小编Nav*_*sal的帖子

我正在努力学习Kotlin.是什么 val,var和internalKotlin相比,Java？

在Java中:

 RadioGroup radioGroup;
 RadioButton button;
 Button submit;

转换后显示:

 internal var radioGroup: RadioGroup
 internal var button: RadioButton
 internal var submit: Button

我点击RecyclerView项目时想打开对话框.单击显示在屏幕上但没有打开对话框后,Toast正在工作.

码:

  public class Gridview_adapter extends RecyclerView.Adapter<Gridview_adapter.Myholder> {


    private ArrayList<Photos_model> list;
    private Activity ctx;


    public Gridview_adapter(Activity ctx, ArrayList<Photos_model> list) {
        this.list = list;
        this.ctx = ctx;
    }

    @Override
    public Gridview_adapter.Myholder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.custom_gridview, parent, false);
        return new Gridview_adapter.Myholder(view);
    }

    @Override
    public void onBindViewHolder(Gridview_adapter.Myholder holder, int position) {

        final Photos_model id = list.get(position);

        Picasso.with(ctx).load(list.get(position).getImage()).resize(250, 400).into(holder.image);

        holder.itemView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {


                Toast.makeText(ctx, "Selecteddddddddddddd upper", Toast.LENGTH_SHORT).show();


                final Dialog dialog = new …

我在 API 级别 19 (Kitkat) 中遇到错误，它在 API 23 及更高版本中运行良好。我还在 gradle 文件和 multidex 依赖项中启用了 MultiDex。但它不起作用。请给我一个解决方案。代码在这里：

              java.lang.RuntimeException: Unable to get provider com.google.firebase.provider.FirebaseInitProvider: java.lang.ClassNotFoundException: Didn't find class "com.google.firebase.provider.FirebaseInitProvider" on path: DexPathList[[zip file "/system/framework/com.google.android.maps.jar", zip file "/data/app/com.trackawesome-2.apk"],nativeLibraryDirectories=[/data/app-lib/com.trackawesome-2, /vendor/lib, /system/lib]]
                                                                    at android.app.ActivityThread.installProvider(ActivityThread.java:5011)
                                                                    at android.app.ActivityThread.installContentProviders(ActivityThread.java:4582)
                                                                    at android.app.ActivityThread.handleBindApplication(ActivityThread.java:4522)
                                                                    at android.app.ActivityThread.access$1500(ActivityThread.java:151)
                                                                    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1381)
                                                                    at android.os.Handler.dispatchMessage(Handler.java:110)
                                                                    at android.os.Looper.loop(Looper.java:193)
                                                                    at android.app.ActivityThread.main(ActivityThread.java:5292)
                                                                    at java.lang.reflect.Method.invokeNative(Native Method)
                                                                    at java.lang.reflect.Method.invoke(Method.java:515)
                                                                    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:824)
                                                                    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:640)
                                                                    at dalvik.system.NativeStart.main(Native Method)
                                                                 Caused by: java.lang.ClassNotFoundException: Didn't find class "com.google.firebase.provider.FirebaseInitProvider" on path: DexPathList[[zip file "/system/framework/com.google.android.maps.jar", zip file "/data/app/com.trackawesome-2.apk"],nativeLibraryDirectories=[/data/app-lib/com.trackawesome-2, /vendor/lib, /system/lib]] …