android解析xml NullPointerException

你好，我的应用程序有问题，当我运行它时，它停止了。这让我明白：

    09-19 11:15:42.941: W/dalvikvm(6202): threadid=1: thread exiting with uncaught exception (group=0x40a71930)
09-19 11:15:43.083: E/AndroidRuntime(6202): FATAL EXCEPTION: main
09-19 11:15:43.083: E/AndroidRuntime(6202): java.lang.RuntimeException: Unable to start activity ComponentInfo{cz.bakalari.bakalari/cz.bakalari.bakalari.ParseActivity}: java.lang.NullPointerException
09-19 11:15:43.083: E/AndroidRuntime(6202):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
09-19 11:15:43.083: E/AndroidRuntime(6202):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
09-19 11:15:43.083: E/AndroidRuntime(6202):     at android.app.ActivityThread.access$600(ActivityThread.java:141)
09-19 11:15:43.083: E/AndroidRuntime(6202):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
09-19 11:15:43.083: E/AndroidRuntime(6202):     at android.os.Handler.dispatchMessage(Handler.java:99)
09-19 11:15:43.083: E/AndroidRuntime(6202):     at android.os.Looper.loop(Looper.java:137)
09-19 11:15:43.083: E/AndroidRuntime(6202):     at android.app.ActivityThread.main(ActivityThread.java:5041)
09-19 11:15:43.083: E/AndroidRuntime(6202):     at java.lang.reflect.Method.invokeNative(Native Method)
09-19 11:15:43.083: E/AndroidRuntime(6202):     at java.lang.reflect.Method.invoke(Method.java:511)
09-19 11:15:43.083: E/AndroidRuntime(6202):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
09-19 11:15:43.083: E/AndroidRuntime(6202):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
09-19 11:15:43.083: E/AndroidRuntime(6202):     at dalvik.system.NativeStart.main(Native Method)
09-19 11:15:43.083: E/AndroidRuntime(6202): Caused by: java.lang.NullPointerException
09-19 11:15:43.083: E/AndroidRuntime(6202):     at cz.bakalari.bakalari.XML_Parser.getValue(XML_Parser.java:112)
09-19 11:15:43.083: E/AndroidRuntime(6202):     at cz.bakalari.bakalari.ParseActivity.onCreate(ParseActivity.java:45)
09-19 11:15:43.083: E/AndroidRuntime(6202):     at android.app.Activity.performCreate(Activity.java:5104)
09-19 11:15:43.083: E/AndroidRuntime(6202):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
09-19 11:15:43.083: E/AndroidRuntime(6202):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
09-19 11:15:43.083: E/AndroidRuntime(6202):     ... 11 more

这是我的活动：

public class ParseActivity extends Activity {



    static final String KEY_XML = "xml";

    static final String KEY_VERZE = "verze";
    static final String KEY_BKTYP = "bktyp";
    static final String KEY_STATUS = "status";
    static final String KEY_UTYP = "utyp";


    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_parse);

        XML_Parser parser = new XML_Parser();
        String xml = "<xml><verze>1.0</verze><bktyp>LOGIN</bktyp><status>OK</status><utyp>R</utyp></xml>";

        Document doc = parser.getDomElement(xml);

        NodeList nl = doc.getElementsByTagName(KEY_XML);
        Element e = (Element) nl.item(1);



        TextView parseview1 = (TextView) findViewById(R.id.parseview1);
        TextView parseview2 = (TextView) findViewById(R.id.parseview2);
        TextView parseview3 = (TextView) findViewById(R.id.parseview3);

        parseview1.setText(parser.getValue(e,KEY_VERZE));
        parseview2.setText(parser.getValue(e,KEY_BKTYP));
        parseview3.setText(parser.getValue(e,KEY_STATUS));



        };
    }

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你能看到那个问题吗？我是android开发新手，所以我需要一些简单的答案。

NodeList.item在NodeList中的索引位置返回node，如果不是有效的索引，则返回null

您的xml只有一个元素“xml”

yoyr节点列表大小为1

试着替换

Element e = (Element) nl.item(1);

到

---

一个简单的问题。XML_解析器中的第112行是什么？是线路引起了问题。非常感谢。这就是我需要的。

NodeList nl = doc.getElementsByTagName(KEY_XML);

Element e = (Element) nl.item(1);

Element e = (Element) nl.item(0);