小编Des*_*tes的帖子

如何在Java中找到两个长值的模数(%)？我的代码说'整数太大'后跟我想要修改的数字.我尝试将它投入很长时间但它没有用.我是否必须将其转换为BigInteger并使用余数方法？谢谢.

我需要找到非常大的乘法(每个约300位)的位数.我想知道是否有一个技巧来预测产品没有实际执行计算的位数.

我正在使用 Jackson 反序列化服务器返回的 XML 文件。我收到 UnrecognizedPropertyException 错误消息“无法识别的字段”“”。

有问题的 XML：

<Identifiers>
    <Identifier type="Organisational Study">Q2736g</Identifier>
    <Identifier type="NCT">NCT00109200</Identifier>
</Identifiers>

堆栈跟踪：

com.fasterxml.jackson.databind.exc.UnrecognizedPropertyException: Unrecognized field "" (class sloan.scraper.Trial$Identifier), not marked as ignorable (3 known properties: , "data2", "type", "data"])
 at [Source: java.io.StringReader@28c2f254; line: 1, column: 547] (through reference chain: sloan.mit.cortellisScraper.Trial["Identifiers"]->sloan.mit.cortellisScraper.Identifier[""])
    at com.fasterxml.jackson.databind.exc.UnrecognizedPropertyException.from(UnrecognizedPropertyException.java:79)
    at com.fasterxml.jackson.databind.DeserializationContext.reportUnknownProperty(DeserializationContext.java:579)
    at com.fasterxml.jackson.databind.deser.std.StdDeserializer.handleUnknownProperty(StdDeserializer.java:672)
    at com.fasterxml.jackson.databind.deser.BeanDeserializerBase.handleUnknownProperty(BeanDeserializerBase.java:906)
    at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:328)
    at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:121)
    at com.fasterxml.jackson.databind.deser.std.ObjectArrayDeserializer.deserialize(ObjectArrayDeserializer.java:147)
    at com.fasterxml.jackson.databind.deser.std.ObjectArrayDeserializer.deserialize(ObjectArrayDeserializer.java:18)
    at com.fasterxml.jackson.databind.deser.SettableBeanProperty.deserialize(SettableBeanProperty.java:375)
    at com.fasterxml.jackson.databind.deser.impl.FieldProperty.deserializeAndSet(FieldProperty.java:107)
    at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:308)
    at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:121)
    at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:2796)
    at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:1942)
    at sloan.mit.cortellisScraper.Main.fetchJson(Main.java:173)
    at sloan.mit.cortellisScraper.Main.main(Main.java:64)

如何使用 Jackson 来拯救未识别的字段？

在下面的代码中,我试图检查int(转换为String)是否包含重复的数字.

public static boolean hasDupes(int n)
  {
    String number = new String();
    number = Integer.toString(n);
    int digit = 0;
    System.out.println(num.indexOf(digit));
    System.out.println(num.lastIndexOf(digit));
    while(digit < 10)
    {
      if(number.indexOf(digit) != number.lastIndexOf(digit))
      {
        return true; 
      }
      digit++;
    }
    //System.out.println(n);
    return false;
  }

我加入了这些System.out.println行,因为我不确定为什么我的方法不起作用.它们总是打印出'-1'.我不明白索引如何-1,以及为什么它不起作用.