带有自实现的OnClickListener的NullPointerException

Question

抱歉，但是好像到处都是，过去几天各种OnClickListener东西都无法使用...

我有一个显示的固定的各种变量/数据（联系人）的ListView，对于每个ListView项，我正在使用一个单独的XML文件（ contacts_item ）来格式化/显示此数据。 ListView中的每个项目都是电话联系人或电子邮件联系人。 我正在努力做到这一点，以便在单击其中一个联系人时，它将开始拨打电话或显示新电子邮件。 （现在仅关注呼叫方面，那有什么关系？）

来自主要活动的代码片段：

public void onCreate(Bundle saveInstanceState) {
    super.onCreate(saveInstanceState);
    setContentView(R.layout.contacts_layout);

    // Show "back" button
    aboutButton = (Button) findViewById(R.id.aboutButton);
    aboutButton.setOnClickListener(new OnClickListener() {
        public void onClick(View v) {
            Contacts.this.finish();
        }
    });

ListView listview = (ListView) findViewById(R.id.contactItem);
ArrayList<HashMap<String, String>> items = new ArrayList<HashMap<String, String>>();
// loop through 8 times for each contact entry
for (int i = 0; i < 8; i++) {
        HashMap<String, String> entry = new HashMap<String, String>();
        entry.put("title", title[i]);
        entry.put("name", name[i]);
        entry.put("label", label[i]); // Call, mail, etc.
        entry.put("info", info[i]); // The actual phone number or email

        // Check the label field of each entry
        if (label[i].equals("Call")) {
            TextLabel = (TextView) findViewById(R.id.contactLabel); // contactLabel is from the separate XML file I mentioned
            Log.v("textlabel", "textlabel: " + R.id.contactLabel);

            // Crashes here              
            //TextLabel.setOnClickListener(new ContactOCL(info[i]));
        }

        // Let's see if all of this is printing out right
        Log.v("title", "Title: " + title[i]);
        Log.v("name", "Name: " + name[i]);
        Log.v("label", "Label: " + label[i]);
        Log.v("info", "Info: " + info[i]);

        items.add(entry);
}

ListAdapter adapter = new SimpleAdapter(Contacts.this, items, R.layout.contacts_item, new String[] {"title", "name", "label", "info"},
            new int[] {R.id.contactTitle, R.id.contactName, R.id.contactLabel, R.id.contactInfo});

    // Create an inflater to use another xml layout (the Facebook/Twitter/Instagram buttons)
    LayoutInflater inflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    View footerView = inflater.inflate(R.layout.contacts_footer, null);

    // Define their clicks
    facebookButton = (ImageButton) footerView.findViewById(R.id.facebookButton);
    twitterButton = (ImageButton) footerView.findViewById(R.id.twitterButton);
    instagramButton = (ImageButton) footerView.findViewById(R.id.instagramButton);

    facebookButton.setOnClickListener(new OnClickListener() {
        public void onClick(View v) {
            // Open up the Facebook page when clicked
            facebookPage = new Intent(android.content.Intent.ACTION_VIEW);
            facebookPage.setData(Uri.parse(facebookURL));
            startActivity(facebookPage);
        }
    });

    twitterButton.setOnClickListener(new OnClickListener() {
        public void onClick(View v) {
            // Open up the Twitter page when clicked
            twitterPage = new Intent(android.content.Intent.ACTION_VIEW);
            twitterPage.setData(Uri.parse(twitterURL));
            startActivity(twitterPage);
        }
    });

    instagramButton.setOnClickListener(new OnClickListener() {
        public void onClick(View v) {
            // Open up the Instagram page when clicked
            instagramPage = new Intent(android.content.Intent.ACTION_VIEW);
            instagramPage.setData(Uri.parse(instagramURL));
            startActivity(instagramPage);
        }
    });

    // Add the footer to the listview, then set adapter
    // MUST BE CALLED IN THIS ORDER!
    listview.addFooterView(footerView);
    listview.setAdapter(adapter);

联系方式：

public class ContactOCL extends Activity implements OnClickListener {
    String contactInfo;
    public ContactOCL(String contactInfo) {
        this.contactInfo = contactInfo;
    }

    public void onClick(View v) {
        try {
            Intent callIntent = new Intent(Intent.ACTION_CALL);
            callIntent.setData(Uri.parse("tel:" + contactInfo));
            v.getContext().startActivity(callIntent);
        } catch (ActivityNotFoundException activityException) {
            Log.e("Calling a Phone Number", "Call failed", activityException);
        }
    }

}

这是堆栈跟踪：

02-27 16:29:15.813: E/AndroidRuntime(1025): FATAL EXCEPTION: main
02-27 16:29:15.813: E/AndroidRuntime(1025): java.lang.RuntimeException: Unable to start activity ComponentInfo{org.radio.app/org.radio.app.Contacts}: java.lang.NullPointerException
02-27 16:29:15.813: E/AndroidRuntime(1025):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2059)
02-27 16:29:15.813: E/AndroidRuntime(1025):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
02-27 16:29:15.813: E/AndroidRuntime(1025):     at android.app.ActivityThread.access$600(ActivityThread.java:130)
02-27 16:29:15.813: E/AndroidRuntime(1025):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
02-27 16:29:15.813: E/AndroidRuntime(1025):     at android.os.Handler.dispatchMessage(Handler.java:99)
02-27 16:29:15.813: E/AndroidRuntime(1025):     at android.os.Looper.loop(Looper.java:137)
02-27 16:29:15.813: E/AndroidRuntime(1025):     at android.app.ActivityThread.main(ActivityThread.java:4745)
02-27 16:29:15.813: E/AndroidRuntime(1025):     at java.lang.reflect.Method.invokeNative(Native Method)
02-27 16:29:15.813: E/AndroidRuntime(1025):     at java.lang.reflect.Method.invoke(Method.java:511)
02-27 16:29:15.813: E/AndroidRuntime(1025):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
02-27 16:29:15.813: E/AndroidRuntime(1025):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
02-27 16:29:15.813: E/AndroidRuntime(1025):     at dalvik.system.NativeStart.main(Native Method)
02-27 16:29:15.813: E/AndroidRuntime(1025): Caused by: java.lang.NullPointerException
02-27 16:29:15.813: E/AndroidRuntime(1025):     at org.radio.app.Contacts.onCreate(Contacts.java:78)
02-27 16:29:15.813: E/AndroidRuntime(1025):     at android.app.Activity.performCreate(Activity.java:5008)
02-27 16:29:15.813: E/AndroidRuntime(1025):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079)
02-27 16:29:15.813: E/AndroidRuntime(1025):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2023)

textlabel也打印了几次，所有的都是相同的数字/ ID ...我假设这是一个不好的信号，而不是我想要的。 所以我不太确定是不是我的实现导致了崩溃，还是...

Answer 1

你不能用一个View ，如TextView或Button从Layout尚未使用充气setContentView()或layoutInflater 。 除非我想念您这样做的地方，否则这似乎是您的问题。 将Views放在要使用的Layout ，然后可以按需要更改属性，以便进一步格式化