ImageSwitcher的用法

遇到问题在GridView的定义放在使用之后，造成了空指针的异常

注意：ImageSwitcher的setFactory方法返回一个imageview对象，之后我们直接对switcher操作就行

Activity的代码如下

package com.phone.hty.myapplication;

import android.content.res.TypedArray;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.AdapterView;
import android.widget.GridView;
import android.widget.ImageSwitcher;
import android.widget.ViewSwitcher;

import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {

    private ImageSwitcher mImageSwitcher;
    private GridView mGridView;
    private LayoutInflater mLayoutInflater;


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

    private void initListener() {
        mGridView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                System.out.println("您点击了"+position);
                mImageSwitcher.setImageResource(R.drawable.avatars01);
            }
        });


    }

    private void initData() {
        TypedArray typedArray = getResources().obtainTypedArray(R.array.image);

        mImageSwitcher = (ImageSwitcher) findViewById(R.id.image_switcher);
        mGridView = (GridView) findViewById(R.id.gridView);
        mLayoutInflater = LayoutInflater.from(this);


        int[] images = new int[typedArray.length()];
        for (int i = 0;i<typedArray.length();i++){
            images[i] = typedArray.getResourceId(i,0);
        }

        ArrayList<Bean> list = new ArrayList<Bean>();
        for (int i = 0;i<typedArray.length();i++){
            Bean bean = new Bean("测试文本"+i,images[i]);
            list.add(bean);
        }
        mGridView.setAdapter(new MyAdapter(this,list));

        mImageSwitcher.setFactory(new ViewSwitcher.ViewFactory() {
            @Override
            public View makeView() {
                return mLayoutInflater.inflate(R.layout.image_view, null);
            }
        });
    }
}

Adapter的代码如下

package com.phone.hty.myapplication;

import android.content.Context;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;

import java.util.ArrayList;

/** * 作者：司马啸尘 * 创建日期：2016/3/26 * 描述： */
public class MyAdapter extends BaseAdapter {
    Context mContext;
    ArrayList<Bean> mList;

    public MyAdapter(Context context, ArrayList<Bean> list) {
        mContext = context;
        mList = list;
    }

    @Override
    public int getCount() {
        return mList.size();
    }

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

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

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        viewHolder holder;
        if (convertView == null) {
            convertView = View.inflate(mContext, R.layout.grid_view, null);
            holder = new viewHolder();
            holder.mImageView = (ImageView) convertView.findViewById(R.id.grid_image_view);
            holder.mTextView = (TextView) convertView.findViewById(R.id.grid_text_view);
            convertView.setTag(holder);
        } else {
            holder = (viewHolder) convertView.getTag();
        }
        holder.mTextView.setText(mList.get(position).getDesc());
        holder.mImageView.setImageResource(mList.get(position).getImage());

        return convertView;
    }
}

class viewHolder {
    public ImageView mImageView;
    public TextView mTextView;
}

总结：BaseAdapter的缓存使用还是不熟练，今天忘了
还有就是在java代码中把xml布局变成view对象是的用法

• 定义LayoutInflater对象
• 对他赋值 mLayoutInflater = LayoutInflater.from(this)传入上下文参数
• 对xml文件解析mLayoutInflater.inflate(R.layout.image_view, null)