How to use

lookupNamespacePrefix

method

in

com.android.utils.XmlUtils

private static String getAndroidPrefix(@NonNull Element xml) {
  String toolsPrefix = XmlUtils.lookupNamespacePrefix(
      xml, SdkConstants.ANDROID_URI, SdkConstants.ANDROID_NS_NAME, false);
  if (!toolsPrefix.equals(SdkConstants.ANDROID_NS_NAME) && xml.getOwnerDocument()
      .getDocumentElement().getAttribute("xmlns:" + toolsPrefix) == null) {
    // this is weird, the document is using "android" prefix but it's not bound
    // to our namespace. Add the proper xmlns declaration.
    xml.setAttribute("xmlns:" + toolsPrefix, SdkConstants.ANDROID_URI);
  }
  return toolsPrefix;
}

public OrphanXmlElement(@NonNull Element xml) {
  mXml = Preconditions.checkNotNull(xml);
  NodeTypes nodeType;
  String elementName = mXml.getNodeName();
  // this is bit more complicated than it should be. Look first if there is a namespace
  // prefix in the name, most elements don't. If they do, however, strip it off if it is the
  // android prefix, but if it's custom namespace prefix, classify the node as CUSTOM.
  int indexOfColon = elementName.indexOf(':');
  if (indexOfColon != -1) {
    String androidPrefix = XmlUtils.lookupNamespacePrefix(xml, SdkConstants.ANDROID_URI);
    if (androidPrefix.equals(elementName.substring(0, indexOfColon))) {
      nodeType = NodeTypes.fromXmlSimpleName(elementName.substring(indexOfColon + 1));
    } else {
      nodeType = NodeTypes.CUSTOM;
    }
  } else {
    nodeType = NodeTypes.fromXmlSimpleName(elementName);
  }
  mType = nodeType;
}

  /**
   * Removes the android namespace from an element recursively.
   *
   * @param element the element
   */
  private void clearNodeNamespaces(Element element) {
    String androidPrefix = XmlUtils.lookupNamespacePrefix(element, SdkConstants.ANDROID_URI);

    String name = element.getNodeName();
    int colonIdx = name.indexOf(':');
    if (colonIdx != -1) {
      String prefix = name.substring(0, colonIdx);
      if (prefix.equals(androidPrefix)) {
        String newName = name.substring(colonIdx + 1);
        getXml().renameNode(element, null, newName);
      }
    }

    NodeList childrenNodeList = element.getChildNodes();
    for (int i = 0; i < childrenNodeList.getLength(); i++) {
      Node n = childrenNodeList.item(i);
      if (n instanceof Element) {
        clearNodeNamespaces((Element) n);
      }
    }
  }
}

/**
 * Returns the namespace prefix matching the requested namespace URI.
 * If no such declaration is found, returns the default "android" prefix for
 * the Android URI, and "app" for other URI's. By default the app namespace
 * will be created. If this is not desirable, call
 * {@link #lookupNamespacePrefix(Node, String, boolean)} instead.
 *
 * @param node The current node. Must not be null.
 * @param nsUri The namespace URI of which the prefix is to be found,
 *              e.g. {@link SdkConstants#ANDROID_URI}
 * @return The first prefix declared or the default "android" prefix
 *              (or "app" for non-Android URIs)
 */
@NonNull
public static String lookupNamespacePrefix(@NonNull Node node, @NonNull String nsUri) {
  String defaultPrefix = ANDROID_URI.equals(nsUri) ? ANDROID_NS_NAME : APP_PREFIX;
  return lookupNamespacePrefix(node, nsUri, defaultPrefix, true /*create*/);
}

/**
 * Returns the namespace prefix matching the requested namespace URI. If no
 * such declaration is found, returns the default "android" prefix for the
 * Android URI, and "app" for other URI's.
 *
 * @param node The current node. Must not be null.
 * @param nsUri The namespace URI of which the prefix is to be found, e.g.
 *            {@link SdkConstants#ANDROID_URI}
 * @param create whether the namespace declaration should be created, if
 *            necessary
 * @return The first prefix declared or the default "android" prefix (or
 *         "app" for non-Android URIs)
 */
@NonNull
public static String lookupNamespacePrefix(@NonNull Node node, @NonNull String nsUri,
    boolean create) {
  String defaultPrefix = ANDROID_URI.equals(nsUri) ? ANDROID_NS_NAME : APP_PREFIX;
  return lookupNamespacePrefix(node, nsUri, defaultPrefix, create);
}

if (attributeName.indexOf(XmlUtils.NS_SEPARATOR) == -1) {
  String toolsPrefix = XmlUtils
      .lookupNamespacePrefix(getXml(), SdkConstants.TOOLS_URI,
          SdkConstants.ANDROID_NS_NAME, false);