ConcurrentModificationException (Java 2 Platform SE 5.0)

Sat Oct 11 17:16:48 CST 2008发表于Delicious/searchfull

java.util.ConcurrentModificationException异常

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Java ConcurrentModificationException

I was troubleshooting a multi-threaded application for a occasional exception. Run the following code public static void main(String[] args){ Map context = new HashMap (1); context.put(“key_1″, “value_1″); context.put(“key_2″, “value_2″); for (String key: context.keySet()){ System.out.println(context.get(key)); context.remove(key); } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace;

Holliday Java Quiz: ConcurrentModificationException

Weiqi Gao's Observations (29 reads)

Tomorrow is Thanksgiving in the US. And here is a little Java quiz that you may want to ponder on while the turkey is in the oven. (BTW, I just recently realized I've been pronouncing the word 'oven' wrong all these years. Apparently it's not [oh-vn], but [uh-vn].)

Q: For the following Foo.java, is it ever possible for line 21 to throw a java.util.ConcurrentModificationException?

    1    import java.util.ArrayList; 
    2    import java.util.List; 
    3     
    4    public class Foo { 
    5      private final List<Bar> bars = new ArrayList<Bar>(); 
    6     
    7      public void add(Bar bar) { 
    8        synchronized(bars) { 
    9          bars.add(bar); 
    10       } 
    11     } 
    12    
    13     public void remove(Bar bar) { 
    14       synchronized(bars) { 
    15         bars.remove(bar); 
    16       } 
    17     } 
    18    
    19     public void close() { 
    20       synchronized(bars) { 
    21         for (Bar bar: bars) { 
    22           bar.close(); 
    23         } 
    24         bars.clear(); 
    25       } 
    26     } 
    27   }

Have a happy Thanksgiving.

Holiday Java Quiz: ConcurrentModificationException

Holliday Java Quiz: ConcurrentModificationException

Q: For the following Foo.java, is it ever possible for line 21 to throw a java.util.ConcurrentModificationException?

    1    import java.util.ArrayList; 
    2    import java.util.List; 
    3     
    4    public class Foo { 
    5      private final List<Bar> bars = new ArrayList<Bar>(); 
    6     
    7      public void add(Bar bar) { 
    8        synchronized(bars) { 
    9          bars.add(bar); 
    10       } 
    11     } 
    12    
    13     public void remove(Bar bar) { 
    14       synchronized(bars) { 
    15         bars.remove(bar); 
    16       } 
    17     } 
    18    
    19     public void close() { 
    20       synchronized(bars) { 
    21         for (Bar bar: bars) { 
    22           bar.close(); 
    23         } 
    24         bars.clear(); 
    25       } 
    26     } 
    27   }

Have a happy Thanksgiving.

Java Platform

The Java platform consists of: 1. the Java application programming interfaces (APIs) and 2. the Java Virtual Machine (JVM). A Java program which is written in Java language just can be run in computer which has installed the Java Platform. Java Language defines the syntax and semantics of the Java programming language. It defines basic vocabulary such as primitive types, if/else blocks, the syntax of class declaration, exception syntax, variable scoping rules, and everything else necessa