当用户位于ScrollView的末尾时,我想检测到它并加载一些新项目。我已经完成了,但是看来我使用的功能不适用于某些旧版本的Android。
我有这个代码:
scrollView = (ScrollView) findViewById(R.id.scrollView);
scrollView.setOnScrollChangeListener(new ScrollListener(this));
然后 :
@TargetApi(Build.VERSION_CODES.M)
public class ScrollListener implements View.OnScrollChangeListener {
ScrollingActivity context;
public ScrollListener(ScrollingActivity context) {
this.context = context;
}
@Override
public void onScrollChange(View v, int scrollX, int scrollY, int oldScrollX, int oldScrollY) {
ScrollView scrollView = (ScrollView) v;
View view = (View) scrollView.getChildAt(scrollView.getChildCount() - 1);
int diff = (view.getBottom() - (scrollView.getHeight() + scrollY));
int oldDiff = (view.getBottom() - (scrollView.getHeight() + oldScrollY));
// Si on a atteint le bas de la scrollView et qu'on était en train de descendre
if(diff == 0 && oldDiff > 0) {
context.endOfScroll(); // function I call to load data...
}
}}
我有这个错误:
08-19 21:27:35.135 26504-26504/com.histoire_horreur E/AndroidRuntime: FATAL EXCEPTION: main
java.lang.NoClassDefFoundError: com.histoire_horreur.Listener.ScrollListener
at com.histoire_horreur.MainActivity.createView(MainActivity.java:59)
at com.histoire_horreur.MainActivity.onCreate(MainActivity.java:47)
at android.app.Activity.performCreate(Activity.java:5122)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1150)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2315)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2403)
at android.app.ActivityThread.access$600(ActivityThread.java:165)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1373)
at android.os.Handler.dispatchMessage(Handler.java:107)
at android.os.Looper.loop(Looper.java:194)
at android.app.ActivityThread.main(ActivityThread.java:5391)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:525)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:833)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600)
at dalvik.system.NativeStart.main(Native Method)
就像我说的那样,这段代码在某些版本的Android上可以正常运行,但在我的Wiko 4.2.2上却不能。
我的错误和这里相同:https://forums.xamarin.com/discussion/62241/problem-setting-on-scroll-listener-to-android-horizontal-scroll-view-class-not-found-exception
解决方案是使用ViewTreeObserver,但是,当滚动在底部时,我无法成功检测到。我试图这样做:
scrollView = (ScrollView) findViewById(R.id.scrollView);
scrollView.getViewTreeObserver().addOnScrollChangedListener(new ViewTreeObserver.OnScrollChangedListener() {
@Override
public void onScrollChanged() {
// How to get X, Y, Old X and Old Y ?
}
});
但是我无法获取scrollX,scrollY,oldScrollX和oldScrollY。
您知道一种使其在所有版本的Android上都能正常工作的方法吗?
最佳答案
我有同样的问题。
如果您使用ViewTreeObserver,则代码将正常运行,没有异常(exception),唯一的问题是在底部滚动 View 时检测到。
此代码段可以帮助您:
@Override
public void onScrollChanged() {
View v = myScrollView.getChildAt(myScrollView.getChildCount() - 1);
int diff = (v.getBottom() - (myScrollView.getHeight() + myScrollView.getScrollY()));
if (diff <= 0) {
//load data here, there is bottom of scrollview
}
}
关于android - ScrollView上的setOnScrollChangeListener : Error,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/39578196/