Android Number Picker设3个选项时无法选中值2的修复请求

问题根源 #

你遇到的异常是因为代码中存在一个非法操作：在已经将minValue设为1的情况下，调用selectMarkerNumPicker.setValue(0)设置了一个超出范围的值。虽然系统不会直接崩溃，但这会打乱NumberPicker的内部状态逻辑，当范围刚好是1-3三个选项时，这种状态混乱就会表现为无法选中中间的数值2。

修复方案 #

移除代码中多余的setValue(0)操作，调整范围时直接设置合法的min、max值，再指定目标选中值即可。

修复后的数值递增代码

// Get the maximum marker number picker value and increment in prep
// for the new marker.
Integer routes_num = selectMarkerNumPicker.getMaxValue();
routes_num += 1;

// Add 1 to current waypoint total value for this route.
int route = selectRouteNumPicker.getValue();
route_count_string[route - 1] = String.valueOf(Integer.valueOf(route_count_string[route - 1]) + 1);

// Set number picker to new/last marker position.
selectMarkerNumPicker.setMinValue(1);
selectMarkerNumPicker.setMaxValue(routes_num);
selectMarkerNumPicker.setValue(routes_num);

修复后的数值递减代码

// Always delete the last Marker.
Integer marker_num = selectMarkerNumPicker.getMaxValue();
marker_num -= 1;

Integer route_num = selectRouteNumPicker.getValue();

// If this is the last marker in a route do not delete it.  Instead tell
// user to delete route.
if(route_count_string[route_num - 1].equals("1"))
{
    // This is the last marker in a route. Do not delete it.  Instead tell
    // user to delete route.
    Toast.makeText(getApplicationContext(), "Can't Delete Last Marker\nDelete Route Instead", Toast.LENGTH_SHORT).show();
}
else
{
    // Set number picker to new/last marker position.
    selectMarkerNumPicker.setMinValue(1);
    selectMarkerNumPicker.setMaxValue(marker_num);
    selectMarkerNumPicker.setValue(marker_num);
}

修复说明 #

NumberPicker不允许设置超出[minValue, maxValue]范围的数值，之前的setValue(0)属于非法操作，会导致控件内部的布局、选中状态逻辑紊乱。移除该操作后，控件状态始终保持合法，1-3范围下的数值2就能正常选中了。

内容的提问来源于stack exchange，提问作者st2000