本文整理了Java中net.sf.saxon.om.Item.head()方法的一些代码示例，展示了Item.head()的具体用法。这些代码示例主要来源于Github/Stackoverflow/Maven等平台，是从一些精选项目中提取出来的代码，具有较强的参考意义，能在一定程度帮忙到你。Item.head()方法的具体详情如下：
包路径：net.sf.saxon.om.Item
类名称：Item
方法名：head

Item.head介绍

[英]Get the first item in the sequence. Differs from the superclass Sequence in that * no exception is thrown.
[中]获取序列中的第一项。与超类序列的不同之处在于*不会引发异常。

代码示例

代码示例来源：origin: org.apache.servicemix.bundles/org.apache.servicemix.bundles.saxon

/**
 * Get the n'th item in the value, counting from 0
 *
 * @param n the index of the required item, with 0 representing the first item in the sequence
 * @return the n'th item if it exists, or null otherwise
 */
default T itemAt(int n) {
  return n == 0 ? head() : null;
}

代码示例来源：origin: net.sf.saxon/Saxon-HE

/**
 * Get the n'th item in the value, counting from 0
 *
 * @param n the index of the required item, with 0 representing the first item in the sequence
 * @return the n'th item if it exists, or null otherwise
 */
default T itemAt(int n) {
  return n == 0 ? head() : null;
}

代码示例来源：origin: org.daisy.libs/com.xmlcalabash

@Override
public Item getItem(XPathContext context) throws XPathException {
  return doc.getUnderlyingValue().head();
}

代码示例来源：origin: org.apache.servicemix.bundles/org.apache.servicemix.bundles.saxon

/**
 * Get an iterator over all the items in the sequence
 *
 * @return an iterator over all the items
 */
default UnfailingIterator<T> iterate() {
  return SingletonIterator.makeIterator(head());
}

代码示例来源：origin: net.sf.saxon/Saxon-HE

/**
 * Get an iterator over all the items in the sequence
 *
 * @return an iterator over all the items
 */
default UnfailingIterator<T> iterate() {
  return SingletonIterator.makeIterator(head());
}

代码示例来源：origin: net.sf.saxon/Saxon-HE

/**
 * Get the contents of this value in the form of a Java {@link java.util.Iterator},
 * so that the sequence value can be used in a for-each expression
 *
 * @return an Iterator delivering a sequence of items containing this single item only
 */
default Iterator<T> iterator() {
  return new MonoIterator<>(head());
}

代码示例来源：origin: com.xmlcalabash/xmlcalabash

@Override
public Item getItem(XPathContext context) throws XPathException {
  return doc.getUnderlyingValue().head();
}

代码示例来源：origin: org.apache.servicemix.bundles/org.apache.servicemix.bundles.saxon

/**
 * Get the contents of this value in the form of a Java {@link java.util.Iterator},
 * so that the sequence value can be used in a for-each expression
 *
 * @return an Iterator delivering a sequence of items containing this single item only
 */
default Iterator<T> iterator() {
  return new MonoIterator<>(head());
}

代码示例来源：origin: net.sf.saxon/Saxon-HE

/**
 * Set the context item for evaluating the XPath expression.
 * This may be either a node or an atomic value. Most commonly it will be a document node,
 * which might be constructed using the {@link DocumentBuilder#build} method.
 *
 * @param item The context item for evaluating the expression. Must not be null.
 * @throws SaxonApiException if an error occurs, for example because the type
 *                           of item supplied does not match the required item type
 */
public void setContextItem(XdmItem item) throws SaxonApiException {
  if (item == null) {
    throw new NullPointerException("contextItem");
  }
  if (!exp.getInternalExpression().getPackageData().isSchemaAware()) {
    Item it = item.getUnderlyingValue().head();
    if (it instanceof NodeInfo && ((NodeInfo) it).getTreeInfo().isTyped()) {
      throw new SaxonApiException(
        "The supplied node has been schema-validated, but the XPath expression was compiled without schema-awareness");
    }
  }
  try {
    dynamicContext.setContextItem(item.getUnderlyingValue());
  } catch (XPathException e) {
    throw new SaxonApiException(e);
  }
}

代码示例来源：origin: net.sf.saxon/Saxon-HE

Set<MutableNodeInfo> affectedDocuments =
    exp.getUnderlyingCompiledQuery().runUpdate(evaluator.getUnderlyingQueryContext());
Item initial = evaluator.getContextItem().getUnderlyingValue().head();

代码示例来源：origin: org.apache.servicemix.bundles/org.apache.servicemix.bundles.saxon

/**
 * Set the context item for evaluating the XPath expression.
 * This may be either a node or an atomic value. Most commonly it will be a document node,
 * which might be constructed using the {@link DocumentBuilder#build} method.
 *
 * @param item The context item for evaluating the expression. Must not be null.
 * @throws SaxonApiException if an error occurs, for example because the type
 *                           of item supplied does not match the required item type
 */
public void setContextItem(XdmItem item) throws SaxonApiException {
  if (item == null) {
    throw new NullPointerException("contextItem");
  }
  if (!exp.getInternalExpression().getPackageData().isSchemaAware()) {
    Item it = item.getUnderlyingValue().head();
    if (it instanceof NodeInfo && ((NodeInfo) it).getTreeInfo().isTyped()) {
      throw new SaxonApiException(
        "The supplied node has been schema-validated, but the XPath expression was compiled without schema-awareness");
    }
  }
  try {
    dynamicContext.setContextItem(item.getUnderlyingValue());
  } catch (XPathException e) {
    throw new SaxonApiException(e);
  }
}

代码示例来源：origin: org.apache.servicemix.bundles/org.apache.servicemix.bundles.saxon

Set<MutableNodeInfo> affectedDocuments =
    exp.getUnderlyingCompiledQuery().runUpdate(evaluator.getUnderlyingQueryContext());
Item initial = evaluator.getContextItem().getUnderlyingValue().head();