Question

我正在尝试为我的Sony Smartwatch 3编写应用程序，并且对初步掌握Android编程知识。我在我的应用程序中添加了一个按钮，我正在尝试连接所述按钮。唯一的问题是当我添加setOnClickListener时，我的应用程序崩溃并且无法加载。当我删除两个箭头之间指示的代码时，应用程序启动，按钮显示，我可以单击它（当然没有任何反应）。所以我不确定我做错了什么，我已经搜索过并且没有找到任何答案。任何帮助都是非常有必要的，安装android的提示和技巧会非常棒！

super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_wear_start);
    final WatchViewStub stub = (WatchViewStub) findViewById(R.id.watch_view_stub);
    stub.setOnLayoutInflatedListener(new WatchViewStub.OnLayoutInflatedListener()
    {
        @Override
        public void onLayoutInflated(WatchViewStub stub)
        {
            mTextView = (TextView) stub.findViewById(R.id.text);
        }
    });
    Button startingButton = (Button) findViewById(R.id.starting_button);
--> startingButton.setOnClickListener(new View.OnClickListener()
    {

        @Override
        public void onClick(View v)
        {
            Toast.makeText(WearStart.this, "You clicked it!", Toast.LENGTH_LONG).show();
        }
--> });

activity_wear_start.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.wearable.view.WatchViewStub
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools" android:id="@+id/watch_view_stub"
android:layout_width="match_parent" android:layout_height="match_parent"
app:rectLayout="@layout/rect_activity_wear_start"
app:roundLayout="@layout/round_activity_wear_start" tools:context=".WearStart"
tools:deviceIds="wear"></android.support.wearable.view.WatchViewStub>

rect_activity_wear_start.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
android:layout_height="match_parent" android:orientation="vertical" tools:context=".WearStart"
tools:deviceIds="wear_square">

<Button
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:text="@string/start_button"
    android:id="@+id/starting_button"
    android:layout_gravity="center_horizontal"
    android:clickable="true"
    android:enabled="true" />
</LinearLayout>

崩溃日志

01-01 22:35:50.587    8740-8740/petryszak.kyle.dash E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: petryszak.kyle.dash, PID: 8740
java.lang.RuntimeException: Unable to start activity ComponentInfo{petryszak.kyle.dash/petryszak.kyle.dash.WearStart}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2298)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
        at android.app.ActivityThread.access$800(ActivityThread.java:144)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
        at android.os.Handler.dispatchMessage(Handler.java:102)
        at android.os.Looper.loop(Looper.java:135)
        at android.app.ActivityThread.main(ActivityThread.java:5221)
        at java.lang.reflect.Method.invoke(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:372)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
 Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
        at petryszak.kyle.dash.WearStart.onCreate(WearStart.java:34)
        at android.app.Activity.performCreate(Activity.java:5943)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2251)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
            at android.app.ActivityThread.access$800(ActivityThread.java:144)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5221)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)

Answer 1

将button's click event放在onLayoutInflated()方法中作为

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_home);
    final WatchViewStub stub = (WatchViewStub) findViewById(R.id.watch_view_stub);
    stub.setOnLayoutInflatedListener(new WatchViewStub.OnLayoutInflatedListener() {
        @Override
        public void onLayoutInflated(WatchViewStub stub) {
            mTextView = (TextView) stub.findViewById(R.id.text);
            imageButton=(ImageButton)stub.findViewById(R.id.imageButton);

            imageButton.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                    //Toast.makeText(getApplicationContext(),"Haiii",Toast.LENGTH_LONG).show();

                    Intent toNext=new Intent(Home.this,SecondActivity.class);
                    startActivity(toNext);

                }
            });


        }
    });
}

并完成此link。这对于Android可穿戴应用程序开发非常有用。

Android Wear setOnClickListener崩溃

1 个答案: