如何使用xml解析器解决java.lang.string无法转换为java.lang.integer android
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时间：2020-08-11 18:24:27 来源:igfitidea点击:
how to resolve java.lang.string cannot be cast to java.lang.integer android with xml parser
提问by developer
I am trying to parse XML and display it into list view, but after running the app nothing happens -- the list is displayed but not with the XML data . I don't know if I am missing something.
我正在尝试解析 XML 并将其显示到列表视图中，但是在运行应用程序后什么也没有发生 - 列表显示但不包含 XML 数据。我不知道我是否遗漏了什么。
MainActivity class
主活动类
public class MainActivity extends ListActivity {
// All static variables
static final String URL = "http://api.androidhive.info/pizza/?format=xml";
// XML node keys
static final String KEY_ITEM = "item"; // parent node
static final String KEY_ID = "id";
static final String KEY_NAME = "name";
static final String KEY_COST = "cost";
static final String KEY_DESC = "description";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (android.os.Build.VERSION.SDK_INT > 9) {
StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);
}
ListView myList=(ListView)findViewById(android.R.id.list);
ArrayList<HashMap<String, String>> menuItems = new ArrayList<HashMap<String, String>>();
XMLParser parser = new XMLParser();
String xml = null; // getting XML
try {
xml = parser.getXmlFormUrl(URL);
} catch (IOException e) {
e.printStackTrace();
}
Document doc = parser.getDomElement(xml); // getting DOM element
NodeList nl = doc.getElementsByTagName(KEY_ITEM);
// looping through all item nodes <item>
for (int i = 0; i < nl.getLength(); i++) {
// creating new HashMap
HashMap<String, String> map = new HashMap<String, String>();
Element e = (Element) nl.item(i);
// adding each child node to HashMap key => value
map.put(KEY_ID, parser.getValue(e, KEY_ID));
map.put(KEY_NAME, parser.getValue(e, KEY_NAME));
map.put(KEY_COST, "Rs." + parser.getValue(e, KEY_COST));
map.put(KEY_DESC, parser.getValue(e, KEY_DESC));
// adding HashList to ArrayList
menuItems.add(map);
}
// Adding menuItems to ListView
ListAdapter adapter = new SimpleAdapter(this, menuItems,
R.layout.activity_main,
new String[] { KEY_NAME, KEY_DESC, KEY_COST }, new int[] {
R.id.name, R.id.desciption, R.id.cost });
setListAdapter(adapter);
// selecting single ListView item
}
}
}
XmlParser class
XmlParser 类
public class XMLParser {
String result;
public String getXmlFormUrl(String link) throws IOException{
URL url=new URL(link.toString());
HttpURLConnection UrlConnection= (HttpURLConnection) url.openConnection();
int status=UrlConnection.getResponseCode();
if(status==200){
InputStream inputStream=UrlConnection.getInputStream();
BufferedReader bufferedReader=new BufferedReader(new InputStreamReader(inputStream,"UTF8"));
StringBuilder stringBuilder= new StringBuilder();
String line;
while ((line=bufferedReader.readLine())!=null){
stringBuilder.append((line+"\n"));
}
result=stringBuilder.toString();
inputStream.close();
}
return result;
}
public Document getDomElement(String xml){
Document doc = null;
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
try {
DocumentBuilder db = dbf.newDocumentBuilder();
InputSource is = new InputSource();
is.setCharacterStream(new StringReader(xml));
doc = db.parse(is);
} catch (ParserConfigurationException e) {
Log.e("Error: ", e.getMessage());
return null;
} catch (SAXException e) {
Log.e("Error: ", e.getMessage());
return null;
} catch (IOException e) {
Log.e("Error: ", e.getMessage());
return null;
}
// return DOM
return doc;
}
public String getValue(Element item, String str) {
NodeList n = item.getElementsByTagName(str);
return this.getElementValue(n.item(0));
}
public final String getElementValue( Node elem ) {
Node child;
if( elem != null){
if (elem.hasChildNodes()){
for( child = elem.getFirstChild(); child != null; child = child.getNextSibling() ){
if( child.getNodeType() == Node.TEXT_NODE ){
return child.getNodeValue();
}
}
}
}
return "";
}
}
}
ActivityMain.xml
ActivityMain.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="android.prgguru.com.xmlparsingg.MainActivity">
<ListView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@android:id/list"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginTop="73dp" />
</RelativeLayout>logcat
日志猫
2/? E/ActivityThread: Service com.google.android.gms.car.CarService has leaked ServiceConnection com.google.android.gms.car.hr@3bb3cd94 that was originally bound here
android.app.ServiceConnectionLeaked: Service com.google.android.gms.car.CarService has leaked ServiceConnection com.google.android.gms.car.hr@3bb3cd94 that was originally bound here
at android.app.LoadedApk$ServiceDispatcher.<init>(LoadedApk.java:1083)
at android.app.LoadedApk.getServiceDispatcher(LoadedApk.java:977)
at android.app.ContextImpl.bindServiceCommon(ContextImpl.java:1779)
at android.app.ContextImpl.bindService(ContextImpl.java:1762)
at android.content.ContextWrapper.bindService(ContextWrapper.java:539)
at android.content.ContextWrapper.bindService(ContextWrapper.java:539)
at android.content.ContextWrapper.bindService(ContextWrapper.java:539)
at com.google.android.gms.common.stats.g.a(:com.google.android.gms:128)
at com.google.android.gms.common.stats.g.a(:com.google.android.gms:145)
at com.google.android.gms.car.hc.<init>(:com.google.android.gms:319)
at com.google.android.gms.car.CarChimeraService.onCreate(:com.google.android.gms:74)
at com.google.android.chimera.container.ServiceProxy.setImpl(:com.google.android.gms:119)
at com.google.android.chimera.container.ServiceProxy.onCreate(:com.google.android.gms:109)
at android.app.ActivityThread.handleCreateService(ActivityThread.java:2825)
at android.app.ActivityThread.access00(ActivityThread.java:156)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1434)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:211)
at android.app.ActivityThread.main(ActivityThread.java:5373)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1020)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:815)采纳答案by Vikrant Kashyap
You cannot directly change or reference your Stringobject to Integertype because there is no parent-childrelationship between these two classes.
您不能直接更改或引用String要Integer键入的对象，因为parent-child这两个类之间没有关系。
If you try to casta Stringto a Integerin such a way, it will raise a ClassCastException.
如果你以这种方式尝试castaString到 a Integer，它会引发 a ClassCastException。
String someValue = "123";
Integer intValue = (Integer) someValue; // ClassCastException Raise.
So if you want to change or reference a StringVariable to Integer, you must use parsing techniques.
因此，如果要将String变量更改或引用到Integer，则必须使用解析技术。
int intValue = Integer.parseInt(someValue); //this code will work for this.
回答by marti201
If you have a String and you are sure that the only thing in it is a whole number without spaces, you can use Integer.parseInt(String)to convert it to an integer. This method will throw an exception if the string isn't just the number.
如果您有一个 String 并且您确定其中唯一的内容是一个没有空格Integer.parseInt(String)的整数，则可以使用将其转换为整数。如果字符串不仅仅是数字，则此方法将引发异常。
