Question

我编写了此代码，用于使用picasso从服务器下载图像。以下是ImageAdapter.java：

import com.squareup.picasso.Picasso;
import android.content.Context;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.GridView;
import android.widget.ImageView;

public class ImageAdapter extends BaseAdapter {
    private Context mContext;
    int imageTotal = 7;
    public static String[] mThumbIds = {
            "http://imageshack.com/a/img923/2796/PB1lxo.jpg"
    };

    public ImageAdapter(Context c) {
        mContext = c;
    }

    public int getCount() {
        return imageTotal;
    }

    @Override
    public String getItem(int position) {
        return mThumbIds[position];
    }

    public long getItemId(int position) {
        return 0;
    }

    public View getView(int position, View convertView, ViewGroup parent) {
        ImageView imageView;
        if (convertView == null) {
            imageView = new ImageView(mContext);
            imageView.setLayoutParams(new GridView.LayoutParams(480, 480));
            imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
            imageView.setPadding(8, 8, 8, 8);
        } else {
            imageView = (ImageView) convertView;
        }
        String url = getItem(position);
        Picasso.with(mContext)
                .load(url)
                .placeholder(R.drawable.loader)
                .fit()
                .centerCrop().into(imageView);
        return imageView;
    }
}

这里是名为ThirdActivity的主要活动：

import android.app.Activity;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.GridView;

public class ThirdActivity extends Activity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        this.setContentView(R.layout.gridview_layout);
        final GridView gridview = (GridView) findViewById(R.id.gridview);
        gridview.setAdapter(new ImageAdapter(this));
        gridview.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            public void onItemClick(AdapterView<?> parent, View v, int position, long id) {
                Intent i = new Intent(getApplicationContext(), FullImageActivity.class);
                i.putExtra("id", position);
                startActivity(i);
            }
        });
    }
}

这是FullImageActivity.java（它显示用户全屏点击的图像）：

import android.app.Activity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.AsyncTask;
import android.os.Bundle;
import android.widget.ImageView;
import java.io.InputStream;

public class FullImageActivity extends Activity {

    ProgressDialog pDialog;
    ImageView img;
    Bitmap bitmap;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.fullimageviewer);

        Intent i = getIntent();
        int position = i.getExtras().getInt("id");
        ImageAdapter imageAdapter = new ImageAdapter(this);

        img = (ImageView) findViewById(R.id.image);
        String url = imageAdapter.getItem(position);

        new DownloadImage().execute(url);
    }
    private class DownloadImage extends AsyncTask<String, Void, Bitmap> {

        @Override
        protected Bitmap doInBackground(String... URL) {
            String imageURL = URL[0];
            Bitmap bitmap = null;
            try {
                InputStream input = new java.net.URL(imageURL).openStream();
                bitmap = BitmapFactory.decodeStream(input);
            } catch (Exception e) {
                e.printStackTrace();
            }
            return bitmap;
        }

        @Override
        protected void onPostExecute(Bitmap result) {
            img.setImageBitmap(result);
        }
    }
 }

这是logcat我get.everytime我尝试打开此活动应用程序崩溃。我是非常新的，我似乎无法理解该怎么做。感谢任何帮助.Logcat：

E/AndroidRuntime: FATAL EXCEPTION: main Process: com.wildersdevelopment.insoletoprototype, PID: 3244
java.lang.ArrayIndexOutOfBoundsException: length=1; index=1
    at com.wildersdevelopment.insoletoprototype.ImageAdapter.getItem(ImageAdapter.java:31)
    at com.wildersdevelopment.insoletoprototype.ImageAdapter.getView(ImageAdapter.java:48)
    at android.widget.AbsListView.obtainView(AbsListView.java:2346)
    at android.widget.GridView.makeAndAddView(GridView.java:1439)
    at android.widget.GridView.makeRow(GridView.java:366)
    at android.widget.GridView.fillDown(GridView.java:307)
    at android.widget.GridView.fillFromTop(GridView.java:442)
    at android.widget.GridView.layoutChildren(GridView.java:1282)
    at android.widget.AbsListView.onLayout(AbsListView.java:2148)
    at android.view.View.layout(View.java:16630)
    at android.view.ViewGroup.layout(ViewGroup.java:5437)
    at android.widget.FrameLayout.layoutChildren(FrameLayout.java:336)
    at android.widget.FrameLayout.onLayout(FrameLayout.java:273)
    at android.view.View.layout(View.java:16630)
    at android.view.ViewGroup.layout(ViewGroup.java:5437)
    at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1743)
    at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1586)
    at android.widget.LinearLayout.onLayout(LinearLayout.java:1495)
    at android.view.View.layout(View.java:16630)
    at android.view.ViewGroup.layout(ViewGroup.java:5437)
    at android.widget.FrameLayout.layoutChildren(FrameLayout.java:336)
    at android.widget.FrameLayout.onLayout(FrameLayout.java:273)
    at com.android.internal.policy.PhoneWindow$DecorView.onLayout(PhoneWindow.java:2678)
    at android.view.View.layout(View.java:16630)
    at android.view.ViewGroup.layout(ViewGroup.java:5437)
    at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:2171)
    at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1931)
    at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1107)
    at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6013)
    at android.view.Choreographer$CallbackRecord.run(Choreographer.java:858)
    at android.view.Choreographer.doCallbacks(Choreographer.java:670)
    at android.view.Choreographer.doFrame(Choreographer.java:606)
    at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:844)
    at android.os.Handler.handleCallback(Handler.java:739)
    at android.os.Handler.dispatchMessage(Handler.java:95)
    at android.os.Looper.loop(Looper.java:148)
    at android.app.ActivityThread.main(ActivityThread.java:5417)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)

Answer 1

您在阵列中只声明了一个图像：

public static String[] mThumbIds = {
        "http://imageshack.com/a/img923/2796/PB1lxo.jpg"
};

但你提到你的总图像数为7：

int imageTotal = 7;

当它在getItem中尝试获取第二个元素（index = 1）时，它会给出异常，因为数组中不存在索引。

设置imageTotal = 1或在String数组中定义7个字符串。

或者，您可以将getCount更改为：

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

我一直得到E / AndroidRuntime：致命的例外：主要

1 个答案: