Question

我的ViewFlipper出现了奇怪的问题。除了一种特殊情况外，它的工作正常。当我第一次打开我的活动并点击第一张图片而不是滑动它时，应用程序显示错误。但是当我滑动它时，它的工作正常并显示下一个图像。在此之后，当我倒退到第一张图片并再次点击它时，它运作良好。

我的java代码：

import android.app.Activity;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
import android.view.animation.Animation;
import android.widget.ViewFlipper;

public class MyActivity extends Activity {

    ViewFlipper my_flipper;
    private float lastX;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_my_activity);

        my_flipper = (ViewFlipper) findViewById(R.id.my_flipper);
        showImages();
    }

    public void showImages () {
        my_flipper.setDisplayedChild(0);
        my_flipper.setOnTouchListener(new View.OnTouchListener() {
            @Override
            public boolean onTouch(View view, MotionEvent motionEvent) {
                switch (motionEvent.getAction()) {
                    case MotionEvent.ACTION_DOWN:
                        lastX = motionEvent.getX();
                        return true;
                    case MotionEvent.ACTION_UP:
                        float currentX = motionEvent.getX();
                        if (lastX < currentX) {
                            if (my_flipper.getDisplayedChild() == 0)
                                break;
                            my_flipper.setInAnimation(getApplication(), R.anim.slide_in_from_left);
                            my_flipper.setOutAnimation(getApplication(), R.anim.slide_out_to_right);
                            my_flipper.showNext();
                        }
                        if (lastX > currentX) {
                            if (my_flipper.getDisplayedChild() == 1) {
                                break;
                            }
                            my_flipper.setInAnimation(getApplication(), R.anim.slide_in_from_right);
                            my_flipper.setOutAnimation(getApplication(), R.anim.slide_out_to_left);
                            my_flipper.showPrevious();
                        }

                        my_flipper.getOutAnimation().setAnimationListener(new Animation.AnimationListener() {

                            public void onAnimationStart(Animation animation) {
                            }

                            public void onAnimationRepeat(Animation animation) {
                            }

                            public void onAnimationEnd(Animation animation) {

                            }
                        });
                }
                return true;
            }
        });
    }
}

和XML：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:app="http://schemas.android.com/apk/res-auto" android:layout_width="fill_parent"
    android:layout_height="fill_parent" android:background="#0f4b75"
    tools:context=".MyActivity">

    <ViewFlipper
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/my_flipper"
        android:background="#000000"
        >

        <ImageView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/atrakcja_0"
            android:adjustViewBounds="true"
            android:src="@drawable/foto"
            />

        <ImageView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/atrakcja_1"
            android:adjustViewBounds="true"
            android:src="@drawable/foto"
            />

        <ImageView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/atrakcja_2"
            android:adjustViewBounds="true"
            android:src="@drawable/foto"
            />

        <ImageView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/atrakcja_3"
            android:adjustViewBounds="true"
            android:src="@drawable/foto"
            />

    </ViewFlipper>

</RelativeLayout>

一个动画示例：

<set xmlns:android="http://schemas.android.com/apk/res/android"
    android:shareInterpolator="false">
    <translate
        android:fromXDelta="-100%" android:toXDelta="0%"
        android:fromYDelta="0%" android:toYDelta="0%"
        android:duration="140" />
</set>

最后记录：

W / dalvikvm：threadid = 1：线程退出时未捕获异常（group = 0x41ed5e00） E / AndroidRuntime：致命异常：主要过程：android.dedykowani_narciarze，PID：26403 显示java.lang.NullPointerException 在android.dedykowani_narciarze.MyActivity $ 1.onTouch（MyActivity.java:51）在android.view.View.dispatchTouchEvent（View.java:7729）在android.view.ViewGroup.dispatchTransformedTouchEvent（ViewGroup.java:2212）在android.view.ViewGroup.dispatchTouchEvent（ViewGroup.java:1945）在android.view.ViewGroup.dispatchTransformedTouchEvent（ViewGroup.java:2218）在android.view.ViewGroup.dispatchTouchEvent（ViewGroup.java:1959）在android.view.ViewGroup.dispatchTransformedTouchEvent（ViewGroup.java:2218）在android.view.ViewGroup.dispatchTouchEvent（ViewGroup.java:1959）在android.view.ViewGroup.dispatchTransformedTouchEvent（ViewGroup.java:2218）在android.view.ViewGroup.dispatchTouchEvent（ViewGroup.java:1959）在android.view.ViewGroup.dispatchTransformedTouchEvent（ViewGroup.java:2218）在android.view.ViewGroup.dispatchTouchEvent（ViewGroup.java:1959）在com.android.internal.policy.impl.PhoneWindow $ DecorView.superDispatchTouchEvent（PhoneWindow.java:2093）在com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent（PhoneWindow.java:1540）在android.app.Activity.dispatchTouchEvent（Activity.java:2500）在com.android.internal.policy.impl.PhoneWindow $ DecorView.dispatchTouchEvent（PhoneWindow.java:2041）在android.view.View.dispatchPointerEvent（View.java:7914）在android.view.ViewRootImpl $ ViewPostImeInputStage.processPointerEvent（ViewRootImpl.java:4165）在android.view.ViewRootImpl $ ViewPostImeInputStage.onProcess（ViewRootImpl.java:4044）在android.view.ViewRootImpl $ InputStage.deliver（ViewRootImpl.java:3556）在android.view.ViewRootImpl $ InputStage.onDeliverToNext（ViewRootImpl.java:3606）在android.view.ViewRootImpl $ InputStage.forward（ViewRootImpl.java:3575）在android.view.ViewRootImpl $ AsyncInputStage.forward（ViewRootImpl.java:3682）在android.view.ViewRootImpl $ InputStage.apply（ViewRootImpl.java:3583）在android.view.ViewRootImpl $ AsyncInputStage.apply（ViewRootImpl.java:3739）在android.view.ViewRootImpl $ InputStage.deliver（ViewRootImpl.java:3556）在android.view.ViewRootImpl $ InputStage.onDeliverToNext（ViewRootImpl.java:3606）在android.view.ViewRootImpl $ InputStage.forward（ViewRootImpl.java:3575）在android.view.ViewRootImpl $ InputStage.apply（ViewRootImpl.java:3583）在android.view.ViewRootImpl $ InputStage.deliver（ViewRootImpl.java:3556）在android.view.ViewRootImpl.deliverInputEvent（ViewRootImpl.java:5750）在android.view.ViewRootImpl.doProcessInputEvents（ViewRootImpl.java:5730）在android.view.ViewRootImpl.enqueueInputEvent（ViewRootImpl.java:5701）在android.view.ViewRootImpl $ WindowInputEventReceiver.onInputEvent（ViewRootImpl.java:5830）在android.view.InputEventReceiver.dispatchInputEvent（InputEventReceiver.java:185）在android.os.MessageQueue.nativePollOnce（本机方法）在android.os.MessageQueue.next（MessageQueue.java:138）在android.os.Looper.loop（Looper.java:123）在android.app.ActivityThread.main（ActivityThread.java:5333） at java.lang.reflect.Method.invokeNative（Native Method）在java.lang.reflect.Method.invoke（Method.java:515）在com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit.java:895）在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:711）在dalvik.system.NativeStart.main（本地方法）

此行产生错误：

my_flipper.getOutAnimation().setAnimationListener(new Animation.AnimationListener() {

我将非常感谢您提供的任何帮助。

ViewFlipper - 点击图片

0 个答案: