利用GridView實現單選效果

1.實現如圖所示的單選效果

由於Android提供的單選按鈕radiobutton只能單行或單列顯示，且樣式並不美觀，故可用GridView進行改造，實現單選效果，而要實現這樣的效果重點就在GridView的適配器這塊了。

首先是GridView的item的XML：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:orientation="vertical"
              android:layout_width="match_parent"
              android:layout_height="match_parent">
    <RelativeLayout
        android:id="@+id/options"
        android:layout_width="match_parent"
        android:layout_height="143dp">
        <ImageView
            android:id="@+id/imageView"
            android:layout_width="65dp"
            android:layout_height="65dp"/>
        <TextView
            android:id="@+id/textView"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_centerInParent="true"
            android:text="通訊錄"/>
    </RelativeLayout>

</LinearLayout>
裡邊很簡單，就只用來放顯示選中效果的imageView和文字的textView
接下來是適配器：

public class GridViewRadioAdapter extends BaseAdapter {
    private Context mContext;
    private int lastPosition = -1;            //記錄上一次選中的圖片位置，預設不選中
    private String[] str = null;              //放問題內容文字的數組

    public GridViewRadioAdapter(Context mContext) {
        this.mContext = mContext;
    }

    public void setStr(String[] str){      //在activity中調用此方法傳入問題的數組
        this.str = str;
    }

    public void setSelection(int position) {   //在activity中GridView的onItemClickListener中調用此方法，來設置選中位置
        lastPosition = position;
    }

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

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

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

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder viewHolder = null;
        if (convertView == null){
            viewHolder = new ViewHolder();
            convertView = LayoutInflater.from(mContext).inflate(R.layout.adapter_gridview_radio_item, null);
            viewHolder.textView = (TextView) convertView.findViewById(R.id.textView);
            viewHolder.imageView = (ImageView) convertView.findViewById(R.id.imageView);
            viewHolder.relativeLayout = (RelativeLayout) convertView.findViewById(R.id.options);
            convertView.setTag(viewHolder);
        }else {
            viewHolder = (ViewHolder) convertView.getTag();
        }
        viewHolder.textView.setText(str[position]);
        if (lastPosition == position){  //判斷是否為選中項，選中項與非選中項設置不同的樣式
            switch (position){     //選中狀態下設置樣式
                case 0:
                    viewHolder.imageView.setBackgroundResource(R.drawable.option_a_checked);
                    break;
                case 1:
                    viewHolder.imageView.setBackgroundResource(R.drawable.option_b_checked);
                    break;
                case 2:
                    viewHolder.imageView.setBackgroundResource(R.drawable.option_c_checked);
                    break;
                case 3:
                    viewHolder.imageView.setBackgroundResource(R.drawable.option_d_checked);
                    break;
            }
            viewHolder.relativeLayout.setBackgroundResource(R.drawable.shape_rect_orange);
        }else {      //非選中狀態下設置樣式
            switch (position){
                case 0:
                    viewHolder.imageView.setBackgroundResource(R.drawable.option_a);
                    break;
                case 1:
                    viewHolder.imageView.setBackgroundResource(R.drawable.option_b);
                    break;
                case 2:
                    viewHolder.imageView.setBackgroundResource(R.drawable.option_c);
                    break;
                case 3:
                    viewHolder.imageView.setBackgroundResource(R.drawable.option_d);
                    break;
            }
            viewHolder.relativeLayout.setBackgroundResource(R.drawable.shape_rect_gray);
        }
        return convertView;
    }

    class ViewHolder{
        private TextView textView;
        private ImageView imageView;
        private RelativeLayout relativeLayout;
    }
}

最後在activity中設置適配器：

GridViewRadioAdapter adapter = new GridViewRadioAdapter(mContext);
adapter.setStr(options);  //傳入問題的選項
mGridView.setAdapter(adapter);
mGridView.setOnItemClickListener(new AdapterView.OnItemClickListener() {

    @Override
    public void onItemClick(AdapterView<?> arg0, View arg1, int position, long arg3) {
        adapter.setSelection(position);  //傳值更新
        adapter.notifyDataSetChanged();  //每一次點擊通知adapter重新渲染
    }
});