<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);                            }        });    }}