我想使用一个微调器，最初(当用户还没有做出选择时)显示文本“Select One”。当用户单击微调器时，将显示项目列表，用户可以选择其中一个选项。用户做出选择后，所选项目将显示在微调器中，而不是“Select One”。
我有以下代码来创建一个旋转器:
String[] items = new String[] {"One", "Two", "Three"};
Spinner spinner = (Spinner) findViewById(R.id.mySpinner);
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,
android.R.layout.simple_spinner_item, items);
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinner.setAdapter(adapter);
使用这段代码，最初会显示项目“One”。我可以在项目中添加一个新项目“Select One”，但“Select One”也会作为第一项显示在下拉列表中，这不是我想要的。
我该如何解决这个问题?
private boolean isFirst = true;
private void setAdapter() {
final ArrayList<String> spinnerArray = new ArrayList<String>();
spinnerArray.add("Select your option");
spinnerArray.add("Option 1");
spinnerArray.add("Option 2");
spin.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
@Override
public void onItemSelected(AdapterView<?> parentView, View selectedItemView, int position, long id) {
TextView tv = (TextView)selectedItemView;
String res = tv.getText().toString().trim();
if (res.equals("Option 1")) {
//do Something
} else if (res.equals("Option 2")) {
//do Something else
}
}
@Override
public void onNothingSelected(AdapterView<?> parentView) { }
});
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, R.layout.my_spinner_style,spinnerArray) {
public View getView(int position, View convertView, ViewGroup parent) {
View v = super.getView(position, convertView, parent);
int height = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 25, getResources().getDisplayMetrics());
((TextView) v).setTypeface(tf2);
((TextView) v).getLayoutParams().height = height;
((TextView) v).setGravity(Gravity.CENTER);
((TextView) v).setTextSize(TypedValue.COMPLEX_UNIT_SP, 19);
((TextView) v).setTextColor(Color.WHITE);
return v;
}
public View getDropDownView(int position, View convertView,
ViewGroup parent) {
if (isFirst) {
isFirst = false;
spinnerArray.remove(0);
}
View v = super.getDropDownView(position, convertView, parent);
((TextView) v).setTextColor(Color.argb(255, 70, 70, 70));
((TextView) v).setTypeface(tf2);
((TextView) v).setGravity(Gravity.CENTER);
return v;
}
};
spin.setAdapter(adapter);
}
没有默认的API来设置微调提示。为了添加它，我们需要一个小的解决方案，而不是安全反射实现
List<Object> objects = new ArrayList<Object>();
objects.add(firstItem);
objects.add(secondItem);
// add hint as last item
objects.add(hint);
HintAdapter adapter = new HintAdapter(context, objects, android.R.layout.simple_spinner_item);
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
Spinner spinnerFilmType = (Spinner) findViewById(R.id.spinner);
spinner.setAdapter(adapter);
// show hint
spinner.setSelection(adapter.getCount());
适配器来源:
public class HintAdapter
extends ArrayAdapter<Objects> {
public HintAdapter(Context theContext, List<Object> objects) {
super(theContext, android.R.id.text1, android.R.id.text1, objects);
}
public HintAdapter(Context theContext, List<Object> objects, int theLayoutResId) {
super(theContext, theLayoutResId, android.R.id.text1, objects);
}
@Override
public int getCount() {
// don't display last item. It is used as hint.
int count = super.getCount();
return count > 0 ? count - 1 : count;
}
}
原始来源
考虑有N个项目要选择。
添加完这N个项目后，添加提示文本作为(N+1)个项目。
将所选项目设置为第N个位置[(N+1)个项目]。
在OnItemSelected Listener中，如果所选位置不是N，弹出最后一个项目并调用Adapter.notifyDataSetChanged()并将所选项目设置为所选位置。
就像这样:
spinner.setItems("Daily", "One time", "Frequency"); // here "Frequency is the hint text"
spinner.setSelectedIndex(2);
spinner.setOnItemSelectedListener(new OnItemSelectedListener() {
@Override
public void onItemSelected(Spinner view, int position, long id, Object item) {
if (position != 2) {
view.setItems("Daily", "One time");
view.setSelectedIndex(position);
}else {
// This item is not a valid selection
}
}
});
这是我最后一个“all in”按钮旋转器的例子
在activity_my_form.xml
<Button
android:id="@+id/btnSpinnerPlanets"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:gravity="left|center_vertical"
android:singleLine="true"
android:text="@string/selectAPlanet"
android:textSize="10sp"
android:background="@android:drawable/btn_dropdown">
</Button>
在strings.xml
<string name="selectAPlanet">Select planet…</string>
<string-array name="planets__entries">
<item>The Sun with a name very long so long long long long longThe Sun with a name very long so long long long long longThe Sun with a name very long so long long long long long</item>
<item>Mercury</item>
<item>Venus</item>
<item>Earth</item>
<item>Mars</item>
<item>Jupiter</item>
<item>Saturn</item>
<item>Uranus</item>
<item>Neptune</item>
</string-array>
在MyFormActivity.java
public class MyFormActivity extends Activity {
@Override
public void onCreate(Bundle savedInstanceState) {
((Button) findViewById(R.id.btnSpinnerPlanets)).setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
final String[] items = view.getResources().getStringArray(R.array.planets__entries);
ArrayAdapter<String> adapter = new ArrayAdapter<String>(MyFormActivity.this, android.R.layout.simple_spinner_dropdown_item, items);
new AlertDialog.Builder(MyFormActivity.this).setTitle("the prompt").setAdapter(adapter, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
((Button) findViewById(R.id.btnSpinnerPlanets)).setText(items[which]);
dialog.dismiss();
}
}).create().show();
}
});
}
}
最后我获得了一个字体大小可配置无第一项可选择的按钮旋转器!!
感谢HRJ
