollection.toString(AbstractCollection.java:461)
	at java.lang.String.valueOf(String.java:2994)
	at java.io.PrintStream.println(PrintStream.java:821)
	at com.example.juc.entity.Test.lambda$main$0(Test.java:22)
	at java.lang.Thread.run(Thread.java:745)
java.util.ConcurrentModificationException
	at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:901)
	at java.util.ArrayList$Itr.next(ArrayList.java:851)
	at java.util.AbstractCollection.toString(AbstractCollection.java:461)
	at java.lang.String.valueOf(String.java:2994)
	at java.io.PrintStream.println(PrintStream.java:821)
	at com.example.juc.entity.Test.lambda$main$0(Test.java:22)
	at java.lang.Thread.run(Thread.java:745)
java.util.ConcurrentModificationException
	at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:901)
	at java.util.ArrayList$Itr.next(ArrayList.java:851)
	at java.util.AbstractCollection.toString(AbstractCollection.java:461)
	at java.lang.String.valueOf(String.java:2994)
	at java.io.PrintStream.println(PrintStream.java:821)
	at com.example.juc.entity.Test.lambda$main$0(Test.java:22)
	at java.lang.Thread.run(Thread.java:745)
java.util.ConcurrentModificationException
	at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:901)
	at java.util.ArrayList$Itr.next(ArrayList.java:851)
	at java.util.AbstractCollection.toString(AbstractCollection.java:461)
	at java.lang.String.valueOf(String.java:2994)
	at java.io.PrintStream.println(PrintStream.java:821)
	at com.example.juc.entity.Test.lambda$main$0(Test.java:22)
	at java.lang.Thread.run(Thread.java:745)
java.util.ConcurrentModificationException
	at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:901)
	at java.util.ArrayList$Itr.next(ArrayList.java:851)
	at java.util.AbstractCollection.toString(AbstractCollection.java:461)
	at java.lang.String.valueOf(String.java:2994)
	at java.io.PrintStream.println(PrintStream.java:821)
	at com.example.juc.entity.Test.lambda$main$0(Test.java:22)
	at java.lang.Thread.run(Thread.java:745)
java.util.ConcurrentModificationException
	at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:901)
	at java.util.ArrayList$Itr.next(ArrayList.java:851)
	at java.util.AbstractCollection.toString(AbstractCollection.java:461)
	at java.lang.String.valueOf(String.java:2994)
	at java.io.PrintStream.println(PrintStream.java:821)
	at com.example.juc.entity.Test.lambda$main$0(Test.java:22)
	at java.lang.Thread.run(Thread.java:745)
java.util.ConcurrentModificationException
	at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:901)
	at java.util.ArrayList$Itr.next(ArrayList.java:851)
	at java.util.AbstractCollection.toString(AbstractCollection.java:461)
	at java.lang.String.valueOf(String.java:2994)
	at java.io.PrintStream.println(PrintStream.java:821)
	at com.example.juc.entity.Test.lambda$main$0(Test.java:22)
	at java.lang.Thread.run(Thread.java:745)
java.util.ConcurrentModificationException
	at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:901)
	at java.util.ArrayList$Itr.next(ArrayList.java:851)
	at java.util.AbstractCollection.toString(AbstractCollection.java:461)
	at java.lang.String.valueOf(String.java:2994)
	at java.io.PrintStream.println(PrintStream.java:821)
	at com.example.juc.entity.Test.lambda$main$0(Test.java:22)
	at java.lang.Thread.run(Thread.java:745)

Process finished with exit code 0

错误代码

public class Test {

    public static void main(String[] args) {
        List<String> list = new ArrayList<>();
        for (int i = 1; i <= 30; i++) {
            new Thread(() -> {
                list.add(UUID.randomUUID().toString().substring(0, 10));
                System.out.println(list);
            }, String.valueOf(i)).start();
        }
    }
}

解决方案1

public class Test {

    public static void main(String[] args) {
        List<String> list = new Vector<>();
        for (int i = 1; i <= 30; i++) {
            new Thread(() -> {
                list.add(UUID.randomUUID().toString().substring(0, 10));
                System.out.println(list);
            }, String.valueOf(i)).start();
        }
    }
}

打印结果:
在这里插入图片描述

解决方案2:

public class Test {

    public static void main(String[] args) {
        List<String> list = Collections.synchronizedList(new ArrayList<>());
        for (int i = 1; i <= 30; i++) {
            new Thread(() -> {
                list.add(UUID.randomUUID().toString().substring(0, 10));
                System.out.println(list);
            }, String.valueOf(i)).start();
        }
    }
}

打印结果:
在这里插入图片描述
解决方案3:

package com.example.juc.entity;

import java.util.*;
import java.util.concurrent.CopyOnWriteArrayList;


/**
 * 1.故障现象: java.util.ConcurrentModificationException
 * 2.导致原因:
 * 3.解决办法:
 * 3.1.new Vector<>();
 * 3.2.Collections.synchronizedList(new ArrayList<>());
 * 3.3.new CopyOnWriteArrayList();
 */
public class Test {

    public static void main(String[] args) {
        List<String> list = new CopyOnWriteArrayList();
        for (int i = 1; i <= 30; i++) {
            new Thread(() -> {
                list.add(UUID.randomUUID().toString().substring(0, 10));
                System.out.println(list);
            }, String.valueOf(i)).start();
        }
    }
}

打印结果:
在这里插入图片描述