How to reset data of NumberPicker

Question 1

Well, I look into the source code of NumberPicker.java, find that it will recompute the data and refresh UI in setMinValue(int minValue) and setMaxValue(int minValue). When set the new minValue, it will compute using new minValue and old maxValue, then error occured.

So, I modify a little of the NumberPicker: set value only in setMinValue(int minValue) and setMaxValue(int maxValue), and update UI in setDisplayedValues(String[] displayedValues). When data of NumberPicker changed, just reset the minValue、maxVaule and displayedValues. Note that setDisplayedValues(String[] displayedValues) MUST be called at last.

Here is what I modified:

NumberPicker.java:

public void setMinValue(int minValue) {
    if (mMinValue == minValue) {
        return;
    }
    if (minValue < 0) {
        throw new IllegalArgumentException("minValue must be >= 0");
    }
    mMinValue = minValue;
    if (mMinValue > mValue) {
        mValue = mMinValue;
    }
    //boolean wrapSelectorWheel = mMaxValue - mMinValue > mSelectorIndices.length;
    //setWrapSelectorWheel(wrapSelectorWheel);
    //initializeSelectorWheelIndices();
    //updateInputTextView();
    //tryComputeMaxWidth();
    invalidate();
}

public void setMaxValue(int maxValue) {
    if (mMaxValue == maxValue) {
        return;
    }
    if (maxValue < 0) {
        throw new IllegalArgumentException("maxValue must be >= 0");
    }
    mMaxValue = maxValue;
    if (mMaxValue < mValue) {
        mValue = mMaxValue;
    }
    //boolean wrapSelectorWheel = mMaxValue - mMinValue > mSelectorIndices.length;
    //setWrapSelectorWheel(wrapSelectorWheel);
    //initializeSelectorWheelIndices();
    //updateInputTextView();
    //tryComputeMaxWidth();
    invalidate();
}

public void setDisplayedValues(String[] displayedValues) {
    if (mDisplayedValues == displayedValues) {
        return;
    }
    mDisplayedValues = displayedValues;
    if (mDisplayedValues != null) {
        // Allow text entry rather than strictly numeric entry.
        mInputText.setRawInputType(InputType.TYPE_CLASS_TEXT
                | InputType.TYPE_TEXT_FLAG_NO_SUGGESTIONS);
    } else {
        mInputText.setRawInputType(InputType.TYPE_CLASS_NUMBER);
    }
    boolean wrapSelectorWheel = mMaxValue - mMinValue > mSelectorIndices.length;
    setWrapSelectorWheel(wrapSelectorWheel);
    updateInputTextView();
    initializeSelectorWheelIndices();
    tryComputeMaxWidth();
}

AreaPickerDialog.java:

private void initCityData(int provinceId) {
    List<Arealist> cities = mAreaUtil.getCityListOfProvince(provinceId);
    if (cities != null && cities.size() > 0) {
        try {
            int min = Integer.parseInt(cities.get(0).getAreaid());
            int max = Integer.parseInt(cities.get(cities.size() -1).getAreaid());
            String[] cityNames = new String[cities.size()];
            for (int i = 0; i < cityNames.length; i++) {
                cityNames[i] = cities.get(i).getName();
            }
            mCityPicker.setMinValue(min);
            mCityPicker.setMaxValue(max);
            mCityPicker.setDisplayedValues(cityNames);
        } catch (NumberFormatException e) {
            ILog.e(TAG, e.getMessage(), e);
        }
    }
}

This is an ugly but working solution.

Question 2

check for Call setDisplayedValues(null) before setMaxValue in onClick.

Reference: https://stackoverflow.com/a/24322319/2624806

Question 3

I have the same problem and I fixed it without modifing NumberPicker.java. Here is the code for your reference.

private void initCityData(int provinceId) {
        List<Arealist> cities = mAreaUtil.getCityListOfProvince(provinceId);
        if (cities != null && cities.size() > 0) {
            try {
                int min = Integer.parseInt(cities.get(0).getAreaid());
                int max = Integer.parseInt(cities.get(cities.size() -1).getAreaid());
                String[] cityNames = new String[cities.size()];
                for (int i = 0; i < cityNames.length; i++) {
                    cityNames[i] = cities.get(i).getName();
                }
                int maxV = mCityPicker.getMaxValue();
                if (max> maxV){ 
                    mCityPicker.setMinValue(min);
                    mCityPicker.setValue(0);
                    mCityPicker.setDisplayedValues(cityNames);
                    mCityPicker.setMaxValue(max);
                }else{
                    mCityPicker.setMinValue(min);
                    mCityPicker.setValue(0);
                    mCityPicker.setMaxValue(max);
                    mCityPicker.setDisplayedValues(cityNames);
                }

            } catch (NumberFormatException e) {
                ILog.e(TAG, e.getMessage(), e);
            }
        }
    }

Question 4

Just set displayedValues to null before resetting number picker like below:

 pickerWard.displayedValues = null

 pickerWard.maxValue = values.size - 1
 pickerWard.displayedValues = values

Question 5

looking the code of NumberPicker you're using:

private boolean updateInputTextView() {
/*
* If we don't have displayed values then use the current number else
* find the correct value in the displayed values for the current
* number.
*/
        String text = (mDisplayedValues == null) ? formatNumber(mValue)
                : mDisplayedValues[mValue - mMinValue];

you can see that's using mMinValue before you call setMinValue.

Try setting minValue and maxValue, before set the displayed values.