Custom Implementation of Android BaseAdapter (Universal Adapter III)

In the last article, we said that if there are many controls in setData, we still need to write a lot of code in this method. In order to reduce the convenience of development, this time we will optimize it again on this basis. The implementation principle is this, every time in setData to find the control, and then setXXX () or something, we can put this write implementation as in ViewHolder, in ViewHolder to write a chain method to help us to achieve the function (I will not repeat the code about ViewHodler class, the code here: Android custom implementation BaseAdapter (universal adapter 1)), chain method as follows:

public ViewHolder setText(int viewId, String data){
  TextView tv = getView(viewId);
  tv.setText(data);
  return this;
 }

Through this method, we can very good to set the corresponding content, only need to pass a need to set the control id, and then pass the corresponding data, you can achieve the effect of setting text, the following look at our MyAdapter. java in the code

MyAdapter.java

/**
*  Upper 1 In an article MyAdapter
*/
public class MyAdapter extends MyBaseAdapter {
 public MyAdapter(List<Student> data) {
  super(data);
 }
 @Override
 public void setData(ViewHolder holder, Student t) {
  TextView tvName = holder.getView(R.id.mTv1);
  tvName.setText(t.getName());
  TextView tvSex = holder.getView(R.id.mTv2);
  tvSex.setText(t.getSex());
 }
}

/**
*  Optimized MyAdapter
*/
public class MyAdapter extends MyBaseAdapter {
 public MyAdapter(List<Student> data) {
  super(data);
 }
 @Override
 public void setData(ViewHolder holder, Student t) {
  holder.setText(R.id.mTv1, t.getName()).setText(R.id.mTv2, t.getSex());
 }
}

ok, compared with the implementation of setData under 1, we can replace the above implementation with only one code here. Is this more convenient? In this way, our expansion is more convenient. If we say that we not only set the text content, but set the picture through the picture control? Quite simply, we just need to add the method we want to implement in ViewHolder, such as setting the picture. We can add the following code:

public ViewHolder setImageResource(int viewId,int resId){
  ImageView img = getView(viewId);
  img.setImageResource(resId);
  return this;
 }
 public ViewHolder setImageBitmap(int viewId, Bitmap bm){
  ImageView img = getView(viewId);
  img.setImageBitmap(bm);
  return this;
 }

After adding these two methods, it is very easy to set the picture, just pass the corresponding parameters in setData

@Override
 public void setData(ViewHolder holder, Student t) {
  holder.setText(R.id.mTv1, t.getName()).setText(R.id.mTv2, t.getSex());
  holder.setImageResource(R.id.img1, Resources id).setImageBitmap(R.id.img2,bm);
 }

Ok, a general adapter has been completed, the overall framework and code have been achieved, I will all the code under the synthesis of 1, written below, convenient for everyone to use, respectively is MainActivity. java (main interface class, responsible for passing parameters to set the data of ListView), MyAdapter. java (custom adapter), MyBaseAdapter. java (general adapter class), ViewHolder. java (general holding class object), and entity class ES40java

MainActivity.java

public class MainActivity extends AppCompatActivity{

 private List<Student> data;
 private ListView mList;
 MyAdapter adapter;
 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  getData();
  mList = (ListView) findViewById(R.id.mList);
  adapter = new MyAdapter(data);
  mList.setAdapter(adapter);
 }

 private void getData() {
  data = new ArrayList<>();
  Student stu = null;
  for (int i = 0; i < 20; i++) {
   stu = new Student();
   stu.setName(" Name " + i);
   stu.setSex(i % 2 == 0 ? " Male " : " Female ");
   data.add(stu);
  }
 }

}

MyAdapter.java

public class MyAdapter extends MyBaseAdapter<Student> {

 public MyAdapter(List<Student> data) {
  super(data);
 }

 @Override
 public void setData(ViewHolder holder, Student t) {
  holder.setText(R.id.mTv1, t.getName()).setText(R.id.mTv2, t.getSex());

 }

}

MyBaseAdapter.java

public abstract class MyBaseAdapter<T> extends BaseAdapter {
 protected List<T> data;
 public MyBaseAdapter(List<T> data){
  this.data = data;
 }
 @Override
 public int getCount() {
  return data == null ? 0 : data.size();
 }

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

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

 @Override
 public View getView(int position, View convertView, ViewGroup parent) {
  ViewHolder holder = ViewHolder.getHolder(convertView,parent,position, R.layout.list_item);
  setData(holder,data.get(position));
  return holder.getConvertView();
 }
 public abstract void setData(ViewHolder holder,T t);
}

ViewHolder.java

public class ViewHolder {
 private int position;
 private SparseArray<View> array;
 private View convertView;
 private Context context;

 private ViewHolder(ViewGroup parent, int position, int layout) {
  this.position = position;
  this.context = parent.getContext();
  convertView = LayoutInflater.from(parent.getContext()).inflate(layout, null);
  convertView.setTag(this);
  array = new SparseArray<>();
 }

 public static ViewHolder getHolder(View convertView, ViewGroup parent, int position, int layout) {
  if (convertView == null) {
   return new ViewHolder(parent, position, layout);
  } else {
   ViewHolder holder = (ViewHolder) convertView.getTag();
   holder.position = position;
   return holder;
  }
 }

 public <T extends View> T getView(int viewId) {
  View view = array.get(viewId);
  if (view == null) {
   view = convertView.findViewById(viewId);
   array.put(viewId, view);
  }
  return (T) view;
 }

 public View getConvertView() {
  return convertView;
 }

 public ViewHolder setText(int viewId, String data) {
  TextView tv = getView(viewId);
  tv.setText(data);
  return this;
 }

 public ViewHolder setImageResource(int viewId, int resId) {
  ImageView img = getView(viewId);
  img.setImageResource(resId);
  return this;
 }

 public ViewHolder setImageBitmap(int viewId, Bitmap bm) {
  ImageView img = getView(viewId);
  img.setImageBitmap(bm);
  return this;
 }
}

Student.java

public class Student {
 private String name;
 private String sex;
 public String getName() {
  return name;
 }
 public void setName(String name) {
  this.name = name;
 }
 public String getSex() {
  return sex;
 }
 public void setSex(String sex) {
  this.sex = sex;
 }
}