安卓学习-界面-ui-NumberPicker

<RelativeLayout 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"
    tools:context="${relativePackage}.${activityClass}" >

    <NumberPicker
        android:id="@+id/numberPicker1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true" />

    <TextView
        android:id="@+id/textView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_below="@+id/numberPicker1"
        android:layout_marginLeft="17dp"
        android:text="数值："
        android:textAppearance="?android:attr/textAppearanceLarge" />

    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_marginTop="18dp"
        android:layout_toRightOf="@+id/textView1"
        android:text="设置成50" />

</RelativeLayout>

public class MainActivity extends Activity {

    NumberPicker numberPicker;
    Button button1;
    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        numberPicker=(NumberPicker)findViewById(R.id.numberPicker1);
        numberPicker.setMaxValue(100);
        numberPicker.setMinValue(1);
        numberPicker.setOnValueChangedListener(new OnValueChangeListener() {
            
            @Override
            public void onValueChange(NumberPicker picker, int oldVal, int newVal) {
                TextView textView1=(TextView)findViewById(R.id.textView1);
                textView1.setText("原【"+oldVal+"】"+"改成【"+newVal+"】");
            }
        });

        
        button1=(Button)findViewById(R.id.button1);
        button1.setOnClickListener(new OnClickListener() {
            public void onClick(View v) {
                //这里居然不会触发setOnValueChangedListener，算是bug吗
                numberPicker.setValue(50);
                
            }
        });
    }
}