java - 将 XML 文件导入 Java 处理时出现 NullPointerException

Question

我正在尝试从 XML 文件获取数据并在处理中使用该数据。当我这样做时，我得到了 NPE，但我不太明白我错在哪里。 XML 有多个层，我必须从这个“子项”获取数据:

http://i62.tinypic.com/2mb90g.png

我的代码如下所示:

XML xml;

void setup(){

xml = loadXML("parker.xml");

XML[] children = xml.getChildren("kml");

XML[] Folder=children[0].getChildren("Folder");

XML[] Placemark=Folder[1].getChildren("Placemark");

XML[] Polygon=Placemark[2].getChildren("Polygon");

XML[] outerBoundaryIs=Polygon[3].getChildren("outerBoundaryIs");

XML[] LinearRing=outerBoundaryIs[4].getChildren("LinearRing");

  for (int i = 0; i < LinearRing.length; i++) {
    float coordinates = children[i].getFloat("coordinates");
    println(coordinates);

  }
}

最好的克里斯

堆栈跟踪:

[Fatal Error] :1:1: Content is not allowed in prolog. org.xml.sax.SAXParseException; lineNumber: 1; columnNumber: 1; Content is not allowed in prolog. at com.sun.org.apache.xerces.internal.parsers.DOMParser.parse(DOMParser.java:257) at com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl.parse(DocumentBuilderImpl.java:347) at processing.data.XML.(XML.java:187) at processing.core.PApplet.loadXML(PApplet.java:6310) at processing.core.PApplet.loadXML(PApplet.java:6300) at XMLtryout.setup(XMLtryout.java:21) at processing.core.PApplet.handleDraw(PApplet.java:2359) at processing.core.PGraphicsJava2D.requestDraw(PGraphicsJava2D.java:240) at processing.core.PApplet.run(PApplet.java:2254) at java.lang.Thread.run(Thread.java:744)

XML 文件:

https://www.dropbox.com/s/xn3thjskhlf2wai/parker.xml

Answer 1

此错误可能是由于您的 xml 文件顶部缺少此内容而引起的

<?xml version="1.0" encoding="utf-8"?>

或者文件开头有一些不可打印的垃圾。