android - FindViewById 不适用于按钮

Question

我有一个代码，以前可以用，现在不行了。

    public void SetVisibilitySuggestions(int vis)
        //4: INVISIBLE, 0: VISIBLE
        {
            Button b1 = (Button) findViewById(R.id.background1);
            b1.setVisibility(vis);
            Button b2 = (Button) findViewById(R.id.background2);
            b2.setVisibility(vis);
            Button b3 = (Button) findViewById(R.id.background3);
            b3.setVisibility(vis);
            Button b4 = (Button) findViewById(R.id.background4);
            b4.setVisibility(vis);
            t1.setVisibility(vis);
            t2.setVisibility(vis);
            t3.setVisibility(vis);
            t4.setVisibility(vis);
        }

        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            this.requestWindowFeature(Window.FEATURE_NO_TITLE);
            setContentView(R.layout.activity_main);

            t1 = (TextView) findViewById(R.id.textView1);
            t2 = (TextView) findViewById(R.id.textView2);
            t3 = (TextView) findViewById(R.id.textView3);
            t4 = (TextView) findViewById(R.id.textView4);

            t = (EditText) findViewById(R.id.editText);
            t.setTypeface(Typeface.createFromAsset(getBaseContext().getAssets(), "fonts/UniversLTStd-Cn.otf"));

            SetVisibilitySuggestions(4);    //4: INVISIBLE, 0: VISIBLE
.
.
.

SetVisibilitySuggestions 函数中的第一个 FindViewById 不起作用。可能是什么问题呢？有人提议清理 R 文件。他说有时他们会变得困惑。对于初学者，您是怎么做到的？

编辑:LogCat

06-06 21:40:04.790: E/AndroidRuntime(2840): FATAL EXCEPTION: main
06-06 21:40:04.790: E/AndroidRuntime(2840): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.googlesearch/com.example.googlesearch.MainActivity}: java.lang.ClassCastException: android.widget.TextView cannot be cast to android.widget.Button
06-06 21:40:04.790: E/AndroidRuntime(2840):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
06-06 21:40:04.790: E/AndroidRuntime(2840):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
06-06 21:40:04.790: E/AndroidRuntime(2840):     at android.app.ActivityThread.access$600(ActivityThread.java:141)
06-06 21:40:04.790: E/AndroidRuntime(2840):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
06-06 21:40:04.790: E/AndroidRuntime(2840):     at android.os.Handler.dispatchMessage(Handler.java:99)
06-06 21:40:04.790: E/AndroidRuntime(2840):     at android.os.Looper.loop(Looper.java:137)
06-06 21:40:04.790: E/AndroidRuntime(2840):     at android.app.ActivityThread.main(ActivityThread.java:5039)
06-06 21:40:04.790: E/AndroidRuntime(2840):     at java.lang.reflect.Method.invokeNative(Native Method)
06-06 21:40:04.790: E/AndroidRuntime(2840):     at java.lang.reflect.Method.invoke(Method.java:511)
06-06 21:40:04.790: E/AndroidRuntime(2840):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
06-06 21:40:04.790: E/AndroidRuntime(2840):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
06-06 21:40:04.790: E/AndroidRuntime(2840):     at dalvik.system.NativeStart.main(Native Method)
06-06 21:40:04.790: E/AndroidRuntime(2840): Caused by: java.lang.ClassCastException: android.widget.TextView cannot be cast to android.widget.Button
06-06 21:40:04.790: E/AndroidRuntime(2840):     at com.example.googlesearch.MainActivity.onCreate(MainActivity.java:151)
06-06 21:40:04.790: E/AndroidRuntime(2840):     at android.app.Activity.performCreate(Activity.java:5104)
06-06 21:40:04.790: E/AndroidRuntime(2840):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
06-06 21:40:04.790: E/AndroidRuntime(2840):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
06-06 21:40:04.790: E/AndroidRuntime(2840):     ... 11 more

XML 文件:

<Button
        android:id="@+id/background1"
        android:layout_width="258px"
        android:layout_height="45px"
        android:layout_alignBaseline="@+id/textView1"
        android:layout_alignLeft="@+id/editText"
        android:background="@drawable/sugg_back"
        android:clickable="false" />

    <Button
        android:id="@+id/background2"
        android:layout_width="258px"
        android:layout_height="45px"
        android:layout_alignBaseline="@+id/textView2"
        android:layout_alignLeft="@+id/editText"
        android:background="@drawable/sugg_back"
        android:clickable="false" />

    <Button
        android:id="@+id/background3"
        android:layout_width="258px"
        android:layout_height="45px"
        android:layout_alignBaseline="@+id/textView3"
        android:layout_alignLeft="@+id/editText"
        android:background="@drawable/sugg_back"
        android:clickable="false" />

    <Button
        android:id="@+id/background4"
        android:layout_width="258px"
        android:layout_height="45px"
        android:layout_alignBaseline="@+id/textView4"
        android:layout_alignLeft="@+id/editText"
        android:background="@drawable/sugg_back"
        android:clickable="false" />

Answer 1

如日志中所示:

java.lang.ClassCastException: android.widget.TextView cannot be cast to android.widget.Button

表示您正在尝试将 TextView 转换为当前代码中的 Button。因此，只要确保您使用正确的 ID 来初始化 View ，并且如果您正在使用，还可以从 Project->Clean 菜单选项中清理项目Eclipse 集成开发环境