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項目をクリックするとアプリがクラッシュします。私のコードにはEclipseでエラーはありませんが、それが言う項目の1つをクリックすると(残念ながらアプリは動作を停止しました)、LogCatはエラーの束を吐き出し、そのうちの1つは: 02-14 04:33:20.010: E /MessageQueue-JNI(774​​): java.lang.NullPointerException. この問題を解決する方法についてのアイデアはありますか?

package com.carouseldemo.main;

import com.carouseldemo.controls.Carousel;

import com.carouseldemo.controls.CarouselAdapter; 
import com.carouseldemo.controls.CarouselAdapter.OnItemClickListener;
/**import com.carouseldemo.controls.CarouselAdapter.OnItemSelectedListener;*/
import com.carouseldemo.controls.CarouselItem;


import android.app.Activity;
import android.os.Bundle;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.MenuInflater;
import android.view.Menu;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import android.widget.Toast;




public class MainActivity extends Activity {

    /** Called when the activity is first created. */
    @Override
    public boolean onCreateOptionsMenu(Menu menu){
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.testmenu, menu);
        return true;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        Carousel carousel = (Carousel)findViewById(R.id.carousel);

        carousel.setOnItemClickListener(new OnItemClickListener(){

            public void onItemClick(CarouselAdapter<?> parent, View view,
                    int position, long id) {    
                LayoutInflater inflater = getLayoutInflater();
                View layout = inflater.inflate(R.layout.toast_layout,
                                               (ViewGroup) findViewById(R.id.toast_layout_root));

                TextView text = (TextView) layout.findViewById(R.id.selected_item);
                text.setText("This is a custom toast");

                Toast toast = new Toast(getApplicationContext());
                toast.setGravity(Gravity.CENTER_VERTICAL, 0, 0);
                toast.setDuration(Toast.LENGTH_LONG);
                toast.setView(layout);
                toast.show();


                Toast.makeText(MainActivity.this, 
                        String.format("%s has been clicked", 
                        ((CarouselItem)parent.getChildAt(position)).getName()), 
                        Toast.LENGTH_SHORT).show();z
    }



        });


       /** carousel.setOnItemSelectedListener(new OnItemSelectedListener(){

            public void onItemSelected(CarouselAdapter<?> parent, View view,
                    int position, long id) {

                final TextView txt = (TextView)(findViewById(R.id.selected_item));

                switch(position){
                case 0:
                    txt.setText("The cat (Felis catus), also known as the domestic cat or housecat to distinguish it from other felids and felines, is a small, usually furry, domesticated, carnivorous mammal that is valued by humans for its companionship and for its ability to hunt vermin and household pests. Cats have been associated with humans for at least 9,500 years, and are currently the most popular pet in the world. Owing to their close association with humans, cats are now found almost everywhere in the world.");
                    break;
                case 1:
                    txt.setText("The hippopotamus (Hippopotamus amphibius), or hippo, from the ancient Greek for \"river horse\" (ἱπποπόταμος), is a large, mostly herbivorous mammal in sub-Saharan Africa, and one of only two extant species in the family Hippopotamidae (the other is the Pygmy Hippopotamus.) After the elephant, the hippopotamus is the third largest land mammal and the heaviest extant artiodactyl.");
                    break;
                case 2:
                    txt.setText("A monkey is a primate, either an Old World monkey or a New World monkey. There are about 260 known living species of monkey. Many are arboreal, although there are species that live primarily on the ground, such as baboons. Monkeys are generally considered to be intelligent. Unlike apes, monkeys usually have tails. Tailless monkeys may be called \"apes\", incorrectly according to modern usage; thus the tailless Barbary macaque is called the \"Barbary ape\".");
                    break;
                case 3:
                    txt.setText("A mouse (plural: mice) is a small mammal belonging to the order of rodents. The best known mouse species is the common house mouse (Mus musculus). It is also a popular pet. In some places, certain kinds of field mice are also common. This rodent is eaten by large birds such as hawks and eagles. They are known to invade homes for food and occasionally shelter.");
                    break;
                case 4:
                    txt.setText("The giant panda, or panda (Ailuropoda melanoleuca, literally meaning \"black and white cat-foot\") is a bear native to central-western and south western China.[4] It is easily recognized by its large, distinctive black patches around the eyes, over the ears, and across its round body. Though it belongs to the order Carnivora, the panda's diet is 99% bamboo.");
                    break;
                case 5:
                    txt.setText("Rabbits (or, colloquially, bunnies) are small mammals in the family Leporidae of the order Lagomorpha, found in several parts of the world. There are eight different genera in the family classified as rabbits, including the European rabbit (Oryctolagus cuniculus), cottontail rabbits (genus Sylvilagus; 13 species), and the Amami rabbit (Pentalagus furnessi, an endangered species on Amami ÅŒshima, Japan)");
                    break;
                }
                            }

            public void onNothingSelected(CarouselAdapter<?> parent) {          } 


        }
        );*/

    }
     }

LogCat エラー ログ:

02-14 14:38:09.137: E/InputEventReceiver(996): Exception dispatching input event.
02-14 14:38:09.148: E/MessageQueue-JNI(996): Exception in MessageQueue callback: handleReceiveCallback
02-14 14:38:09.207: E/MessageQueue-JNI(996): java.lang.NullPointerException
02-14 14:38:09.207: E/MessageQueue-JNI(996):    at com.carouseldemo.main.MainActivity$1.onItemClick(MainActivity.java:50)
02-14 14:38:09.207: E/MessageQueue-JNI(996):    at com.carouseldemo.controls.CarouselAdapter.performItemClick(CarouselAdapter.java:261)
02-14 14:38:09.207: E/MessageQueue-JNI(996):    at com.carouseldemo.controls.Carousel.onSingleTapUp(Carousel.java:967)
02-14 14:38:09.207: E/MessageQueue-JNI(996):    at android.view.GestureDetector.onTouchEvent(GestureDetector.java:588)
02-14 14:38:09.207: E/MessageQueue-JNI(996):    at com.carouseldemo.controls.Carousel.onTouchEvent(Carousel.java:311)
02-14 14:38:09.207: E/MessageQueue-JNI(996):    at android.view.View.dispatchTouchEvent(View.java:7239)
02-14 14:38:09.207: E/MessageQueue-JNI(996):    at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2168)
02-14 14:38:09.207: E/MessageQueue-JNI(996):    at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1903)
02-14 14:38:09.207: E/MessageQueue-JNI(996):    at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2174)
02-14 14:38:09.207: E/MessageQueue-JNI(996):    at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1917)
02-14 14:38:09.207: E/MessageQueue-JNI(996):    at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2174)
02-14 14:38:09.207: E/MessageQueue-JNI(996):    at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1917)
02-14 14:38:09.207: E/MessageQueue-JNI(996):    at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2174)
02-14 14:38:09.207: E/MessageQueue-JNI(996):    at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1917)
02-14 14:38:09.207: E/MessageQueue-JNI(996):    at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2174)
02-14 14:38:09.207: E/MessageQueue-JNI(996):    at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1917)
02-14 14:38:09.207: E/MessageQueue-JNI(996):    at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2174)
02-14 14:38:09.207: E/MessageQueue-JNI(996):    at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1917)
02-14 14:38:09.207: E/MessageQueue-JNI(996):    at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:1953)
02-14 14:38:09.207: E/MessageQueue-JNI(996):    at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1405)
02-14 14:38:09.207: E/MessageQueue-JNI(996):    at android.app.Activity.dispatchTouchEvent(Activity.java:2410)
02-14 14:38:09.207: E/MessageQueue-JNI(996):    at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:1901)
02-14 14:38:09.207: E/MessageQueue-JNI(996):    at android.view.View.dispatchPointerEvent(View.java:7419)
02-14 14:38:09.207: E/MessageQueue-JNI(996):    at android.view.ViewRootImpl.deliverPointerEvent(ViewRootImpl.java:3220)
02-14 14:38:09.207: E/MessageQueue-JNI(996):    at android.view.ViewRootImpl.deliverInputEvent(ViewRootImpl.java:3165)
02-14 14:38:09.207: E/MessageQueue-JNI(996):    at android.view.ViewRootImpl.doProcessInputEvents(ViewRootImpl.java:4292)
02-14 14:38:09.207: E/MessageQueue-JNI(996):    at android.view.ViewRootImpl.enqueueInputEvent(ViewRootImpl.java:4271)
02-14 14:38:09.207: E/MessageQueue-JNI(996):    at android.view.ViewRootImpl$WindowInputEventReceiver.onInputEvent(ViewRootImpl.java:4363)
02-14 14:38:09.207: E/MessageQueue-JNI(996):    at android.view.InputEventReceiver.dispatchInputEvent(InputEventReceiver.java:179)
02-14 14:38:09.207: E/MessageQueue-JNI(996):    at android.os.MessageQueue.nativePollOnce(Native Method)
02-14 14:38:09.207: E/MessageQueue-JNI(996):    at android.os.MessageQueue.next(MessageQueue.java:125)
02-14 14:38:09.207: E/MessageQueue-JNI(996):    at android.os.Looper.loop(Looper.java:124)
02-14 14:38:09.207: E/MessageQueue-JNI(996):    at android.app.ActivityThread.main(ActivityThread.java:5039)
02-14 14:38:09.207: E/MessageQueue-JNI(996):    at java.lang.reflect.Method.invokeNative(Native Method)
02-14 14:38:09.207: E/MessageQueue-JNI(996):    at java.lang.reflect.Method.invoke(Method.java:511)
02-14 14:38:09.207: E/MessageQueue-JNI(996):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
02-14 14:38:09.207: E/MessageQueue-JNI(996):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
02-14 14:38:09.207: E/MessageQueue-JNI(996):    at dalvik.system.NativeStart.main(Native Method)
02-14 14:38:09.247: D/AndroidRuntime(996): Shutting down VM
02-14 14:38:09.247: W/dalvikvm(996): threadid=1: thread exiting with uncaught exception (group=0x40a70930)
02-14 14:38:09.327: E/AndroidRuntime(996): FATAL EXCEPTION: main
02-14 14:38:09.327: E/AndroidRuntime(996): java.lang.NullPointerException
02-14 14:38:09.327: E/AndroidRuntime(996):  at com.carouseldemo.main.MainActivity$1.onItemClick(MainActivity.java:50)
02-14 14:38:09.327: E/AndroidRuntime(996):  at com.carouseldemo.controls.CarouselAdapter.performItemClick(CarouselAdapter.java:261)
02-14 14:38:09.327: E/AndroidRuntime(996):  at com.carouseldemo.controls.Carousel.onSingleTapUp(Carousel.java:967)
02-14 14:38:09.327: E/AndroidRuntime(996):  at android.view.GestureDetector.onTouchEvent(GestureDetector.java:588)
02-14 14:38:09.327: E/AndroidRuntime(996):  at com.carouseldemo.controls.Carousel.onTouchEvent(Carousel.java:311)
02-14 14:38:09.327: E/AndroidRuntime(996):  at android.view.View.dispatchTouchEvent(View.java:7239)
02-14 14:38:09.327: E/AndroidRuntime(996):  at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2168)
02-14 14:38:09.327: E/AndroidRuntime(996):  at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1903)
02-14 14:38:09.327: E/AndroidRuntime(996):  at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2174)
02-14 14:38:09.327: E/AndroidRuntime(996):  at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1917)
02-14 14:38:09.327: E/AndroidRuntime(996):  at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2174)
02-14 14:38:09.327: E/AndroidRuntime(996):  at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1917)
02-14 14:38:09.327: E/AndroidRuntime(996):  at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2174)
02-14 14:38:09.327: E/AndroidRuntime(996):  at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1917)
02-14 14:38:09.327: E/AndroidRuntime(996):  at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2174)
02-14 14:38:09.327: E/AndroidRuntime(996):  at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1917)
02-14 14:38:09.327: E/AndroidRuntime(996):  at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2174)
02-14 14:38:09.327: E/AndroidRuntime(996):  at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1917)
02-14 14:38:09.327: E/AndroidRuntime(996):  at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:1953)
02-14 14:38:09.327: E/AndroidRuntime(996):  at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1405)
02-14 14:38:09.327: E/AndroidRuntime(996):  at android.app.Activity.dispatchTouchEvent(Activity.java:2410)
02-14 14:38:09.327: E/AndroidRuntime(996):  at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:1901)
02-14 14:38:09.327: E/AndroidRuntime(996):  at android.view.View.dispatchPointerEvent(View.java:7419)
02-14 14:38:09.327: E/AndroidRuntime(996):  at android.view.ViewRootImpl.deliverPointerEvent(ViewRootImpl.java:3220)
02-14 14:38:09.327: E/AndroidRuntime(996):  at android.view.ViewRootImpl.deliverInputEvent(ViewRootImpl.java:3165)
02-14 14:38:09.327: E/AndroidRuntime(996):  at android.view.ViewRootImpl.doProcessInputEvents(ViewRootImpl.java:4292)
02-14 14:38:09.327: E/AndroidRuntime(996):  at android.view.ViewRootImpl.enqueueInputEvent(ViewRootImpl.java:4271)
02-14 14:38:09.327: E/AndroidRuntime(996):  at android.view.ViewRootImpl$WindowInputEventReceiver.onInputEvent(ViewRootImpl.java:4363)
02-14 14:38:09.327: E/AndroidRuntime(996):  at android.view.InputEventReceiver.dispatchInputEvent(InputEventReceiver.java:179)
02-14 14:38:09.327: E/AndroidRuntime(996):  at android.os.MessageQueue.nativePollOnce(Native Method)
02-14 14:38:09.327: E/AndroidRuntime(996):  at android.os.MessageQueue.next(MessageQueue.java:125)
02-14 14:38:09.327: E/AndroidRuntime(996):  at android.os.Looper.loop(Looper.java:124)
02-14 14:38:09.327: E/AndroidRuntime(996):  at android.app.ActivityThread.main(ActivityThread.java:5039)
02-14 14:38:09.327: E/AndroidRuntime(996):  at java.lang.reflect.Method.invokeNative(Native Method)
02-14 14:38:09.327: E/AndroidRuntime(996):  at java.lang.reflect.Method.invoke(Method.java:511)
02-14 14:38:09.327: E/AndroidRuntime(996):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
02-14 14:38:09.327: E/AndroidRuntime(996):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
02-14 14:38:09.327: E/AndroidRuntime(996):  at dalvik.system.NativeStart.main(Native Method)
4

2 に答える 2

0

parent.getChildAt(i) は、i 番目の項目を表す子ビューではなく、親の i 番目の VISIBLE 子ビューを提供します。

別の言い方で説明しましょう。AdapterView に 100 個の項目があるとします。あなたは、parent.getChildAt(99) が最後の項目を表すビューを与えると期待するかもしれません: これは間違っています。パフォーマンスの問題のために、AdapterView は現在表示する必要があるアイテムの子ビューを作成します。たとえば、リストの一番上までスクロールし、5 つの項目が表示されている場合、AdapterView にはおそらく 5 つまたは 6 つの子ビューがあります。この場合、parent.getChildAt(99) は null 参照を返します。

実際には、クリックされた子ビューは、onItemClicked メソッド (2 番目の「view」引数) を介して既に指定されています。次のようにコードを変更できます。

Toast.makeText(MainActivity.this, 
    String.format("%s has been clicked",    
    ((CarouselItem)view).getName()), 
    Toast.LENGTH_SHORT).show();

編集:

さらに、次のコード フラグメントも疑わしいものです。

        LayoutInflater inflater = getLayoutInflater();
        View layout = inflater.inflate(R.layout.toast_layout,
                                       (ViewGroup) findViewById(R.id.toast_layout_root));


        TextView text = (TextView) layout.findViewById(R.id.selected_item);
        text.setText("This is a custom toast");

ここでは、toast_layout.xml をビューにインフレートし、アプリケーション ウィンドウに既にアタッチされている別のビュー (R.id.toast_layout_root) に追加します。これにより、toast_layout.xml から膨張したビューがメイン アプリケーション ウィンドウに表示されます。

ただし、別のウィンドウとしてレンダリングされるトーストのレイアウトとして、膨張したビューを使用します。

于 2013-02-14T15:17:57.447 に答える