[英]ListView Item OnItemClick crashing in ListView Adapter Class
我一直在嘗試使列表視圖工作一段時間,我只是將偵聽器從onClick更改為onItemClick以更好地處理listview項目,但是該應用程序再次崩潰,我的代碼在下面,對您的幫助將不勝感激。
類:
public class ListViewAdapterProduct extends BaseAdapter {
Context mContext;
ListView listView = (ListView) findViewById(R.id.listview1);
listView.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View v, int position, long id){
Resources res = mContext.getResources();
productTitleArray = res.getStringArray(R.array.titles_product);
for (String productTitle : productTitleArray)
{
if(productTitle.equals("productOne"))
{
Log.d("Msg", "Found");
}
else
{
Log.d("Msg", "Not Found");
}
}
}
});
我以前的帖子:
單擊ListView中的項目時,比較Java類中的XML字符串
Logcat :
03-30 16:40:39.027: E/AndroidRuntime(811): FATAL EXCEPTION: main
03-30 16:40:39.027: E/AndroidRuntime(811): java.lang.NullPointerException
03-30 16:40:39.027: E/AndroidRuntime(811): at com.twostarii.test.ListViewAdapterproduct.getView(ListViewAdapterproduct.java:91)
03-30 16:40:39.027: E/AndroidRuntime(811): at android.widget.AbsListView.obtainView(AbsListView.java:2159)
03-30 16:40:39.027: E/AndroidRuntime(811): at android.widget.ListView.makeAndAddView(ListView.java:1831)
03-30 16:40:39.027: E/AndroidRuntime(811): at android.widget.ListView.fillDown(ListView.java:674)
03-30 16:40:39.027: E/AndroidRuntime(811): at android.widget.ListView.fillFromTop(ListView.java:735)
03-30 16:40:39.027: E/AndroidRuntime(811): at android.widget.ListView.layoutChildren(ListView.java:1652)
03-30 16:40:39.027: E/AndroidRuntime(811): at android.widget.AbsListView.onLayout(AbsListView.java:1994)
03-30 16:40:39.027: E/AndroidRuntime(811): at android.view.View.layout(View.java:14008)
03-30 16:40:39.027: E/AndroidRuntime(811): at android.view.ViewGroup.layout(ViewGroup.java:4373)
03-30 16:40:39.027: E/AndroidRuntime(811): at android.widget.RelativeLayout.onLayout(RelativeLayout.java:1021)
03-30 16:40:39.027: E/AndroidRuntime(811): at android.view.View.layout(View.java:14008)
03-30 16:40:39.027: E/AndroidRuntime(811): at android.view.ViewGroup.layout(ViewGroup.java:4373)
03-30 16:40:39.027: E/AndroidRuntime(811): at android.widget.FrameLayout.onLayout(FrameLayout.java:448)
03-30 16:40:39.027: E/AndroidRuntime(811): at android.view.View.layout(View.java:14008)
03-30 16:40:39.027: E/AndroidRuntime(811): at android.view.ViewGroup.layout(ViewGroup.java:4373)
03-30 16:40:39.027: E/AndroidRuntime(811): at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1663)
03-30 16:40:39.027: E/AndroidRuntime(811): at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1521)
03-30 16:40:39.027: E/AndroidRuntime(811): at android.widget.LinearLayout.onLayout(LinearLayout.java:1434)
03-30 16:40:39.027: E/AndroidRuntime(811): at android.view.View.layout(View.java:14008)
03-30 16:40:39.027: E/AndroidRuntime(811): at android.view.ViewGroup.layout(ViewGroup.java:4373)
03-30 16:40:39.027: E/AndroidRuntime(811): at android.widget.FrameLayout.onLayout(FrameLayout.java:448)
03-30 16:40:39.027: E/AndroidRuntime(811): at android.view.View.layout(View.java:14008)
03-30 16:40:39.027: E/AndroidRuntime(811): at android.view.ViewGroup.layout(ViewGroup.java:4373)
03-30 16:40:39.027: E/AndroidRuntime(811): at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:1892)
03-30 16:40:39.027: E/AndroidRuntime(811): at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1711)
03-30 16:40:39.027: E/AndroidRuntime(811): at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:989)
03-30 16:40:39.027: E/AndroidRuntime(811): at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4351)
03-30 16:40:39.027: E/AndroidRuntime(811): at android.view.Choreographer$CallbackRecord.run(Choreographer.java:749)
03-30 16:40:39.027: E/AndroidRuntime(811): at android.view.Choreographer.doCallbacks(Choreographer.java:562)
03-30 16:40:39.027: E/AndroidRuntime(811): at android.view.Choreographer.doFrame(Choreographer.java:532)
03-30 16:40:39.027: E/AndroidRuntime(811): at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:735)
03-30 16:40:39.027: E/AndroidRuntime(811): at android.os.Handler.handleCallback(Handler.java:725)
03-30 16:40:39.027: E/AndroidRuntime(811): at android.os.Handler.dispatchMessage(Handler.java:92)
03-30 16:40:39.027: E/AndroidRuntime(811): at android.os.Looper.loop(Looper.java:137)
03-30 16:40:39.027: E/AndroidRuntime(811): at android.app.ActivityThread.main(ActivityThread.java:5041)
03-30 16:40:39.027: E/AndroidRuntime(811): at java.lang.reflect.Method.invokeNative(Native Method)
03-30 16:40:39.027: E/AndroidRuntime(811): at java.lang.reflect.Method.invoke(Method.java:511)
03-30 16:40:39.027: E/AndroidRuntime(811): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
03-30 16:40:39.027: E/AndroidRuntime(811): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
03-30 16:40:39.027: E/AndroidRuntime(811): at dalvik.system.NativeStart.main(Native Method)
活動:
public class MainActivityproduct extends MainActivity {
ListView list;
ListViewAdapterproduct adapter;
EditText editsearch;
String[] position;
String[] productTitles;
String[] productDescriptions;
int[] images={
R.drawable.list_product_one,
R.drawable.list_product_two,
R.drawable.list_product_three,
};
ArrayList<ClassproductList> arraylist = new ArrayList<ClassproductList>();
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
position = new String[] { "1", "2", "3"};
Resources res = getResources();
productTitles = res.getStringArray(R.array.titles_product);
productDescriptions = res.getStringArray(R.array.descriptions_product);
list = (ListView) findViewById(R.id.listview1);
list.setAdapter(adapter);
for (int i = 0; i < position.length; i++)
{
ClassproductList wp = new ClassproductList(productTitles[i], productDescriptions[i],images[i]);
arraylist.add(wp);
}
adapter = new ListViewAdapterproduct(this, arraylist);
list.setAdapter(adapter);
editsearch = (EditText) findViewById(R.id.search);
editsearch.addTextChangedListener(new TextWatcher() {
@Override
public void afterTextChanged(Editable arg0) {
String text = editsearch.getText().toString().toLowerCase(Locale.getDefault());
adapter.filter(text);
}
@Override
public void beforeTextChanged(CharSequence arg0, int arg1,
int arg2, int arg3) {
}
public void onTextChanged(CharSequence arg0, int arg1, int arg2,
int arg3) {
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}
您在Context mContext;
有問題Context mContext;
一片空白
在您的活動中設置mContext = this;
所以mContext將是活動context
您將能夠使用資源
這是正確的代碼:
由於您已經在適配器中發送了this
,因此您需要在適配器中捕獲它
public class ListViewAdapterProduct extends BaseAdapter {
Context mContext;
ArrayList<ClassproductList> arraylist;
ListView listView = (ListView) findViewById(R.id.listview1);
//add this
public ListViewAdapterProduct (Context mContext,ArrayList<ClassproductList> arraylist)
{
this.mContext = mContext;
this.arraylist = arraylist;
}
您已經聲明了mContext,但是尚未初始化它。
您可以在適配器的構造函數中執行此操作:
public class ListViewAdapterProduct extends BaseAdapter {
Context mContext;
// the construcor that initializes the context
public ListViewAdapterProduct(Context c){
mContext = c;
}
...
但是,您發布的跟蹤表明問題出在適配器的getView()方法的第91行上。您也應該檢查該問題。
ListViewAdapterproduct.getView(ListViewAdapterproduct.java:91)
編輯:
list.setAdapter(adapter);
在這一行中,適配器為null,您沒有對其進行初始化...(將適配器設置兩次,首先設置為null)。 最好在本地定義變量,並僅在實際需要時才將其設置為類變量。 這樣一來,很難忘記初始化。
解決了 !!!
我從onItemClick(復雜地與自定義適配器一起使用)改回onClick(簡單地與自定義適配器一起使用)並應用了:
view.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View arg0) {
String mytitle=holder.title.getText().toString();
if(mytitle.equals("ProductOne")){
Intent intent1 = new Intent(mContext, ProductClass.ProductOne);
mContext.startActivity(intent1);
...
}
}
必須添加:
String mytitle=holder.title.getText().toString();
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