我目前正在获取空指针异常，只要我的listview中有6个或更多项目＆amp;＆amp;当我尝试点击任何listview行。注意：当我点击包含少于6个项目的listview行时，一切都按预期工作。
任何帮助都会很棒我已经被困在这个问题很长一段时间了= \（大约一个月）
12-16 04:11:34.309: W/dalvikvm(2028): threadid=1: thread exiting with uncaught exception (group=0x95b62648)
12-16 04:11:34.309: E/AndroidRuntime(2028): FATAL EXCEPTION: main
12-16 04:11:34.309: E/AndroidRuntime(2028): java.lang.NullPointerException
12-16 04:11:34.309: E/AndroidRuntime(2028): at android.widget.ArrayAdapter.createViewFromResource(ArrayAdapter.java:394)
12-16 04:11:34.309: E/AndroidRuntime(2028): at android.widget.ArrayAdapter.getView(ArrayAdapter.java:362)
12-16 04:11:34.309: E/AndroidRuntime(2028): at com.android.internal.app.AlertController$AlertParams$1.getView(AlertController.java:879)
12-16 04:11:34.309: E/AndroidRuntime(2028): at android.widget.AbsListView.obtainView(AbsListView.java:2161)
12-16 04:11:34.309: E/AndroidRuntime(2028): at android.widget.ListView.measureHeightOfChildren(ListView.java:1247)
12-16 04:11:34.309: E/AndroidRuntime(2028): at android.widget.ListView.onMeasure(ListView.java:1159)
12-16 04:11:34.309: E/AndroidRuntime(2028): at android.view.View.measure(View.java:15848)
12-16 04:11:34.309: E/AndroidRuntime(2028): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5012)
12-16 04:11:34.309: E/AndroidRuntime(2028): at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1404)
12-16 04:11:34.309: E/AndroidRuntime(2028): at android.widget.LinearLayout.measureVertical(LinearLayout.java:695)
12-16 04:11:34.309: E/AndroidRuntime(2028): at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
12-16 04:11:34.309: E/AndroidRuntime(2028): at android.view.View.measure(View.java:15848)
12-16 04:11:34.309: E/AndroidRuntime(2028): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5012)
12-16 04:11:34.309: E/AndroidRuntime(2028): at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1404)
12-16 04:11:34.309: E/AndroidRuntime(2028): at android.widget.LinearLayout.measureVertical(LinearLayout.java:695)
12-16 04:11:34.309: E/AndroidRuntime(2028): at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
12-16 04:11:34.309: E/AndroidRuntime(2028): at android.view.View.measure(View.java:15848)
12-16 04:11:34.309: E/AndroidRuntime(2028): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5012)
12-16 04:11:34.309: E/AndroidRuntime(2028): at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
12-16 04:11:34.309: E/AndroidRuntime(2028): at android.view.View.measure(View.java:15848)
12-16 04:11:34.309: E/AndroidRuntime(2028): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5012)
12-16 04:11:34.309: E/AndroidRuntime(2028): at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
12-16 04:11:34.309: E/AndroidRuntime(2028): at android.view.View.measure(View.java:15848)
12-16 04:11:34.309: E/AndroidRuntime(2028): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5012)
12-16 04:11:34.309: E/AndroidRuntime(2028): at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
12-16 04:11:34.309: E/AndroidRuntime(2028): at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2189)
12-16 04:11:34.309: E/AndroidRuntime(2028): at android.view.View.measure(View.java:15848)
12-16 04:11:34.309: E/AndroidRuntime(2028): at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1905)
12-16 04:11:34.309: E/AndroidRuntime(2028): at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1079)
12-16 04:11:34.309: E/AndroidRuntime(2028): at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1284)
12-16 04:11:34.309: E/AndroidRuntime(2028): at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1004)
12-16 04:11:34.309: E/AndroidRuntime(2028): at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5481)
12-16 04:11:34.309: E/AndroidRuntime(2028): at android.view.Choreographer$CallbackRecord.run(Choreographer.java:749)
12-16 04:11:34.309: E/AndroidRuntime(2028): at android.view.Choreographer.doCallbacks(Choreographer.java:562)
12-16 04:11:34.309: E/AndroidRuntime(2028): at android.view.Choreographer.doFrame(Choreographer.java:532)
12-16 04:11:34.309: E/AndroidRuntime(2028): at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:735)
12-16 04:11:34.309: E/AndroidRuntime(2028): at android.os.Handler.handleCallback(Handler.java:730)
12-16 04:11:34.309: E/AndroidRuntime(2028): at android.os.Handler.dispatchMessage(Handler.java:92)
12-16 04:11:34.309: E/AndroidRuntime(2028): at android.os.Looper.loop(Looper.java:137)
12-16 04:11:34.309: E/AndroidRuntime(2028): at android.app.ActivityThread.main(ActivityThread.java:5103)
12-16 04:11:34.309: E/AndroidRuntime(2028): at java.lang.reflect.Method.invokeNative(Native Method)
12-16 04:11:34.309: E/AndroidRuntime(2028): at java.lang.reflect.Method.invoke(Method.java:525)
12-16 04:11:34.309: E/AndroidRuntime(2028): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
12-16 04:11:34.309: E/AndroidRuntime(2028): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
12-16 04:11:34.309: E/AndroidRuntime(2028): at dalvik.system.NativeStart.main(Native Method)
我的代码我认为我收到此错误的原因是
private class MyListAdapter extends ArrayAdapter<Item>
{
public MyListAdapter(){
//Important 4 SO: customerItems is an arraylist of <Item> Objects
super（UserOrderMenu.this，R.layout.itemview，customerItems）; //这是错的？ }
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View itemView = convertView;
if(itemView == null){ //makes sure we have a view to work with
itemView = getLayoutInflater().inflate(R.layout.itemview,parent,false);
} else{
itemView = convertView;
}
//find the item to work with. using item class and customerItem ArrayList
final Item currentItem = customerItems.get(position);
ImageView imageview = (ImageView) itemView.findViewById(R.id.imageButtonTrashCan);
imageview.setClickable(true);
imageview.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
remove(currentItem);
notifyDataSetChanged(); //this notifies the Arrayadapter to update
float t1price, t2price, t3price, t4price, t5price;
System.out.println(currentItem.getTopping1Used());
if(currentItem.getTopping1Used()){
t1price = currentItem.getTop1P();
}else
t1price = 0;
if(currentItem.getTopping2Used()){
t2price = currentItem.getTop2P();
}else
t2price =0;
if(currentItem.getTopping3Used()){
t3price = currentItem.getTop3P();
}else
t3price = 0;
if(currentItem.getTopping4Used()){
t4price = currentItem.getTop4P();
}else
t4price =0;
if(currentItem.getTopping5Used()){
t5price = currentItem.getTop5P();
}else
t5price =0;
findTotalPrice(-t1price,-t2price,-t3price,-t4price,-t5price,true);
findTotalPrice(-currentItem.getItemP());
}
});
TextView n = (TextView) itemView.findViewById(R.id.tvItemName);
n.setText(currentItem.getItem().toString());
// then currentItem.getTop1P();
TextView p = (TextView) itemView.findViewById(R.id.tvItemPrice);
p.setText(String.valueOf(currentItem.getItemP()));
return itemView;
}
}//end of MyListAdapter Class
private void populateListView(){ //this is how to add an item to ListView
customerItems.removeAll(Collections.singleton(null)); //remove later
customerItems.removeAll(Arrays.asList(null,""));
ArrayAdapter<Item> adapter;
try{
adapter = new MyListAdapter();
ListView list = (ListView) findViewById(R.id.listView1);
list.setAdapter(adapter);
}catch(Exception e){
}
}
Item.java：
public class Item {
private String item="none";
private float itemP=0;
private String top1="none";
private float top1P=0;
private String top2="none";
private float top2P=0;
private String top3="none";
private float top3P=0;
private String top4="none";
private float top4P=0;
private String top5="none";
private float top5P=0;
private boolean topping1used = false;
private boolean topping2used = false;
private boolean topping3used = false;
private boolean topping4used = false;
private boolean topping5used = false;
public Item(){
super();
}
public Item(String item, float itemP){
super();
this.item = item;
this.itemP = itemP;
}
public Item(String item, float itemP,String top1,float top1P,String top2,float top2P,String top3,
float top3P,String top4,float top4P,String top5,float top5P)
{
super();
this.item = item;
this.itemP = itemP;
//this is a price dont have to worry about it
this.top1 = top1;
this.top1P = top1P;
this.top2 = top2;
this.top2P = top2P;
this.top3 = top3;
this.top3P = top3P;
this.top4 = top4;
this.top4P = top4P;
this.top5 = top5;
this.top5P = top5P;
}
public Item(boolean t1, boolean t2, boolean t3, boolean t4, boolean t5){
super();
this.topping1used = t1;
this.topping2used = t2;
this.topping3used = t3;
this.topping4used = t4;
this.topping5used = t5;
}
//set
public void setTopping1used(boolean topping1used) {
this.topping1used = topping1used;
}
public void setTopping2used(boolean topping2used) {
this.topping2used = topping2used;
}
public void setTopping3used(boolean topping3used) {
this.topping3used = topping3used;
}
public void setTopping4used(boolean topping4used) {
this.topping4used = topping4used;
}
public void setTopping5used(boolean topping5used) {
this.topping5used = topping5used;
}
//get
public String getItem() {
return item;
}
public float getItemP() {
return itemP;
}
public String getTop1() {
return top1;
}
public float getTop1P() {
return top1P;
}
public String getTop2() {
return top2;
}
public float getTop2P() {
return top2P;
}
public String getTop3() {
return top3;
}
public float getTop3P() {
return top3P;
}
public String getTop4() {
return top4;
}
public float getTop4P() {
return top4P;
}
public String getTop5() {
return top5;
}
public float getTop5P() {
return top5P;
}
public boolean getTopping1Used(){
return topping1used;
}
public boolean getTopping2Used(){
return topping2used;
}
public boolean getTopping3Used(){
return topping3used;
}
public boolean getTopping4Used(){
return topping4used;
}
public boolean getTopping5Used(){
return topping5used;
}
}//end of Item class
private void populateList(String item, float price,String t1n, float t1p, String t2n, float t2p,
String t3n,float t3p, String t4n, float t4p, String t5n, float t5p)
{
customerItems.add(new Item(item,price,t1n,t1p,t2n,t2p,t3n,t3p,t4n,t4p,t5n,t5p));
populateListView();
}
private void populateListView（）{//这是如何将项添加到ListView customerItems.removeAll（Collections.singleton（空））; //稍后删除 customerItems.removeAll（Arrays.asList（NULL， “”））; ArrayAdapter适配器;
try{
adapter = new MyListAdapter();
ListView list = (ListView) findViewById(R.id.listView1);
list.setAdapter(adapter);
}catch(Exception e){
}
}
答案 0 :(得分：2)
1）您的编码标准不好，我建议您改进一下
2）你没有正确地提到这个问题而且你粘贴的代码评论太多了，因为很难知道你想要达到的目的，或者你是否有目的地粘贴SO。
3）你的getView（）方法实现错误，请检查以下正确的方法：
if (convertView == null)
{
mLayoutInflater = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
convertView = mLayoutInflater.inflate(R.layout.Your_Row_XML_File, null);
viewHolder = new ViewHolder();
viewHolder.textView1 = (TextView) convertView.findViewById(R.id.textView1_in_row_xml_inflated_as_above);
convertView.setTag(viewHolder);
}
else
{
viewHolder = (ViewHolder) convertView.getTag();
}
viewHolder.textView1.setText("Any string value");
而您的ViewHolder包含xml文件中视图的视图声明：
private final class ViewHolder
{
public TextView textView1;
public TextView textView2; // if any and add views like this
}
参考示例和Android文档以清除相同的理解，这将是很好的，并为您的代码提供良好的基础。
希望它有所帮助。
答案 1 :(得分：1)
好的，所以在永远调试我的程序后，我终于找到了解决方案。我将在这里试着清楚地总结一下。
问题：当我从我的Listview调用Android的AlertDialog（多个选项项！）时，它会崩溃我的程序。
解决方案：而不是使用Androids AlertDialog进行多项选择。我必须创建自己的多项选择项的自定义版本。然后，当我点击列表视图激活alertdialog时，一切都很好。
如果您从列表视图中调用多选警报对话框，则表示您遇到了android.widget.ArrayAdapter.createViewFromResource（ArrayAdapter.java:394）的空指针异常。然后尝试创建自己的自定义多项选择！
请原谅我的重复希望将来可能对某人有所帮助。
答案 2 :(得分：0)
试试这个：
private class MyListAdapter extends BaseAdapter
{
Context mContext;
List<Item> mItem;
public MyListAdapter(Context context,List<Item> item){
super(context, item);
this.mContext =context;
this.mItem=item;
}
@Override
public int getCount() {
return item.size();
}
@Override
public Object getItem(int position)
return position;
}
@Override
public long getItemId(int position) {
// TODO Auto-generated method stub
return position;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View itemView = convertView;
if(itemView == null){
itemView = getLayoutInflater().inflate(R.layout.itemview, null);
}
final Item currentItem = customerItems.get(position);
ImageView imageview = (ImageView) itemView.findViewById(R.id.imageButtonTrashCan);
imageview.setClickable(true);
imageview.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
}
});
TextView n = (TextView) itemView.findViewById(R.id.tvItemName);
n.setText(currentItem.getItem.toString());
TextView p = (TextView) itemView.findViewById(R.id.tvItemPrice);
p.setText(String.valueOf(currentItem.getItemP()));
return itemView;
}
}
用于设置列表视图：列表是您的项目列表;
MyListAdapter adapter = new MyListAdapter(this, list);
ListView list = (ListView) findViewById(R.id.listView1);
list.setAdapter(adapter);
试试这个，如果不起作用而不是评论：