如何在ViewPage中设置toast

Question

我正试图在我的PagerAdapter类中设置toast，但它显示错误，因为com.example.neelaysrivastava.batmanvsupermanwallpaper.MainActivity不是一个封闭类。如果我在我的PagerAdapter中更改.what，我会遇到错误，因为toast不是一个封闭类。“

 package com.example.neelaysrivastava.batmanvsupermanwallpaper;

 import android.app.WallpaperManager;
 import android.content.Context;
 import android.content.res.Resources;
 import android.graphics.Bitmap;
 import android.graphics.BitmapFactory;
  import android.support.v4.view.PagerAdapter;
 import android.view.LayoutInflater;
  import android.view.View;
 import android.view.ViewGroup;
 import android.widget.Button;
 import android.widget.ImageView;
 import android.widget.LinearLayout;
 import android.widget.Toast;

 import java.io.IOException;


 class CustomeSwipeAdapter extends PagerAdapter {
private Context ctx;
private int[] imgID ={R.drawable.img1,R.drawable.img2,R.drawable.img3,R.drawable.img4,R.drawable.img5,R.drawable.img6,
        R.drawable.img7,R.drawable.img8,R.drawable.img9,R.drawable.img10,R.drawable.img11,R.drawable.img12,R.drawable.img13,
        R.drawable.img14,R.drawable.img15,R.drawable.img16,R.drawable.img17,R.drawable.img18,R.drawable.img19,
        R.drawable.img20,R.drawable.img21,R.drawable.img22,R.drawable.img23,R.drawable.img24,R.drawable.img25,R.drawable.img26,
        R.drawable.img27,R.drawable.img28,R.drawable.img29,R.drawable.img30,R.drawable.img31,R.drawable.img32,R.drawable.img33,
        R.drawable.img34,R.drawable.img35,R.drawable.img36,R.drawable.img37,R.drawable.img38
};
private LayoutInflater layoutInflater;
public CustomeSwipeAdapter(Context ctx) {
    this.ctx=ctx;
}

@Override
public int getCount() {
    return imgID.length;
}

@Override
public boolean isViewFromObject(View view, Object object) {
    return (view==(LinearLayout)object);
}
Bitmap goal;
@Override
public Object instantiateItem(ViewGroup container, final int position) {
    layoutInflater=(LayoutInflater)ctx.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    View item_view =layoutInflater.inflate(R.layout.extra,container,false);
    ImageView imageView =(ImageView)item_view.findViewById(R.id.imageView);
    Button button=(Button)item_view.findViewById(R.id.button);
    imageView.setImageResource(imgID[position]);
    button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Toast.makeText(ctx.getBaseContext(), "wallpaper set", Toast.LENGTH_SHORT).show();
            BitmapFactory.decodeResource(Resources.getSystem(), imgID[position]);
            WallpaperManager wallpaperManager =
                    WallpaperManager.getInstance(ctx.getApplicationContext());
            try {
                int height = wallpaperManager.getDesiredMinimumHeight();
                int width = wallpaperManager.getDesiredMinimumWidth();
                Bitmap bm =
                        BitmapFactory.decodeResource(v.getContext().getResources(), imgID[position]);
                goal = Bitmap.createScaledBitmap(bm, width, height, true);
                v.getContext().getResources().getDrawable(imgID[position]);
                wallpaperManager.setBitmap(goal);
            } catch (IOException e) {
                e.printStackTrace();
            }

        }
    });
    container.addView(item_view);
    return item_view;

}

@Override
public void destroyItem(ViewGroup container, int position, Object object) {
    container.removeView((LinearLayout) object);
}

}

Answer 1

虽然你没有提供足够的代码，但根据经验，我认为原因可能是

1. 或者您没有在清单文件

中提到所谓的活动

2.您没有为各自的toast提供上下文，如果它是一个子类，请尝试传递上下文

1. 或者也许你可以改变这行

Toast.makeText(Main3Activity.this, "wallpaper set", Toast.LENGTH_SHORT).show();

至

    `Toast.makeText(getBaseContext(), "wallpaper set", Toast.LENGTH_SHORT).show();`