当用户点击viewpager中strings.xml中的某个项目时，我正尝试从ListView中提取字符串。但是，当我尝试从NullPointerException调用字符串时，我得到strings.xml。例如，我构造了一个字符串“VitaminA_definition”，它对应于strings.xml中的同名字符串。我已经检查过以确保我的字符串格式化了＆amp;拼写正确。
为什么我会收到NullPointerException？
case 1:
resId = (R.layout.reference_layout);
view = inflater.inflate(resId, null);
vitamins_ListView = (IndexableListView)view.findViewById(R.id.herbList);
vitaminsListresource = res.getStringArray(R.array.vitaminlist);
vitaminsItems = new ArrayList<String>();
Collections.addAll(vitaminsItems, vitaminsListresource);
Collections.sort(vitaminsItems);
ArrayAdapter<String> vitamins_adapter = new CustomListAdapter(ReferenceActivity.this, R.layout.list_item_vitamins);
for (int i=0; i<vitaminsItems.size();i++)
vitamins_adapter.add(vitaminsItems.get(i));
vitamins_ListView.setAdapter(vitamins_adapter);
vitamins_ListView.setFastScrollEnabled(true);
vitamins_ListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, final View view, int position, long id) {
View toolbar = view.findViewById(R.id.vitamin_toolbar);
String vitamin_definition = vitamins_ListView.getItemAtPosition(position).toString() + "_definition";
String new_vitamin_definition = vitamin_definition.replaceAll("\\s+", "").replace("'", "").replace(".", "").replace("(", "").replace(")", "");
Log.e("vitamin_definition result", new_vitamin_definition);
String vitamin_deficiency = vitamins_ListView.getItemAtPosition(position).toString() + "_deficiency";
String new_vitamin_deficiency = vitamin_deficiency.replaceAll("\\s+", "").replace("'", "").replace(".", "").replace("(", "").replace(")", "");
Log.e("vitamin_defieciency result", new_vitamin_deficiency);
String vitamin_herbs = vitamins_ListView.getItemAtPosition(position).toString() + "_herbs";
String new_vitamin_herbs = vitamin_herbs.replaceAll("\\s+", "").replace("'", "").replace(".", "").replace("(", "").replace(")", "");
Log.e("vitamin_herbs result", new_vitamin_herbs);
String vitamin_foods = vitamins_ListView.getItemAtPosition(position).toString() + "_foods";
String new_vitamin_foods = vitamin_foods.replaceAll("\\s+", "").replace("'", "").replace(".", "").replace("(", "").replace(")", "");
Log.e("vitamin_foods result", new_vitamin_foods);
try{
((TextView)view.findViewById(R.id.vitamin_description)).setText("Definition: " +(ReferenceActivity.this.getResources().getIdentifier(new_vitamin_definition, "string", ReferenceActivity.this.getApplicationInfo().packageName)));
((TextView)view.findViewById(R.id.vitamin_deficiency)).setText("Deficiency: " +(ReferenceActivity.this.getResources().getIdentifier(new_vitamin_deficiency, "string", ReferenceActivity.this.getApplicationInfo().packageName)));
((TextView)view.findViewById(R.id.vitamin_herbs)).setText("Herbs: " +(ReferenceActivity.this.getResources().getIdentifier(new_vitamin_herbs, "string", ReferenceActivity.this.getApplicationInfo().packageName)));
((TextView)view.findViewById(R.id.vitamin_foods)).setText("Foods: " +(ReferenceActivity.this.getResources().getIdentifier(new_vitamin_foods, "string", ReferenceActivity.this.getApplicationInfo().packageName)));
}catch(Exception e){
Log.e("Vitamin Info Error", "Error loading Vitamin Info >> " + e.getMessage() + " //" + e.toString());
//String Check. All strings working here
Log.e("String Test", getResources().getString(R.string.VitaminA_definition).toString());
Log.e("String Test", getResources().getString(R.string.VitaminA_deficiency).toString());
Log.e("String Test", getResources().getString(R.string.VitaminA_herbs).toString());
Log.e("String Test", getResources().getString(R.string.VitaminA_foods).toString());
}
// Creating the expand animation for the item
ExpandAnimation expandAni = new ExpandAnimation(toolbar, 500);
// Start the animation on the toolbar
toolbar.startAnimation(expandAni);
}
});
((ViewPager) collection).addView(view, 0);
return view;
的strings.xml
<string-array name="vitaminlist">
<item>Vitamin A</item>
<item>Vitmain B1 (Thiamine)</item>
<item>Vitmain B2 (Riboflavin)</item>
<item>Vitmain B3 (Niacin)</item>
<item>Vitmain B4 </item>
<item>Vitmain B5 (Pantothenic Acid)</item>
<item>Vitmain B6 (Pyridoxine)</item>
<item>Vitmain B12 (Cyanocobalamin, Cobalt)</item>
<item>Vitmain B13 (Orotic Acid)</item>
<item>Vitmain B13 (Pangamic Acid)</item>
<item>Vitamin C (Asorbic Acid)</item>
<item>Vitamin D (Ergosterol)</item>
<item>Vitmain E</item>
<item>Vitamin F (Fatty Acid)</item>
<item>Vitamin G</item>
<item>Vitamin H (Biotin)</item>
<item>Vitamin K</item>
<item>Vitamin L</item>
<item>Vitamin P (Bioflavonoids)</item>
<item>Vitamin P (Rutin)</item>
<item>Vitamin T</item>
<item>Vitamin U</item>
<item>Choline</item>
<item>Folic Acid (Inositol and Vitamin B)</item>
<item>PABA(Para-Amino-Benzino-Acid)</item>
</string-array>
<string name="VitaminA_definition">Maintains health of tissue, hair; builds resistance, helps eyes, nasal passage, lungs, stress, etc.</string>
<string name="VitaminA_deficiency">Eye inflammation, weak vision, respiratory problems, skin diseases, poor sense of taste and smell, get infections easily, teeth and gum problems.</string>
<string name="VitaminA_herbs">Alfalfa, Burdock, Comfrey, Dandelion, Eyebright, Okra Pods, Paprika, Parsley, Rosehip, Watercress.</string>
<string name="VitaminA_foods">Carrots, Green Leafy Vegetables, Melons, Tomatoes, Yams, Fruits.</string>
这是logcat：
06-17 08:53:02.328: E/vitamin_definition result(13309): VitaminA_definition
06-17 08:53:02.328: E/vitamin_defieciency result(13309): VitaminA_deficiency
06-17 08:53:02.336: E/vitamin_herbs result(13309): VitaminA_herbs
06-17 08:53:02.336: E/vitamin_foods result(13309): VitaminA_foods
06-17 08:53:02.336: W/System.err(13309): java.lang.NullPointerException
06-17 08:53:02.344: W/System.err(13309): at com.bryanjrichardson.VITALITY.ReferenceActivity$MyPagerAdapter$2.onItemClick(ReferenceActivity.java:398)
06-17 08:53:02.344: W/System.err(13309): at android.widget.AdapterView.performItemClick(AdapterView.java:292)
06-17 08:53:02.344: W/System.err(13309): at android.widget.AbsListView.performItemClick(AbsListView.java:1082)
06-17 08:53:02.344: W/System.err(13309): at android.widget.AbsListView$PerformClick.run(AbsListView.java:2635)
06-17 08:53:02.344: W/System.err(13309): at android.widget.AbsListView$1.run(AbsListView.java:3306)
06-17 08:53:02.344: W/System.err(13309): at android.os.Handler.handleCallback(Handler.java:605)
06-17 08:53:02.344: W/System.err(13309): at android.os.Handler.dispatchMessage(Handler.java:92)
06-17 08:53:02.344: W/System.err(13309): at android.os.Looper.loop(Looper.java:137)
06-17 08:53:02.344: W/System.err(13309): at android.app.ActivityThread.main(ActivityThread.java:4722)
06-17 08:53:02.344: W/System.err(13309): at java.lang.reflect.Method.invokeNative(Native Method)
06-17 08:53:02.344: W/System.err(13309): at java.lang.reflect.Method.invoke(Method.java:511)
06-17 08:53:02.352: W/System.err(13309): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:787)
06-17 08:53:02.352: W/System.err(13309): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:554)
06-17 08:53:02.352: W/System.err(13309): at dalvik.system.NativeStart.main(Native Method)
06-17 08:53:02.352: E/Vitamin Info Error(13309): Error loading Vitamin Info >> null //java.lang.NullPointerException