Android - NumberPicker with custom string data shows wrong value?

Question

It is so simple, and it is so hard at the same time.

MainActivity.java

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    String[] values = {"d", "aa", "a", "b"};
    NumberPicker numberPicker = findViewById(R.id.number_picker);
    numberPicker.setDisplayedValues(values);
    numberPicker.setMinValue(0);
    numberPicker.setMaxValue(3);
    numberPicker.setValue(2); // Want to show "a" in number picker
}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">
    <NumberPicker
        android:id="@+id/number_picker"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:descendantFocusability="blocksDescendants"
        app:layout_constraintTop_toTopOf="parent" />
</android.support.constraint.ConstraintLayout>

Result

Some more cases:

1. If values are {"d", "c", "a", "b"}, the result is "a".
2. If values are {"d", "aaaaa", "a", "b"}, the result is "aaaaaa".
3. If values are {"d", "aa", "c", "b"}, the result is "c".
4. If values are {"d", "b", "a", "aa"}, the result is "a".
5. If values are {"d", "AA", "a", "c"}, the result is "AA".
6. If values are {"d", "ABCDAA, "a", "c"}, the result is "ABCDAA".

And when I click to anywhere inside the number picker, the "aa"'ish becomes "a" as expected. However, try putting numberPicker.performClick() after the setValue(2) method won't help.

This looks so simple but it is driving me nuts. Please help me.

Answer 1

tyr to create your own function to modify the data to be set on NumberPicker before set on NumberPicker.This function prevents any string to be substring of any string from the given array to be set on NumberPicker

modifyDataForNumberPicker(values);
numberPicker.setDisplayedValues(values);

private void modifyDataForNumberPicker(String[] dataList){
        int i=0;
        for(String data : dataList){
            int pos = i++;
            dataList[pos] = data+" ";
    }
} 

the get the value clicked in the NumberPicker

numberPicker.setOnValueChangedListener(new NumberPicker.OnValueChangeListener() {
    @Override
    public void onValueChange(NumberPicker picker, int oldVal, int newVal) {
    String selectedvalue = values[newVal]           
    }
});