Android跑马灯失效原因

以下两种方法都可以

1.在activity_text_view.xml中的标签外面添加

2.给activity_text_view.xml中的标签取个id，然后在TextViewActivity.java中添加

TextView textView1 = findViewById(R.id.tv_1);
textView1.setSelected(true);

完整代码如下：
　　activity_text_view.xml文件

    android:id="@+id/tv_1"
    android:padding="10dp"
    android:background="#ff00ff00"
    android:layout_centerInParent="true"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:singleLine="true"
    android:ellipsize="marquee"
    android:focusable="true"
    android:focusableInTouchMode="true"
    android:marqueeRepeatLimit="marquee_forever"
    android:text="Always believe that something wonderful is about to happen" />

　　TextViewActivity.java文件

public class TextViewActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_text_view2);
        TextView textView1 = findViewById(R.id.tv_1);
        textView1.setSelected(true);
    }
}