Question

我有一个listview，因为我正在使用BaseAdapter。我希望listitem的值在Activity中。以下是我的代码

MainActivity.java

ArrayList<String> dkulist = new ArrayList<>();
CustomAdapter adapter;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main_layout);
    userList = (ListView) findViewById(R.id.userList);
    userList.setAdapter(adapter);
}

CustomAdapter.java

public class CustomAdapter extends BaseAdapter {
    @Override
    public View getView(int position, View convertView,final ViewGroup  parent) {
        if (convertView == null) {
          LayoutInflater inflater = LayoutInflater.from(parent.getContext());
          convertView = inflater.inflate(R.layout.listitem, parent, false);
    }        

    TextView Name = (TextView) convertView.findViewById(R.id.name);

    Name.setText("Dummy name");
    final boolean click_flag = false;
    convertView.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
          if(click_flag) {
             view.setBackgroundColor(Color.BLUE); // this is also not working
             // How to get this name value in my MainActivity.java
          } else {
             view.setBackgroundColor(Color.TRANSPARENT);
          }
        }
}

感谢Adv

Answer 1

使用Interface将值传递给Activity

public interface OnItemClickListener {
    void onItemClick (Object value);
}

在Activity中实现上述侦听器，并将其实例传递给适配器

private final OnItemClickListener mListener;

convertView.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View view) {
         view.setBackgroundColor(Color.BLUE); // this will work now
         // This is how to get this name value in my MainActivity.java
         mListener.onItemClick(value);
    }

Answer 2

您需要初始化Adapter的实例并设置为userlist，而不是仅传递未分配的适配器变量。

Answer 3

活动代码：

public class MainActivity implements CustomAdapter. OnItemClickListener

ArrayList<String> dkulist = new ArrayList<>();
CustomAdapter adapter;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main_layout);
    userList = (ListView) findViewById(R.id.userList);
    userList.setAdapter(adapter);
}

@override
public void onItemClick (Object value){
// do your stuff here
}
}

适配器代码：

public class CustomAdapter extends BaseAdapter {

private final OnItemClickListener mListener;

   public CustomAdapter(Context context){
    // this will register the listener with MainActivity.java
    mListener = (OnItemClickListener) context
   }
    @Override
    public View getView(int position, View convertView,final ViewGroup  parent) {
        if (convertView == null) {
          LayoutInflater inflater = LayoutInflater.from(parent.getContext());
          convertView = inflater.inflate(R.layout.listitem, parent, false);
    }        

    TextView Name = (TextView) convertView.findViewById(R.id.name);

    Name.setText("Dummy name");
    final boolean click_flag = false;
    convertView.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
          if(click_flag) {
             view.setBackgroundColor(Color.BLUE); // this is also not working
             // How to get this name value in my MainActivity.java
             // Add below code to delegate the value to activity
             mListener.onItemClick(value);
          } else {
             view.setBackgroundColor(Color.TRANSPARENT);
          }
        }

public interface OnItemClickListener {
    void onItemClick (Object value);
}
}

Answer 4

试试这个

在您的MainAcitivity.java中，

userList.setOnItemClickListener(new ListItemClickListener());

private class ListItemClickListenerimplements ListView.OnItemClickListener {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position,
                                long id) {
            String text = ((TextView) view.findViewById(R.id.name)).getText().toString();
        }

    }

从getAdapter获取活动的价值

4 个答案: