您必须将最后选择的位置保存NumberPicker
到SharedPreferences
。之后,每次打开NumberPicker
时,都应使用void setValue (int value)为其设置默认选择位置
final String[] power = { "0.00", "0.25", "0.50", "0.75s", "1.00s" };
NumberPicker numberPicker = (NumberPicker) findViewById(R.id.numberPicker);
numberPicker.setMinValue(0);
numberPicker.setMaxValue(power.length - 1);
numberPicker.setDisplayedValues(power);
numberPicker.setOnValueChangedListener(new NumberPicker.OnValueChangeListener() {
@Override
public void onValueChange(NumberPicker picker, int oldVal, int newVal) {
// any time your number picker change, we will save it to SharedPreferences
saveIntToSharedPreferences(mContext, PREF_NUMBER_PICKER_LAST_SELECTED_POSITION, newVal);
}
});
// when we open screen, we will select the last selected value by use setValue(...)
numberPicker.setValue(
getIntFromSharedPreferences(mContext, PREF_NUMBER_PICKER_LAST_SELECTED_POSITION));
用于保存/获取整数的辅助函数SharedPreferences
private void saveIntToSharedPreferences(Context context, String key, int value) {
SharedPreferences sharedPreferences =
PreferenceManager.getDefaultSharedPreferences(context);
SharedPreferences.Editor editor = sharedPreferences.edit();
editor.putInt(key, value);
editor.apply();
}
private int getIntFromSharedPreferences(Context context, String key) {
SharedPreferences sharedPreferences =
PreferenceManager.getDefaultSharedPreferences(context);
return sharedPreferences.getInt(key, 0);
}