我正在使用拉动来刷新库:https://github.com/erikwt/PullToRefresh-ListView
Logcat 给了我 NullPointerExcetpion (我想是在第 77 行)。 请帮忙，我很乐意解决这个问题。
我认为问题出在阵列、适配器上。
更新1
我将 xml 文件 id 更改为: android:id="@+id/list" 我也在java文件中正确地更改了它。 现在它显示一个新错误:
您的内容必须有一个 id 属性为“android.R.id.list”的 ListView
05-25 16:17:32.730: D/dalvikvm(29170): GC_FOR_ALLOC freed 65K, 20% free 8477K/10508K, paused 16ms, total 16ms
05-25 16:17:32.730: I/dalvikvm-heap(29170): Grow heap (frag case) to 13.708MB for 3686416-byte allocation
05-25 16:17:32.745: D/dalvikvm(29170): GC_FOR_ALLOC freed <1K, 15% free 12077K/14112K, paused 12ms, total 12ms
05-25 16:17:32.855: D/dalvikvm(29170): GC_FOR_ALLOC freed <1K, 15% free 12076K/14112K, paused 10ms, total 10ms
05-25 16:17:32.855: I/dalvikvm-heap(29170): Grow heap (frag case) to 27.771MB for 14745616-byte allocation
05-25 16:17:32.870: D/dalvikvm(29170): GC_FOR_ALLOC freed 0K, 8% free 26476K/28516K, paused 13ms, total 13ms
05-25 16:17:32.975: D/AbsListView(29170): Get MotionRecognitionManager
05-25 16:17:32.985: D/ProgressBar(29170): setProgress = 0
05-25 16:17:32.985: D/ProgressBar(29170): setProgress = 0, fromUser = false
05-25 16:17:32.985: D/ProgressBar(29170): mProgress = 0mIndeterminate = false, mMin = 0, mMax = 100
05-25 16:17:32.995: D/AndroidRuntime(29170): Shutting down VM
05-25 16:17:32.995: W/dalvikvm(29170): threadid=1: thread exiting with uncaught exception (group=0x42466700)
05-25 16:17:33.000: E/AndroidRuntime(29170): FATAL EXCEPTION: main
05-25 16:17:33.000: E/AndroidRuntime(29170): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.scapp2014.seoul.zeisler.tripathi/com.scapp2014.seoul.zeisler.tripathi.parsingXML}: java.lang.RuntimeException: Your content must have a ListView whose id attribute is 'android.R.id.list'
05-25 16:17:33.000: E/AndroidRuntime(29170): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2305)
05-25 16:17:33.000: E/AndroidRuntime(29170): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2359)
05-25 16:17:33.000: E/AndroidRuntime(29170): at android.app.ActivityThread.access$700(ActivityThread.java:165)
05-25 16:17:33.000: E/AndroidRuntime(29170): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1326)
05-25 16:17:33.000: E/AndroidRuntime(29170): at android.os.Handler.dispatchMessage(Handler.java:99)
05-25 16:17:33.000: E/AndroidRuntime(29170): at android.os.Looper.loop(Looper.java:176)
05-25 16:17:33.000: E/AndroidRuntime(29170): at android.app.ActivityThread.main(ActivityThread.java:5455)
05-25 16:17:33.000: E/AndroidRuntime(29170): at java.lang.reflect.Method.invokeNative(Native Method)
05-25 16:17:33.000: E/AndroidRuntime(29170): at java.lang.reflect.Method.invoke(Method.java:525)
05-25 16:17:33.000: E/AndroidRuntime(29170): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1209)
05-25 16:17:33.000: E/AndroidRuntime(29170): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1025)
05-25 16:17:33.000: E/AndroidRuntime(29170): at dalvik.system.NativeStart.main(Native Method)
05-25 16:17:33.000: E/AndroidRuntime(29170): Caused by: java.lang.RuntimeException: Your content must have a ListView whose id attribute is 'android.R.id.list'
05-25 16:17:33.000: E/AndroidRuntime(29170): at android.app.ListActivity.onContentChanged(ListActivity.java:243)
05-25 16:17:33.000: E/AndroidRuntime(29170): at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:364)
05-25 16:17:33.000: E/AndroidRuntime(29170): at android.app.Activity.setContentView(Activity.java:1956)
05-25 16:17:33.000: E/AndroidRuntime(29170): at com.scapp2014.seoul.zeisler.tripathi.parsingXML.onCreate(parsingXML.java:44)
05-25 16:17:33.000: E/AndroidRuntime(29170): at android.app.Activity.performCreate(Activity.java:5372)
05-25 16:17:33.000: E/AndroidRuntime(29170): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1104)
05-25 16:17:33.000: E/AndroidRuntime(29170): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2267)
05-25 16:17:33.000: E/AndroidRuntime(29170): ... 11 more
main.xml:
xmlParsing:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#ffffff" >
<ImageView
android:id="@+id/imageView1"
android:layout_width="match_parent"
android:layout_height="60dp"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:scaleType="fitXY"
android:src="@drawable/header" />
<!-- Main ListView
Always give id value as list(@android:id/list)
-->
<eu.erikw.PullToRefreshListView
android:id="@+id/list"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_below="@+id/imageView1"
android:listSelector="@drawable/list_selector"
android:dividerHeight="1dp"
android:divider="#b5b4b4" />
</RelativeLayout>
package com.scapp2014.seoul.zeisler.tripathi;
public class parsingXML extends ListActivity {
// All static variables
static final String URL = "http://pipes.yahoo.com/pipes/pipe.run?_id=02df7ff302bb81e1944ad00f28a6a3b3&_render=rss";
// XML node keys
static final String KEY_ITEM = "item"; // parent node
static final String KEY_TITLE = "title";
static final String KEY_AUTHOR = "author";
static final String KEY_DESC = "description";
static final String KEY_DATE = "pubDate";
private PullToRefreshListView listView;
ArrayList<HashMap<String, String>> menuItems;
@SuppressLint("NewApi")
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
listView = (PullToRefreshListView) findViewById(R.id.list);
listView.setOnRefreshListener(new OnRefreshListener() {
@Override
public void onRefresh() {
listView.postDelayed(new Runnable() {
@Override
public void run() {
listView.onRefreshComplete();
}
}, 50);
}
});
StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);
ArrayList<HashMap<String, String>> menuItems = new ArrayList<HashMap<String, String>>();
XMLParser parser = new XMLParser();
String xml = parser.getXmlFromUrl(URL); // getting XML
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_TITLE, parser.getValue(e, KEY_TITLE) );
map.put(KEY_AUTHOR, parser.getValue(e, KEY_AUTHOR)) ;
map.put(KEY_DESC, parser.getValue(e, KEY_DESC) + "\n");
map.put(KEY_DATE, parser.getValue(e, KEY_DATE) );
// adding HashList to ArrayList
menuItems.add(map);
}
// Adding menuItems to ListView
ListAdapter adapter = new SimpleAdapter(this, menuItems,
R.layout.list,
new String[] { KEY_TITLE, KEY_DESC, KEY_AUTHOR, KEY_DATE }, new int[] {
R.id.title, R.id.description, R.id.author, R.id.date });
setListAdapter(adapter);
// selecting single ListView item
ListView lv = getListView();
lv.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
// getting values from selected ListItem
String name = ((TextView) view.findViewById(R.id.title)).getText().toString();
String author = ((TextView) view.findViewById(R.id.author)).getText().toString();
String description = ((TextView) view.findViewById(R.id.description)).getText().toString();
String date = ((TextView) view.findViewById(R.id.date)).getText().toString();
// Starting new intent
Intent in = new Intent(getApplicationContext(), singleGUI.class);
in.putExtra(KEY_TITLE, name);
in.putExtra(KEY_DESC, description);
in.putExtra(KEY_AUTHOR, author);
in.putExtra(KEY_DATE, date);
startActivity(in);
}
});
} // end of main
}
最佳答案
如果你使用listActivity，你必须像这样改变XML中listView的id:
android:id="@android:id/list"
在你的 Activity 中你会得到像 SteD 所说的列表:
listview = getListView();
关于java - Android ListView NullPointerException 使用 pulldowntoRefresh？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/23852471/