android - Gridview教程问题

Question

我正在尝试进入 android 开发并且我正在学习教程，但是我真的被困在 HelloGridView 上了。教程，我周围都是 Apple 开发人员，所以没有任何 Android 经验的人可以问!

我尝试完成 HelloGridView 教程，但出现 17 个错误，但看不出哪里出错了？!？我有一种感觉，我错过了图书馆之类的东西？!？

由于我遇到了很多无法解决的错误，所以我截图了: http://users.cscs.wmin.ac.uk/~w1128683/help/Untitled.jpeg

问题在于 HelloGridView 和 ImageAdapter 类:

HelloGridView 类:

    package com.example.HelloGridView;

    import android.app.Activity;
    import android.os.Bundle;

    public class HelloGridView extends Activity {
        /** Called when the activity is first created. */
        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.main);

            GridView gridview = (GridView) findViewById(R.id.gridview);
            gridview.setAdapter(new ImageAdapter(this));

            gridview.setOnItemClickListener(new OnItemClickListener() {
                public void onItemClick(AdapterView<?> parent, View v, int position, long id) {
                    Toast.makeText(HelloGridView.this, "" + position, Toast.LENGTH_SHORT).show();
                }
            });
        }

ImageAdapter 类:

    package com.example.HelloGridView;

    public class ImageAdapter extends BaseAdapter {
        private Context mContext;

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

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

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

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

    // create a new ImageView for each item referenced by the Adapter
    public View getView(int position, View convertView, ViewGroup parent) {
        ImageView imageView;
        if (convertView == null) {  // if it's not recycled, initialize some attributes
            imageView = new ImageView(mContext);
            imageView.setLayoutParams(new GridView.LayoutParams(85, 85));
            imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
            imageView.setPadding(8, 8, 8, 8);
        } else {
            imageView = (ImageView) convertView;
        }

        imageView.setImageResource(mThumbIds[position]);
        return imageView;
    }

    // references to our images
    private Integer[] mThumbIds = {
            R.drawable.sample_2, R.drawable.sample_3,
            R.drawable.sample_4, R.drawable.sample_5,
            R.drawable.sample_6, R.drawable.sample_7,
            R.drawable.sample_0, R.drawable.sample_1,
            R.drawable.sample_2, R.drawable.sample_3,
            R.drawable.sample_4, R.drawable.sample_5,
            R.drawable.sample_6, R.drawable.sample_7,
            R.drawable.sample_0, R.drawable.sample_1,
            R.drawable.sample_2, R.drawable.sample_3,
            R.drawable.sample_4, R.drawable.sample_5,
            R.drawable.sample_6, R.drawable.sample_7
    };
    }

如果有人能告诉我哪里出了问题，或者至少能指出正确的方向，我们将不胜感激!

Answer 1

这是固定的设置，下次你需要为每个对象做导入:

你的 HelloGridView

package com.example.HelloGridView;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.GridView;
import android.widget.Toast;
import android.widget.AdapterView.OnItemClickListener;

public class HelloGridView extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        GridView gridview = (GridView) findViewById(R.id.gridview);
        gridview.setAdapter(new ImageAdapter(getApplicationContext()));

        gridview.setOnItemClickListener(new OnItemClickListener() {
            public void onItemClick(AdapterView<?> parent, View v,
                    int position, long id) {
                Toast.makeText(HelloGridView.this, "" + position,
                        Toast.LENGTH_SHORT).show();
            }
        });
    }
}

你的基础适配器

package com.example.HelloGridView;

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;

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

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

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

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

    // create a new ImageView for each item referenced by the Adapter
    public View getView(int position, View convertView, ViewGroup parent) {
        ImageView imageView;
        if (convertView == null) { // if it's not recycled, initialize some
                                    // attributes
            imageView = new ImageView(mContext);
            imageView.setLayoutParams(new GridView.LayoutParams(85, 85));
            imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
            imageView.setPadding(8, 8, 8, 8);
        } else {
            imageView = (ImageView) convertView;
        }

        imageView.setImageResource(mThumbIds[position]);
        return imageView;
    }

    // references to our images
    private Integer[] mThumbIds = { R.drawable.sample_2, R.drawable.sample_3, R.drawable.sample_4, R.drawable.sample_5, R.drawable.sample_6, R.drawable.sample_7, R.drawable.sample_0, R.drawable.sample_1, R.drawable.sample_2, R.drawable.sample_3, R.drawable.sample_4, R.drawable.sample_5, R.drawable.sample_6, R.drawable.sample_7, R.drawable.sample_0, R.drawable.sample_1, R.drawable.sample_2, R.drawable.sample_3, R.drawable.sample_4, R.drawable.sample_5, R.drawable.sample_6, R.drawable.sample_7 };
}