1.layout_main里添加listView

2.新建item_layout

image.png

3.新建类，属性为item_layout每一个控件中要装入的数据

package com.example.baseadapter;

public class Msg {
    private int img;
    private String name;
    private String text;
    boolean isLike;
//getter，setter,和构造方法自行添加

4.新建自定义myAdapter 继承自BaseAdapter

public class myAdapter extends BaseAdapter {
    private List<Msg> list;
    Context context;
    ViewHold viewHold;

    public myAdapter(List<Msg> list, Context context) {
        this.list = list;
        this.context = context;
    }

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

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

       //获取布局
 view=LayoutInflater.from(context).inflate(R.layout.list_item,null);

//对布局中的控件添加数据项对应的数据
        ImageView imageView = view.findViewById(R.id.img);
        imageView.setImageResource(list.get(position).getImg());

        TextView name = view.findViewById(R.id.name);
        name.setText(list.get(position).getName());

        TextView text = view.findViewById(R.id.text);
        text.setText(list.get(position).getText());

        final ImageView islike = view.findViewById(R.id.like);
        if (list.get(position).isLike) {
            islike.setImageResource(R.mipmap.liked);
        } else {
            islike.setImageResource(R.mipmap.like);
        }

//对控件添加对应的响应事件
        ImageView repose = view.findViewById(R.id.repost);
        repose.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Toast.makeText(context, "++++++++++啦啦啦+++++++++", Toast.LENGTH_LONG).show();
            }
        });

        islike.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                boolean temp = list.get(position).isLike;
                temp = !temp;
                if (temp) {
                    islike.setImageResource(R.mipmap.liked);
                } else {
                    islike.setImageResource(R.mipmap.like);
                }
                list.get(position).isLike = temp;
                myAdapter.this.notifyDataSetChanged();

            }
        });


        return view;
    }
}

5.在mainactivity 中添加数据，并将新建适配器，为listview 装入数据

 private ListView listView;
    private ImageView write;
    private List<Msg> list;
//添加数据项
  private void initData() {
       for(int i = 0;i < 8;i++){
           Msg msg=new Msg(imgs[i],"用户"+(i+1),"下雨了，好冷啊，冻死了"+(i+1),
                i%3==0?true:false);
           list.add(msg);
       }
    }
//装入数据
 @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        listView = findViewById(R.id.list);
        write = findViewById(R.id.write);
        list=new ArrayList<>();

        initData();
        final myAdapter myAdapter=new myAdapter(list,this);

        listView.setAdapter(myAdapter);

6.添加新的item

 write.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Msg m=new Msg(R.mipmap.profile9,"新用户","新动态",false);
                list.add(m);
                myAdapter.notifyDataSetChanged();
                listView.setTranscriptMode(AbsListView.TRANSCRIPT_MODE_ALWAYS_SCROLL);
            }
        });

7.对Adapter进行优化
在自定义的Adatper类中添加静态类,属性为要找到控件

static class ViewHold{
        ImageView imageView,repose,islike;
        TextView text,name;
    }

在自定义Adapter类 getView()方法中添加

if(view==null) {
            view = LayoutInflater.from(context).inflate(R.layout.list_item, null);
            viewHold=new ViewHold();
            viewHold.imageView = view.findViewById(R.id.img);
            viewHold.name = view.findViewById(R.id.name);
            viewHold.text = view.findViewById(R.id.text);
            viewHold.islike = view.findViewById(R.id.like);
            viewHold.repose = view.findViewById(R.id.repost);
            view.setTag(viewHold);
        }else {
            viewHold=(ViewHold)view.getTag();
        }

之前所有的findViewById都可以用viewHold成员变量代替。