Question

我有一个列表，我想在列表中的每一行的单选按钮上给出点击事件。但是这段代码不起作用。强行关闭。请允许我帮忙。我是新手。

 package com.example.radiogroup;


    import java.util.ArrayList;
    import java.util.HashMap;

    import android.support.v7.app.ActionBarActivity;
    import android.support.v7.app.ActionBar;
    import android.support.v4.app.Fragment;
    import android.app.Activity;
    import android.content.Context;
    import android.database.DataSetObserver;
    import android.os.Bundle;
    import android.view.LayoutInflater;
    import android.view.Menu;
    import android.view.MenuItem;
    import android.view.View;
    import android.view.View.OnClickListener;
    import android.view.ViewGroup;
    import android.widget.AdapterView;
    import android.widget.AdapterView.OnItemClickListener;
    import android.widget.BaseAdapter;
    import android.widget.Checkable;
    import android.widget.ImageView;
    import android.widget.ListAdapter;
    import android.widget.ListView;
    import android.widget.RadioButton;
    import android.widget.TextView;
    import android.widget.Toast;
    import android.os.Build;

    public class MainActivity extends Activity implements Checkable
{

    private ArrayList<HashMap<String,Object>> data;
    private ListAdapter adapter;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        ListView lv=(ListView)findViewById(R.id.listView1);
        lv.setChoiceMode(ListView.CHOICE_MODE_SINGLE);
        data=new ArrayList<HashMap<String, Object>>();
        prepareListData();
        adapter = new ListAdapter(this,data);
        lv.setAdapter(adapter);

    /*  lv.setOnItemClickListener(new OnItemClickListener()
        {

            @Override
            public void onItemClick(AdapterView<?> parent, View view,
                    int position, long id)
            {

            {
                if(position==0)
                {
                    Toast.makeText(getApplicationContext(), "Move forward", 
      Toast.LENGTH_SHORT).show();
                }


            }
            }

        }); */





    }
    private void prepareListData()
    {
        HashMap<String,Object> row1=new HashMap<String,Object>();
        row1.put("ID",1 );
        row1.put("NAME","Taj Mahal");
        data.add(row1);

        HashMap<String,Object> row2=new HashMap<String,Object>();
        row2.put("ID",2 );
        row2.put("NAME","Agra Fort");
        data.add(row2);

        HashMap<String,Object> row3=new HashMap<String,Object>();
        row3.put("ID",3 );
        row3.put("NAME","Ram Baugh");
        data.add(row3);

        HashMap<String,Object> row4=new HashMap<String,Object>();
        row4.put("ID",4 );
        row4.put("NAME","Panch Mahal");
        data.add(row4);

        HashMap<String,Object> row5=new HashMap<String,Object>();
        row5.put("ID",5 );
        row5.put("NAME","Musamman Burj");
        data.add(row5);

    }
    class ListAdapter extends BaseAdapter
    {
        private Context context;
        private ArrayList<HashMap<String,Object>> list;
         ViewHolder holder;



         public ListAdapter(Context context,ArrayList<HashMap<String,Object>> list){
                this.context = context;
                this.list = list;
                holder.rb.setOnClickListener(new OnClickListener() {

                    @Override
                    public void onClick(View v) 
                    {
                        Toast.makeText(getApplicationContext(), "Move forward", Toast.LENGTH_SHORT).show();

                    }
                });
         }


        @Override
        public int getCount() {
            // TODO Auto-generated method stub
            return list.size();
        }

        @Override
        public Object getItem(int position) {
            // TODO Auto-generated method stub
            return list.get(position);
        }

        @Override
        public long getItemId(int position) {
            // TODO Auto-generated method stub
            return position;
        }


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

                if(convertView == null){
                    holder = new ViewHolder();
                    convertView = LayoutInflater.from(context).inflate(R.layout.row,null,false);
                    holder.rb = (RadioButton) convertView.findViewById(R.id.radioButton1);

                    convertView.setTag(holder);
                }else{
                    holder = (ViewHolder) convertView.getTag();
                }

                holder.rb.setText(list.get(position).get("NAME").toString());

            return convertView;
        }
         class ViewHolder
            {
                RadioButton rb;
            }

    }
    @Override
    public void setChecked(boolean checked) {
        // TODO Auto-generated method stub

    }
    @Override
    public boolean isChecked() {
        // TODO Auto-generated method stub
        return false;
    }
    @Override
    public void toggle() {
        // TODO Auto-generated method stub

    }




}

Answer 1

在适配器中的getview方法中使用它

 holder.rb.setOnClickListener(new OnClickListener()
{

            @Override
            public void onClick(View v) 
            {
                Toast.makeText(getApplicationContext(), "Move forward",        Toast.LENGTH_SHORT).show();

            }
        });

在OnCreate Methed上使用它

 lv.setOnItemClickListener(new OnItemClickListener()
{

    @Override
    public void onItemClick(AdapterView<?> parent, View view,
            int position, long id)
    {

    {
        if(position==0)
        {
            Toast.makeText(getApplicationContext(), "Move forward "+position, Toast.LENGTH_SHORT).show();
        }
  else
   if(position==1)
        {
            Toast.makeText(getApplicationContext(), "Move forward "+position,  
       Toast.LENGTH_SHORT).show();
        }


    }
    }

});

Answer 2

在 ListAdapter 类的构造函数中，您尚未初始化ViewHolder对象，因此您无法访问该类的成员。删除

 holder.rb.setOnClickListener(new OnClickListener() {

                @Override
                public void onClick(View v) 
                {
                    Toast.makeText(getApplicationContext(), "Move forward", Toast.LENGTH_SHORT).show();

                }
            });

来自 ListAdapter 构造函数，并在类和成员初始化之后将其放在 getView（）中。

后

 if(convertView == null){
                holder = new ViewHolder();
                convertView = LayoutInflater.from(context).inflate(R.layout.row,null,false);
                holder.rb = (RadioButton) convertView.findViewById(R.id.radioButton1);

                convertView.setTag(holder);
            }else{
                holder = (ViewHolder) convertView.getTag();
            }

在getView方法中

。

单选按钮上的onclick事件按钮不起作用

2 个答案: