Question

在这里提出这个问题之前，我已经做了很多谷歌搜索。

我已经在我的Recyclerview中集成了NativeExpressAdView，如本google example中所述，它也正常工作。但问题是，在这个示例项目中，他们是从第0个位置添加NativeExpressAdView，但是不想在第0个位置添加NativeExpressAdView。

我也可以随机添加位置，但是当我们必须从代码中为NativeExpressAdView设置adsize时会出现问题。

使用MainActivity setUpAndLoadNativeExpressAds方法访问的Cardview将为Null，如果不在第零位添加视图，则会给NPE。

这是我修改过的代码段

/**
     * Adds Native Express ads to the items list.
     */
    private void addNativeExpressAds() {

        // Loop through the items array and place a new Native Express ad in every ith position in
        // the items List.
        for (int i = 7; i <= mRecyclerViewItems.size(); i += ITEMS_PER_AD) {
            final NativeExpressAdView adView = new NativeExpressAdView(MainActivity.this);
            mRecyclerViewItems.add(i, adView);
        }
    }

    /**
     * Sets up and loads the Native Express ads.
     */
    private void setUpAndLoadNativeExpressAds() {
        // Use a Runnable to ensure that the RecyclerView has been laid out before setting the
        // ad size for the Native Express ad. This allows us to set the Native Express ad's
        // width to match the full width of the RecyclerView.
        mRecyclerView.post(new Runnable() {
            @Override
            public void run() {
                final float scale = MainActivity.this.getResources().getDisplayMetrics().density;
                // Set the ad size and ad unit ID for each Native Express ad in the items list.
                for (int i = 7; i <= mRecyclerViewItems.size(); i += ITEMS_PER_AD) {
                    final NativeExpressAdView adView =
                            (NativeExpressAdView) mRecyclerViewItems.get(i);
                    final CardView cardView = (CardView) findViewById(R.id.ad_card_view);
                    final int adWidth = cardView.getWidth() - cardView.getPaddingLeft()
                            - cardView.getPaddingRight(); //Here cardView will be Null (so NPE).
                    AdSize adSize = new AdSize((int) (adWidth / scale), NATIVE_EXPRESS_AD_HEIGHT);
                    adView.setAdSize(adSize);
                    adView.setAdUnitId(AD_UNIT_ID);
                }

                // Load the first Native Express ad in the items list.
                loadNativeExpressAd(7); //Not added code for this method as nothing is modified in that.
            }
        });
    }

即使我从repo中提取示例项目代码后实现了相同的更改，也会出现此问题。

这是我的logcat崩溃

    FATAL EXCEPTION: main
java.lang.NullPointerException                                                                                                                           at com.google.android.gms.example.nativeexpressrecyclerviewexample.MainActivity$1.run(MainActivity.java:106)
at android.os.Handler.handleCallback(Handler.java:725)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:5041)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
at dalvik.system.NativeStart.main(Native Method)

这是某种错误，或者我做错了什么。

Answer 1

再添加一个

条件

if (i!=0){}

两个for循环中的

的更新：

*/ private void addNativeExpressAds() { // Loop through the items array and place a new Native Express ad in every ith position in // the items List. for (int i = 0; i <= mRecyclerViewItems.size(); i += ITEMS_PER_AD) { if(i!=0){ final NativeExpressAdView adView = new NativeExpressAdView(MainActivity.this); mRecyclerViewItems.add(i, adView); }} } /** * Sets up and loads the Native Express ads. */ private void setUpAndLoadNativeExpressAds() { // Use a Runnable to ensure that the RecyclerView has been laid out before setting the // ad size for the Native Express ad. This allows us to set the Native Express ad's // width to match the full width of the RecyclerView. mRecyclerView.post(new Runnable() { @Override public void run() { final float scale = MainActivity.this.getResources().getDisplayMetrics().density; // Set the ad size and ad unit ID for each Native Express ad in the items list. for (int i = 0; i <= mRecyclerViewItems.size(); i += ITEMS_PER_AD) { if(i!=0){ final NativeExpressAdView adView = (NativeExpressAdView) mRecyclerViewItems.get(i); final CardView cardView = (CardView) findViewById(R.id.ad_card_view); final int adWidth = cardView.getWidth() - cardView.getPaddingLeft() - cardView.getPaddingRight(); //Here cardView will be Null (so NPE). AdSize adSize = new AdSize((int) (adWidth / scale), NATIVE_EXPRESS_AD_HEIGHT); adView.setAdSize(adSize); adView.setAdUnitId(AD_UNIT_ID); }} // Load the first Native Express ad in the items list. loadNativeExpressAd(ITEMS_PER_AD); //Not added code for this method as nothing is modified in that. } }); }

Recyclerview实施中的Admob NativeExpressAdView问题

1 个答案: