Question

我收到此错误：

Description Resource    Path    Location    Type
Swipeactivity cannot be resolved to a variable  SwipeActivity.java  /Copy of TD GridView/src/com/td/gridview    line 32 Java Problem

代码

int[] icons = MainActivity.ICONS;    

    //get image position

    Intent n = getIntent();
    int position= n.getIntExtra("id", position);

    ViewPager viewPager = (ViewPager) findViewById(R.id.view_pager);
    ImagePagerAdapter adapter = new ImagePagerAdapter(Swipeactivity, icons[position]);
    viewPager.setAdapter(adapter);
    viewPager.setCurrentItem(position);

这一行的问题：

ImagePagerAdapter adapter = new ImagePagerAdapter(Swipeactivity, icons[position]);

Swipeactivity cannot be resolved to a variable

那么如何将Swipeactivity类传递给上下文变量？

像：

context = swipeactivity;

所以可以像

一样使用它

ImagePagerAdapter adapter = new ImagePagerAdapter(Context , icons[position]);

请参阅this link这取决于我之前的问题，它会帮助您理解

经过太多错误后我终于得到了答案而且非常简单......;）

// get intent data
    Intent i = getIntent();

    // Selected image id
    int position = i.getExtras().getInt("id");

ViewPager viewPager = (ViewPager) findViewById(R.id.view_pager);
    ImagePagerAdapter adapter = new ImagePagerAdapter();
    viewPager.setAdapter(adapter);
    viewPager.setCurrentItem(position);

这是一个简单的答案，而不是这段代码：

ImagePagerAdapter adapter = new ImagePagerAdapter(mContext , icons[position]);

这很有效。

viewPager.setCurrentItem(position);

现在下面是我的整个应用代码：

MainActivity.java

package com.td.gridview;

import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.ViewGroup.LayoutParams;
import android.view.ViewTreeObserver;
import android.widget.AdapterView;
import android.widget.BaseAdapter;
import android.widget.GridView;
import android.widget.ImageView;
import android.widget.RelativeLayout;
import android.widget.TextView;
import android.widget.AdapterView.OnItemClickListener;

public class MainActivity extends Activity {


    private GridView photoGrid;
    private int mPhotoSize, mPhotoSpacing;
    private ImageAdapter imageAdapter;

    // Some items to add to the GRID
    private static final String[] CONTENT = new String[] 
            { 
            "Akon", "Justin Bieber", "AlRight", "Big Sean",
            "Britney Spears", "Hilary", "Micheal Buble", "Akon", "Justin Bieber", "AlRight", "Big Sean",
            "Britney Spears", "Hilary", "Micheal Buble", "Britney Spears", "Hilary", "Micheal Buble", "Akon",
            "Justin Bieber", "AlRight", "Big Sean", "Britney Spears", "Hilary", "Micheal Buble", "Akon",
            "Justin Bieber", "AlRight", "Big Sean", "Britney Spears", "Hilary", "Micheal Buble", "Akon",
            "Justin Bieber", "AlRight", "Big Sean", "Britney Spears", "Hilary", "Micheal Buble", "Britney Spears",
            "Hilary", "Micheal Buble", "Akon", "Justin Bieber", "AlRight", "Big Sean", "Britney Spears", "Hilary",
            "Micheal Buble" 
            };
    static final int[] ICONS = new int[] 
            { 
            R.drawable.cover_akon, R.drawable.cover_justin,
            R.drawable.cover_alright, R.drawable.cover_big_sean, R.drawable.cover_britney, R.drawable.cover_hilary,
            R.drawable.cover_mb, R.drawable.cover_akon, R.drawable.cover_justin, R.drawable.cover_alright,
            R.drawable.cover_big_sean, R.drawable.cover_britney, R.drawable.cover_hilary, R.drawable.cover_mb,
            R.drawable.cover_britney, R.drawable.cover_hilary, R.drawable.cover_mb, R.drawable.cover_akon,
            R.drawable.cover_justin, R.drawable.cover_alright, R.drawable.cover_big_sean, R.drawable.cover_britney,
            R.drawable.cover_hilary, R.drawable.cover_mb, R.drawable.cover_akon, R.drawable.cover_justin,
            R.drawable.cover_alright, R.drawable.cover_big_sean, R.drawable.cover_britney, R.drawable.cover_hilary,
            R.drawable.cover_mb, R.drawable.cover_akon, R.drawable.cover_justin, R.drawable.cover_alright,
            R.drawable.cover_big_sean, R.drawable.cover_britney, R.drawable.cover_hilary, R.drawable.cover_mb,
            R.drawable.cover_britney, R.drawable.cover_hilary, R.drawable.cover_mb, R.drawable.cover_akon,
            R.drawable.cover_justin, R.drawable.cover_alright, R.drawable.cover_big_sean, R.drawable.cover_britney,
            R.drawable.cover_hilary, R.drawable.cover_mb 
            };

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



        // get the photo size and spacing
        mPhotoSize = getResources().getDimensionPixelSize(R.dimen.photo_size);
        mPhotoSpacing = getResources().getDimensionPixelSize(R.dimen.photo_spacing);

        // initialize image adapter
        imageAdapter = new ImageAdapter();

        photoGrid = (GridView) findViewById(R.id.albumGrid);

        //start sent image to full screen             

        /**
         * On Click event for Single Gridview Item
         * */
        photoGrid.setOnItemClickListener(new OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View v,
                    int position, long id) {

                // Sending image id to FullScreenActivity
                Intent i = new Intent(getApplicationContext(), SwipeActivity.class);
                // passing array index
                i.putExtra("id", position);
                startActivity(i);
            }
        });
        //end sent image to full screen

        // set image adapter to the GridView
        photoGrid.setAdapter(imageAdapter);

        // get the view tree observer of the grid and set the height and numcols dynamically
        photoGrid.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
            @Override
            public void onGlobalLayout() {
                if (imageAdapter.getNumColumns() == 0) {
                    final int numColumns = (int) Math.floor(photoGrid.getWidth() / (mPhotoSize + mPhotoSpacing));
                    if (numColumns > 0) {
                        final int columnWidth = (photoGrid.getWidth() / numColumns) - mPhotoSpacing;
                        imageAdapter.setNumColumns(numColumns);
                        imageAdapter.setItemHeight(columnWidth);

                    }
                }
            }
        });
    }

    // ///////// ImageAdapter class /////////////////
    public class ImageAdapter extends BaseAdapter {
        private LayoutInflater mInflater;
        private int mItemHeight = 0;
        private int mNumColumns = 0;
        private RelativeLayout.LayoutParams mImageViewLayoutParams;

        public ImageAdapter() {
            mInflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            mImageViewLayoutParams = new RelativeLayout.LayoutParams(LayoutParams.MATCH_PARENT,
                    LayoutParams.MATCH_PARENT);
        }

        public int getCount() {
            return CONTENT.length;
        }

        // set numcols
        public void setNumColumns(int numColumns) {
            mNumColumns = numColumns;
        }

        public int getNumColumns() {
            return mNumColumns;
        }

        // set photo item height
        public void setItemHeight(int height) {
            if (height == mItemHeight) {
                return;
            }
            mItemHeight = height;
            mImageViewLayoutParams = new RelativeLayout.LayoutParams(LayoutParams.MATCH_PARENT, mItemHeight);
            notifyDataSetChanged();
        }

        public Object getItem(int position) {
            return position;
        }

        public long getItemId(int position) {
            return position;
        }

        public View getView(final int position, View view, ViewGroup parent) {

            if (view == null)
                view = mInflater.inflate(R.layout.photo_item, null);

            ImageView cover = (ImageView) view.findViewById(R.id.cover);
            TextView title = (TextView) view.findViewById(R.id.title);

            cover.setLayoutParams(mImageViewLayoutParams);

            // Check the height matches our calculated column width
            if (cover.getLayoutParams().height != mItemHeight) {
                cover.setLayoutParams(mImageViewLayoutParams);
            }

            cover.setImageResource(ICONS[position % ICONS.length]);
            title.setText(CONTENT[position % CONTENT.length]);

            return view;
        }
    }

}

SwipeActivity.java

    package com.td.gridview;

    import android.app.Activity;
    import android.content.Context;
    import android.content.Intent;
    import android.os.Bundle;
    import android.support.v4.view.PagerAdapter;
    import android.support.v4.view.ViewPager;
    import android.view.View;
    import android.view.ViewGroup;
    import android.widget.ImageView;



    public class SwipeActivity extends Activity 
    {   

      @Override
      public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.swipe_view);

     // get intent data
        Intent i = getIntent();

        // Selected image id
        int position = i.getExtras().getInt("id");

    ViewPager viewPager = (ViewPager) findViewById(R.id.view_pager);
    ImagePagerAdapter adapter = new ImagePagerAdapter();
    viewPager.setAdapter(adapter);
    viewPager.setCurrentItem(position);
  }

  private class ImagePagerAdapter extends PagerAdapter 
  {
      int[] icons = MainActivity.ICONS;    

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

    @Override
    public boolean isViewFromObject(View view, Object object) 
    {
      return view == ((ImageView) object);
    }

    @Override
    public Object instantiateItem(ViewGroup container, int position) 
    {
      Context context = SwipeActivity.this;
      ImageView imageView = new ImageView(context);
//      int padding = context.getResources().getDimensionPixelSize(
//          R.dimen.padding_large);
//      imageView.setPadding(padding, padding, padding, padding);
      imageView.setScaleType(ImageView.ScaleType.CENTER_INSIDE);
      imageView.setImageResource(icons[position]);
      ((ViewPager) container).addView(imageView, 0);
      return imageView;
    }

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

activity_main.xml中

<GridView xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/albumGrid"
    style="@style/PhotoGrid"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:background="@color/black"
    android:columnWidth="@dimen/photo_size"
    android:horizontalSpacing="@dimen/photo_spacing"
    android:numColumns="auto_fit"
    android:padding="4dp"
    android:scrollbars="none"
    android:stretchMode="columnWidth"
    android:verticalSpacing="@dimen/photo_spacing" />

photo_item.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/album_item"
android:layout_width="match_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >

<ImageView
    android:id="@+id/cover"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_alignBottom="@+id/cover"
    android:background="#70000000"
    android:padding="6dp" >

    <TextView
        android:id="@+id/title"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:ellipsize="end"
        android:singleLine="true"
        android:textColor="@color/white"
        android:textSize="12sp"
        android:textStyle="bold" />
</LinearLayout>
</RelativeLayout>

swipe_view.xml

<android.support.v4.view.ViewPager xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/view_pager"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" />

Answer 1

已发布here

顾名思义，它是应用程序/对象当前状态的上下文。它允许新创建的对象了解正在发生的事情。通常，您可以调用它来获取有关程序其他部分（活动，包/应用程序）的信息

错误在于您尝试将除上下文之外的类传递给参数您应尝试将SwipeActivity替换为SwipeActivity.this或getApplicationContext()。

Answer 2

你有一个GridView，你点击一个图像，你看到一个swipeView内的图像，为了继续查看其余的图像而不回去，我是对吗？

假设你的SwipeActivity做了它必须做的事情（使用＆＃34; id＆＃34;你传递的字符串在正确的图像中开始），如果你需要一个Context传递给适配器，只需创建一个字段你的活动名为mContext，并给它活动＆＃34;这个＆＃34;输入onCreate方法时的值;

class MyActivity extends Activity ...{

Context mContext;

...

@Override
onCreate(Bundle savedInstanceState){


mContext = this;

...

ImagePagerAdapter adapter = new ImagePagerAdapter(mContext , icons[position]);

}
}

另一方面，如果你只是想一次只看一个图像，然后再使用PageAdapter再次返回，那将不是最佳选择，因为它的目的是在分页结构中查看图像条带相反，你可以使用某种simnple imageView容器来做到这一点。

来自我的评论：

then use the setCurrentItem(position) to get there

如何将类发送或传递给上下文变量？

2 个答案: