Android 布局中的点击监听器

Question

您好，这是我的自定义视图，当我设置点击侦听器时出现空指针异常。

public class PestButtons extends AbsoluteLayout{

    private LayoutInflater inflater;

    private OnClickListener screenshotOnClickListener = new OnClickListener() {
        public void onClick(View v) {
      //      getContext().startActivity(new Intent(getContext(), ScreenshotActivity.class));
        Log.i("a", "a");
        }
    };  


    public PestButtons(Context context, AttributeSet attrs) {
        super(context, attrs);

        inflater = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        inflater.inflate(R.layout.pestbuttons, this,true);
         ImageButton img = (ImageButton) this.findViewById(R.id.reportListBtn);
              img.setOnClickListener(screenshotOnClickListener);

    }




}

xml：

<?xml version="1.0" encoding="UTF-8"?>



<merge xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent">


    <ImageButton id="@+id/reportListBtn"
    android:src="@drawable/reportlist"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
   android:layout_x="5px"
    android:layout_y="20px"

/>



 </merge>

我的使用布局：

<?xml version="1.0" encoding="utf-8"?>
<AbsoluteLayout
    android:id="@+id/main"

android:layout_width="fill_parent"
android:layout_height="fill_parent"
xmlns:android="http://schemas.android.com/apk/res/android"
>

<com.AgricultureTrading.PestButtons
            android:layout_width="fill_parent"
            android:layout_height="fill_parent" />

<TextView
android:id="@+id/err"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textColor="#ffff0000"
android:layout_x="320px"
android:layout_y="25px"

/>

<TextView
android:id="@+id/weather"
android:layout_width="260px"
android:layout_height="wrap_content"
android:layout_x="140px"
android:layout_y="60px"
/>

<ImageView
android:id="@+id/loaderImageView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_x="395px"
android:layout_y="60px"
/>

<Button
android:id="@+id/playBtn"
android:layout_width="93px"
android:layout_height="wrap_content"
android:text="Play sound"
android:layout_x="140px"
android:layout_y="120px"
android:onClick="playBtn_click"
/>


<ImageButton
android:id="@+id/userimage"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_x="150px"
android:layout_y="5px"
android:onClick="changeimage_click"
/>

<TextView
android:id="@+id/weatherLbl"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="TextView"
android:layout_x="140px"
android:layout_y="96px"
/>      
</AbsoluteLayout>

错误日志：

09:51:56.153 717 com.AgricultureTrading ERROR AndroidRuntime FATAL EXCEPTION: main 09:51:56.153 717 com.AgricultureTrading 错误 AndroidRuntime java.lang.RuntimeException：无法启动活动 ComponentInfo{com.AgricultureTrading/com.AgricultureTrading.Tabs}：java.lang.RuntimeException：无法启动活动 ComponentInfo{com.AgricultureTrading/ com.AgricultureTrading.ProfileActivity}：android.view.InflateException：二进制 XML 文件第 68 行：膨胀类 com.AgricultureTrading.PestButtons 时出错 09:51:56.153 717 com.AgricultureTrading 错误 AndroidRuntime 在 android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1815) 09:51:56.153 717 com.AgricultureTrading 错误 AndroidRuntime 在 android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1831) 09:51:56.153 717 com.AgricultureTrading ERROR AndroidRuntime at android.app.ActivityThread.access$500(ActivityThread.java:122) 09:51:56.153 717 com.AgricultureTrading 错误 AndroidRuntime 在 android.app.ActivityThread$H.handleMessage(ActivityThread.java:1024) 09:51:56.153 717 com.AgricultureTrading 错误 AndroidRuntime 在 android.os.Handler.dispatchMessage(Handler.java:99) 09:51:56.153 717 com.AgricultureTrading 错误 AndroidRuntime at android.os.Looper.loop(Looper.java:132) 09:51:56.153 717 com.AgricultureTrading 错误 AndroidRuntime at android.app.ActivityThread.main(ActivityThread.java:4123) 09:51:56.153 717 com.AgricultureTrading ERROR AndroidRuntime at java.lang.reflect.Method.invokeNative(Native Method) 09:51:56.153 717 com.AgricultureTrading 错误 AndroidRuntime 在 java.lang.reflect.Method.invoke(Method.java:491) 09:51:56.153 717 com.AgricultureTrading 错误 AndroidRuntime at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:841) 09:51:56.153 717 com.AgricultureTrading 错误 AndroidRuntime at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:599) 09:51:56.153 717 com.AgricultureTrading ERROR AndroidRuntime at dalvik.system.NativeStart.main(Native Method) 09:51:56.153 717 com.AgricultureTrading 错误 AndroidRuntime 原因：java.lang.RuntimeException：无法启动活动 ComponentInfo{com.AgricultureTrading/com.AgricultureTrading.ProfileActivity}：android.view.InflateException：二进制 XML 文件第 68 行：膨胀类 com.AgricultureTrading.PestButtons 时出错 09:51:56.153 717 com.AgricultureTrading 错误 AndroidRuntime at android.app.ActivityThread.startActivityNow(ActivityThread.java:1656) 09:51:56.153 717 com.AgricultureTrading 错误 AndroidRuntime 在 android.app.LocalActivityManager.moveToState(LocalActivityManager.java:135) 09:51:56.153 717 com.AgricultureTrading 错误 AndroidRuntime 在 android.app.LocalActivityManager.startActivity(LocalActivityManager.java:347) 09:51:56.153 717 com.AgricultureTrading 错误 AndroidRuntime 在 android.widget.TabHost$IntentContentStrategy.getContentView(TabHost.java:676) 09:51:56.153 717 com.AgricultureTrading 错误 AndroidRuntime 在 android.widget.TabHost.setCurrentTab(TabHost.java:345) 09:51:56.153 717 com.AgricultureTrading 错误 AndroidRuntime at com.AgricultureTrading.Tabs.onCreate(Tabs.java:34) 09:51:56.153 717 com.AgricultureTrading 错误 AndroidRuntime at android.app.Activity.performCreate(Activity.java:4397) 09:51:56.153 717 com.AgricultureTrading 错误 AndroidRuntime 在 android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1048) 09:51:56.153 717 com.AgricultureTrading 错误 AndroidRuntime 在 android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1779) 09:51:56.153 717 com.AgricultureTrading ERROR AndroidRuntime ... 11 更多 09:51:56.153 717 com.AgricultureTrading 错误 AndroidRuntime 原因：android.view.InflateException：二进制 XML 文件行 #68：膨胀类 com.AgricultureTrading.PestButtons 时出错 09:51:56.153 717 com.AgricultureTrading 错误 AndroidRuntime at android.view.LayoutInflater.createView(LayoutInflater.java:596) 09:51:56.153 717 com.AgricultureTrading 错误 AndroidRuntime 在 android.view.LayoutInflater.createViewFromTag（LayoutInflater.java:671） 09:51:56.153 717 com.AgricultureTrading 错误 AndroidRuntime 在 android.view.LayoutInflater.rInflate(LayoutInflater.java:724) 09:51:56.153 717 com.AgricultureTrading 错误 AndroidRuntime at android.view.LayoutInflater.inflate(LayoutInflater.java:479) 09:51:56.153 717 com.AgricultureTrading 错误 AndroidRuntime at android.view.LayoutInflater.inflate(LayoutInflater.java:391) 09:51:56.153 717 com.AgricultureTrading 错误 AndroidRuntime at android.view.LayoutInflater.inflate(LayoutInflater.java:347) 09:51:56.153 717 com.AgricultureTrading 错误 AndroidRuntime 在 com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:223) 09:51:56.153 717 com.AgricultureTrading 错误 AndroidRuntime at android.app.Activity.setContentView(Activity.java:1786) 09:51:56.153 717 com.AgricultureTrading 错误 AndroidRuntime at com.AgricultureTrading.ProfileActivity.onCreate(ProfileActivity.java:43) 09:51:56.153 717 com.AgricultureTrading ERROR AndroidRuntime ... 20 更多 09:51:56.153 717 com.AgricultureTrading 错误 AndroidRuntime 原因：java.lang.reflect.InvocationTargetException 09:51:56.153 717 com.AgricultureTrading ERROR AndroidRuntime at java.lang.reflect.Constructor.constructNative(Native Method) 09:51:56.153 717 com.AgricultureTrading 错误 AndroidRuntime 在 java.lang.reflect.Constructor.newInstance（Constructor.java:416） 09:51:56.153 717 com.AgricultureTrading 错误 AndroidRuntime at android.view.LayoutInflater.createView(LayoutInflater.java:576) 09:51:56.153 717 com.AgricultureTrading ERROR AndroidRuntime ... 31 更多 09:51:56.153 717 com.AgricultureTrading ERROR AndroidRuntime 引起：java.lang.NullPointerException 09:51:56.153 717 com.AgricultureTrading 错误 AndroidRuntime at com.AgricultureTrading.PestButtons.(PestButtons.java:43) 09:51:56.153 717 com.AgricultureTrading ERROR AndroidRuntime ... 34 更多

Answer 1

我假设您想从膨胀视图中获取 img：

         View v = inflater.inflate(R.layout.pestbuttons, this,true);
         ImageButton img = (ImageButton) v.findViewById(R.id.reportListBtn);
         if (img != null) {
             img.setOnClickListener(screenshotOnClickListener);
         }