Question

我有这段代码

public void onKillClick(View v) {
    TextView t = (TextView) v.findViewById(R.id.toptext);
    String s = t.getText().toString();
    net.killProcess(s);
}

row.xml中的按钮将onKillClick作为其收听者。

t.getText().toString()返回null。我不确定我是否添加了正确的onClickListener或者什么。

Client.java

package org.tsunamistudios.computerwatch;

import java.io.IOException;
import java.io.OptionalDataException;
import java.util.ArrayList;
import java.util.Collection;

import org.tsunamistudios.computerwatch.net.Net;
import org.tsunamistudios.computerwatch.processes.Program;

import android.app.ListActivity;
import android.content.Context;
import android.content.pm.ActivityInfo;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.TextView;

import com.tsunamistudios.computerwatch.R;

public class Client extends ListActivity {

    private static String message;
    private static ArrayList<Program> programs = new ArrayList<Program>();
    private static Net net = new Net();
    private static TextView txtView;
    private static ProgramAdapter prAdapter;
    private static Context context;
    private static ArrayList<TextView> textViews = new ArrayList<TextView>();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_client);
        setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
        context = getApplicationContext();          
    }

    private class GetObject extends AsyncTask<Void, Void, String> {

        @SuppressWarnings("unchecked")
        @Override
        protected String doInBackground(Void... arg0) {
            net.setSocket();
            try {
                getPrograms().addAll((Collection<? extends Program>) net.getObjectInputStream().readObject());
            } catch (OptionalDataException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (ClassNotFoundException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }           
            return null;
        }       

        protected void onPostExecute(String result) {
            prAdapter = new ProgramAdapter(context, R.layout.row, programs);
            setListAdapter(prAdapter);
        }
    }

    private class KillProcess extends AsyncTask<String, Void, Void> {
        @Override
        protected Void doInBackground(String... parems) {
            net.killProcess(parems[0]);
            return null;        
        }       
    }


    public void onKillClick(View v) {       
        String s = textViews.get(v.getId()).getText().toString();
        net.killProcess(s);
    }

    private class ProgramAdapter extends ArrayAdapter<Program> {

        private ArrayList<Program> programs;

        public ProgramAdapter(Context context, int textViewResourceId, ArrayList<Program> programs) {
            super(context, textViewResourceId, programs);
            this.programs = programs;
        }
        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            View v = convertView;
            if (v == null) {
                LayoutInflater vi = (LayoutInflater)getSystemService(Context.LAYOUT_INFLATER_SERVICE);
                v = vi.inflate(R.layout.row, null);
            }
            Program p = programs.get(position);
            if (p != null) {
                Bitmap bmp = BitmapFactory.decodeByteArray(p.getImage(), 0, p.getImage().length);
                TextView tt = (TextView) v.findViewById(R.id.toptext);
                TextView bt = (TextView) v.findViewById(R.id.bottomtext);
                ImageView im = (ImageView) v.findViewById(R.id.icon);
                im.setImageBitmap(bmp);

                if (tt != null) {
                      tt.setText("Name: "+ p.getName().substring(0, p.getName().length() - 4));  
                      textViews.add(tt);
                }
                if(bt != null) {
                      bt.setText("Desc: "+ p.getDescription());
                }
            }
            return v;
        }
    }

    public void onIpClick(View v){
        EditText et = (EditText) findViewById(android.R.id.empty);
        net.setHostName(et.getText().toString());
        new GetObject().execute((Void) null);
    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.client, menu);
        return true;
    }

    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        Client.message = message;
    }

    public static ArrayList<Program> getPrograms() {
        return programs;
    }

    public static void setTextView() {
        txtView.setText(getPrograms().get(0).getName() + getPrograms().get(0).getDescription());
    }

    public void setPrograms(ArrayList<Program> programs) {
        Client.programs = programs;
    }

    public Net getNet() {
        return net;
    }

    public void setNet(Net net) {
        Client.net = net;
    }


    public static TextView getTxtView() {
        return txtView;
    }
}

我的activity_main.xml

    <?xml version="1.0" encoding="utf-8"?>
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
       android:orientation="vertical"
       android:layout_width="fill_parent"
       android:layout_height="fill_parent"
       >
    <ListView
        android:id="@+id/android:list"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        />
    <TextView
        android:id="@+id/android:empty"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:text="@string/main_no_items"/>
    </LinearLayout>

row.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="?android:attr/listPreferredItemHeight"
    android:padding="6dip">
    <ImageView
        android:id="@+id/icon"
        android:layout_width="wrap_content"
        android:layout_height="fill_parent"
        android:layout_marginRight="6dip"
        android:src="@drawable/ic_launcher"
        />
    <LinearLayout
        android:orientation="vertical"
        android:layout_width="0dip"
        android:layout_weight="1"
        android:layout_height="fill_parent">
        <TextView
            android:id="@+id/toptext"
            android:layout_width="fill_parent"
            android:layout_height="0dip"
            android:layout_weight="1"
            android:gravity="center_vertical"
        />
        <TextView
            android:layout_width="fill_parent"
            android:layout_height="0dip"
            android:layout_weight="1" 
            android:id="@+id/bottomtext"
            android:singleLine="true"
            android:ellipsize="marquee"
        />
        <Button
        android:id="@+id/button1"
        android:layout_height = "wrap_content"
        android:layout_width ="wrap_content"
        android:text = "Enter"
        android:onClick = "onKillClick"
        android:gravity="right"
        />
    </LinearLayout>
</LinearLayout>

Answer 1

尝试在导致button1.setOnClickListner(listner)的{{1}}内添加Adapter。你会得到这样的东西：

row.xml

Answer 2

TextView t = (TextView) v.findViewById(R.id.toptext);

在getView（适配器）或onCreate（活动）中声明此行。在onKillClick函数内部，v是此控件（按钮），不包含顶部文本Textview。

Answer 3

尝试以下方法（使用膨胀视图）

public void onKillClick(View v) {    
LayoutInflater vi = (LayoutInflater)getSystemService(Context.LAYOUT_INFLATER_SERVICE);    
//or youractivity.getsystemservice      
v = vi.inflate(R.layout.row, null);     
TextView t = (TextView) v.findViewById(R.id.toptext);
    String s = t.getText().toString();
    net.killProcess(s);
}

按钮上的空指针从listView行内的按钮单击侦听器

3 个答案: