Skip the wrong csv line

Question

I am trying to read csv and add fields to the data structure. But one of the lines is not formed properly, and I know that. I just want to skip a line and move on to another. But, although I caught the exception, it still breaks the loop. Any idea what I'm missing here?

My csv:

"id","name","email"
121212,"Steve","[e-mail]"
121212,"Steve","[e-mail]",,
121212,"Steve","[e-mail]"

My code is:

import com.fasterxml.jackson.databind.MappingIterator;
import com.fasterxml.jackson.dataformat.csv.CsvMapper;
import com.fasterxml.jackson.dataformat.csv.CsvSchema;

public static void main(String[] args) throws Exception{
    Path path = Paths.get("list2.csv");
    CsvMapper mapper = new CsvMapper();
    CsvSchema schema = CsvSchema.emptySchema().withHeader();
    MappingIterator<Object> it = mapper.reader(Object.class)
            .with(schema)
            .readValues(path.toFile());

    try{
        while(it.hasNext()){
            Object row;
            try{
                row = it.nextValue();
            } catch (IOException e){
                e.printStackTrace();
                continue;
            }
        }
    } catch (ArrayIndexOutOfBoundsException e){
        e.printStackTrace();
    }

}

An exception:

com.fasterxml.jackson.core.JsonParseException: Too many entries: expected at most 3 (value #3 (0 chars) "")
 at [Source: java.io.InputStreamReader@12b3519c; line: 3, column: 38]
    at com.fasterxml.jackson.core.JsonParser._constructError(JsonParser.java:1486)
    at com.fasterxml.jackson.core.base.ParserMinimalBase._reportError(ParserMinimalBase.java:518)
    at com.fasterxml.jackson.dataformat.csv.CsvParser._handleNextEntryExpectEOL(CsvParser.java:601)
    at com.fasterxml.jackson.dataformat.csv.CsvParser._handleNextEntry(CsvParser.java:587)
    at com.fasterxml.jackson.dataformat.csv.CsvParser.nextToken(CsvParser.java:474)
    at com.fasterxml.jackson.databind.deser.std.UntypedObjectDeserializer$Vanilla.mapObject(UntypedObjectDeserializer.java:592)
    at com.fasterxml.jackson.databind.deser.std.UntypedObjectDeserializer$Vanilla.deserialize(UntypedObjectDeserializer.java:440)
    at com.fasterxml.jackson.databind.MappingIterator.nextValue(MappingIterator.java:188)
    at CSVTest.main(CSVTest.java:24)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:140)
java.lang.ArrayIndexOutOfBoundsException: 3
    at com.fasterxml.jackson.dataformat.csv.CsvSchema.column(CsvSchema.java:941)
    at com.fasterxml.jackson.dataformat.csv.CsvParser._handleNamedValue(CsvParser.java:614)
    at com.fasterxml.jackson.dataformat.csv.CsvParser.nextToken(CsvParser.java:476)
    at com.fasterxml.jackson.databind.MappingIterator.hasNextValue(MappingIterator.java:158)
    at CSVTest.main(CSVTest.java:21)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:140)

Answer 1

With processing, Jackson 2.6 has readValues()been improved to try to repair processing errors, so in many cases you can just try again to read the following valid lines. Therefore, do not forget to use at least the version 2.6.2.

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Answer 2

com.fasterxml.jackson.core.JsonParseException IOException, try-catch. , , , hasNext(). : , , .

Answer 3

CSV , .

univocity-parsers .

:

BeanListProcessor<TestBean> rowProcessor = new BeanListProcessor<TestBean>(TestBean.class);

CsvParserSettings parserSettings = new CsvParserSettings();
parserSettings.setRowProcessor(rowProcessor);
parserSettings.setHeaderExtractionEnabled(true);

CsvParser parser = new CsvParser(parserSettings);
parser.parse(new FileReader(Paths.get("list2.csv").toFile());

// The BeanListProcessor provides a list of objects extracted from the input.
List<TestBean> beans = rowProcessor.getBeans();

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Answer 4

, , :

• ArrayIndexOutOfBoundsException - , ( "cause" ), , .
• () IOException, , , it.hasNext(), , .

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---

---

:

24 CSVTest.java .nextValue(). JsonParseException. IOException, catch , . .

com.fasterxml.jackson.core.JsonParseException: Too many entries: expected at most 3 (value #3 (0 chars) "")
 at [Source: java.io.InputStreamReader@12b3519c; line: 3, column: 38]
   at com.fasterxml.jackson.core.JsonParser._constructError(JsonParser.java:1486)
   at com.fasterxml.jackson.core.base.ParserMinimalBase._reportError(ParserMinimalBase.java:518)
   at com.fasterxml.jackson.dataformat.csv.CsvParser._handleNextEntryExpectEOL(CsvParser.java:601)
   at com.fasterxml.jackson.dataformat.csv.CsvParser._handleNextEntry(CsvParser.java:587)
   at com.fasterxml.jackson.dataformat.csv.CsvParser.nextToken(CsvParser.java:474)
   at com.fasterxml.jackson.databind.deser.std.UntypedObjectDeserializer$Vanilla.mapObject(UntypedObjectDeserializer.java:592)
   at com.fasterxml.jackson.databind.deser.std.UntypedObjectDeserializer$Vanilla.deserialize(UntypedObjectDeserializer.java:440)
   at com.fasterxml.jackson.databind.MappingIterator.nextValue(MappingIterator.java:188)
   at CSVTest.main(CSVTest.java:24)

21 CSVTest.java .hasNextValue(). ArrayIndexOutOfBoundsException. , . catch , , , .

java.lang.ArrayIndexOutOfBoundsException: 3
    at com.fasterxml.jackson.dataformat.csv.CsvSchema.column(CsvSchema.java:941)
    at com.fasterxml.jackson.dataformat.csv.CsvParser._handleNamedValue(CsvParser.java:614)
    at com.fasterxml.jackson.dataformat.csv.CsvParser.nextToken(CsvParser.java:476)
    at com.fasterxml.jackson.databind.MappingIterator.hasNextValue(MappingIterator.java:158)
    at CSVTest.main(CSVTest.java:21)

, try-catch . , :

while (true)
    {
    try
        {
        if (!it.hasNextValue())
            { break; }
        }
    catch (final ArrayIndexOutOfBoundsException err)
        {
        err.printStackTrace();
        continue;
        }

    Object row;
    try
        { row = it.nextValue(); }
    catch (final IOException err)
        {
        err.printStackTrace();
        continue;
        }
    }

However , this code is an infinite loop. When an hasNextValue()ArrayIndexOutOfBoundsException throws an exception, the state has not changed, the loop will never end. I show this to show the principle of moving the catch block inside the loop, and not as a workable resolution.

You added a comment to the question regarding the discussion of error handling in jackson-dataformat-csv. It looks like you are faced with a restriction (or error) in the library when it comes to skipping the wrong lines.