android - NumberPicker 在 setValue() 后显示错误值

Question

我试图创建一个 NumberPicker 来满足我的需要，但我偶然发现了一些东西，但我不明白它是什么。

行为很简单，我有三个数字选择器，每个选择器的值都在 -15 到 15 之间；当用户按下 Ok 按钮时，为方便起见，所选值(如果有效)将保存在“结构”和 SharedPreferences 中。

问题显示在 this screenshot 中.

当我保存一个不是 -1 的数字时，它可以正常工作。如果我保存 -1，结果就是上面那个(它发生在每个数字选择器中)。
即使显示 -15，实际存储的值是 -1:高于和低于 -15 的值是正确的，如果我滑动一个像素，值变为 -1，在 OnClick 中，解析的值是 -1以及由

返回的值

value < 0 ? value + maxValue + 1 : value - 1

在 setPickers() 中是正确的(29，数组的最后一个索引)。

我尝试将各种初始化移动到代码的不同部分，并使其在三个设备上运行；两个物理(使用 Android 5.0.2 和 5.1.1)和一个使用 Android Studio 模拟(使用 KitKat 图像)，问题总是出现。
现在我开始认为，要么我错过了一些非常基本的东西，要么恰恰相反。

感谢您提供的任何帮助。

.java:

public class CoefficientsDialog extends DialogFragment {

    private Activity activity;
    private MyView myView;
    private AlertDialog alertDialog;
    private AlertDialog.Builder builder;
    private NumberPicker startPicker, endPicker, stepPicker;

    final private String C     = "C_Coefficient";
    final private String Gamma = "Gamma_Coefficient";

    private String cStartKey;
    private String cEndKey;
    private String cStepKey;
    private String gStartKey;
    private String gEndKey;
    private String gStepKey;

    String[] defaultValues = new String[]{
            "1", "2", "3", "4", "5", "6", "7", "8", "9", "10", "11",
            "12", "13", "14", "15", "-15", "-14", "-13", "-12", "-11",
            "-10", "-9", "-8", "-7", "-6", "-5", "-4", "-3", "-2", "-1"
    };

    final int minValue = 0;
    final int maxValue = defaultValues.length - 1;

    private SharedPreferences settings;

    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState) {
        final String tag = getTag();


        cStartKey   = getString(R.string.c_start_key);
        cEndKey     = getString(R.string.c_end_key);
        cStepKey    = getString(R.string.c_step_key);
        gStartKey   = getString(R.string.g_start_key);
        gEndKey     = getString(R.string.g_end_key);
        gStepKey    = getString(R.string.g_step_key);

        activity    = getActivity();
        settings    = PreferenceManager.getDefaultSharedPreferences(activity);
        builder     = new AlertDialog.Builder(activity);
        myView      = new MyView(activity);

        setPickers();

        switch (tag) {
            case (C):
                String cTitle = "C coefficient range";
                init(cTitle, tag);
                break;
            case (Gamma):
                String gTitle = "Gamma coefficient range";
                init(gTitle, tag);
                break;
            default:
                dismiss();
                break;
        }

        return alertDialog;
    }

    private void init(String title, final String tag) {
        builder
                .setView(myView)
                .setTitle(title)
                .setPositiveButton("Ok", null)
                .setNegativeButton("Back", null);

        alertDialog = builder.create();

        alertDialog.setOnShowListener(new DialogInterface.OnShowListener() {
            @Override
            public void onShow(final DialogInterface dialog) {

                Button button = alertDialog.getButton(AlertDialog.BUTTON_POSITIVE);

                button.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                        int start   = startPicker.getValue();
                        int end     = endPicker.getValue();
                        int step    = stepPicker.getValue();
                        int middle  = defaultValues.length / 2;

                        // The index is different from the actual value, method valid only if the
                        // array is antisymmetric
                        start = start <= middle ? start + 1 : start - maxValue - 1;
                        end   = end   <= middle ? end   + 1 : end   - maxValue - 1;
                        step  = step  <= middle ? step  + 1 : step  - maxValue - 1;

                        // If true, the user is trying to go from a positive value to a negative
                        // value with a positive step or vice versa
                        if ((end - start) / step < 0)
                            Toast.makeText(activity, R.string.wrong_direction, Toast.LENGTH_SHORT)
                                    .show();
                            // If true, start + (n * step) isn't equal to end given any value of n
                        else if ((end - start) % step != 0)
                            Toast.makeText(activity, R.string.step_inadequate, Toast.LENGTH_SHORT)
                                    .show();
                        else if (end == start)
                            Toast.makeText(activity, R.string.one_value_validation,
                                    Toast.LENGTH_SHORT)
                                    .show();
                        else {
                            savePreferences(tag, start, end, step);
                            alertDialog.dismiss();
                        }
                    }
                });
            }
        });
    }

    private void savePreferences(final String tag, int start, int end, int step) {

        SharedPreferences.Editor editor = settings.edit();

        switch (tag) {
            case (C): {
                ModelingStructure.cStart = start;
                ModelingStructure.cEnd   = end;
                ModelingStructure.cStep  = step;

                editor.putInt(cStartKey, start);
                editor.putInt(cEndKey, end);
                editor.putInt(cStepKey, step);
                editor.apply();
                break;
            }
            case (Gamma): {
                ModelingStructure.gStart = start;
                ModelingStructure.gEnd   = end;
                ModelingStructure.gStep  = step;

                editor.putInt(gStartKey, start);
                editor.putInt(gEndKey, end);
                editor.putInt(gStepKey, step);
                editor.apply();
                break;
            }
        }
    }

    private void setPickers() {
        // Initialize startPicker
        startPicker = (NumberPicker) myView.findViewById(R.id.cStartPicker);
        startPicker.setMaxValue(maxValue);
        startPicker.setMinValue(minValue);
        startPicker.setDisplayedValues(defaultValues);

        // Initialize endPicker
        endPicker = (NumberPicker) myView.findViewById(R.id.cEndPicker);
        endPicker.setMinValue(minValue);
        endPicker.setMaxValue(maxValue);
        endPicker.setDisplayedValues(defaultValues);

        // Initialize stepPicker
        stepPicker = (NumberPicker) myView.findViewById(R.id.cStepPicker);
        stepPicker.setMinValue(minValue);
        stepPicker.setMaxValue(maxValue);
        stepPicker.setDisplayedValues(defaultValues);

        // Check if the pickers were previously changed
        int start = settings.getInt(cStartKey, 1);
        int end   = settings.getInt(cEndKey, 1);
        int step  = settings.getInt(cStepKey, 1);

        // The index is different from the actual value
        startPicker.setValue(start < 0 ? start + maxValue + 1 : start - 1);
        endPicker.setValue  (end   < 0 ? end   + maxValue + 1 : end   - 1);
        stepPicker.setValue (step  < 0 ? step  + maxValue + 1 : step  - 1);
    }

    public void showDialog() {
        alertDialog.show();
    }
[...]
}

.xml:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="horizontal" android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_gravity="center">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/c_start"
        android:id="@+id/cStartView"
        android:layout_alignStart="@+id/cStartPicker"
        android:layout_alignEnd="@+id/cStartPicker"
        android:gravity="center_horizontal" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/c_end"
        android:id="@+id/cEndView"
        android:layout_alignStart="@+id/cEndPicker"
        android:layout_alignEnd="@+id/cEndPicker"
        android:gravity="center_horizontal" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/c_step"
        android:id="@+id/cStepView"
        android:gravity="center_horizontal"
        android:layout_alignStart="@+id/cStepPicker"
        android:layout_alignEnd="@+id/cStepPicker" />


    <NumberPicker
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/cEndPicker"
        android:layout_centerInParent="true" />

    <NumberPicker
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/cStartPicker"
        android:layout_centerInParent="true"
        android:layout_toStartOf="@id/cEndPicker"
        android:layout_marginEnd="10dp" />

    <NumberPicker
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/cStepPicker"
        android:layout_centerInParent="true"
        android:layout_toEndOf="@id/cEndPicker"
        android:layout_marginStart="10dp" />

</RelativeLayout>

Answer 1

我遇到了类似的问题。我使用 scrollBy() 方法以编程方式设置数字选择器的值，并且在其中两个值上显示了错误的数字。经过一些调查后，我意识到 NumberPicker 的 onTouch 中有一些代码，在以编程方式设置值时没有被调用。

所以我在设置一个值后立即模拟触摸。

public void changeValueByOne(final boolean increment) {

    int scrollStep = getHeight() / 3;

    scrollBy(0, increment ? scrollStep : (-1 * scrollStep));

    simulateTouchHack();
}

private void simulateTouchHack() {
    MotionEvent motionEventDown = MotionEvent.obtain(
            SystemClock.uptimeMillis(),
            SystemClock.uptimeMillis() + 100,
            MotionEvent.ACTION_DOWN,
            getWidth() / 2,
            getHeight() / 2,
            0
    );

    dispatchTouchEvent(motionEventDown);

    MotionEvent motionEventUp = MotionEvent.obtain(
            SystemClock.uptimeMillis() + 200,
            SystemClock.uptimeMillis() + 300,
            MotionEvent.ACTION_UP,
            getWidth() / 2,
            getHeight() / 2,
            0
    );

    dispatchTouchEvent(motionEventUp);
}