Android setOnClickListener-应用程序意外停止
当我在代码中使用setOnClickListener作为按钮时,当我启动应用程序时,它会显示Android setOnClickListener-应用程序意外停止,android,onclick,buttonclick,application-shutdown,Android,Onclick,Buttonclick,Application Shutdown,当我在代码中使用setOnClickListener作为按钮时,当我启动应用程序时,它会显示应用程序意外停止 package example.khumbayatabbed; import java.io.BufferedReader; import java.io.InputStream; import java.io.InputStreamReader; import java.util.ArrayList; import java.util.HashMap; import org.apa
应用程序意外停止
package example.khumbayatabbed;
import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.HashMap;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.HttpClient;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.ListActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.Toast;
import android.widget.AdapterView.OnItemClickListener;
public class Category extends ListActivity{
int categ=0;
String[] categories = new String[100];
Button button1;
EditText edittext1;
ArrayList<HashMap<String, String>> mylist = new ArrayList<HashMap<String, String>>();
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
edittext1= (EditText) findViewById(R.id.edittext);
button1 = (Button) findViewById(R.id.button);
button1.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
edittext1.setText("");
Toast.makeText(getApplicationContext(), "Hello",
Toast.LENGTH_SHORT).show();
}
});
// setContentView(R.layout.main);
// Create a crude view - this should really be set via the layout resources
// but since its an example saves declaring them in the XML.
// Set the text and call the connect function.
//call the method to run the data retreival
final String KEY_121 = "http://myurl";
getServerData(KEY_121);
if(mylist.isEmpty())
Toast.makeText(getApplicationContext(), "No more sub categories",
Toast.LENGTH_SHORT).show();
else
display(mylist);
}
private void getServerData(String jason) {
mylist = new ArrayList<HashMap<String, String>>();
InputStream is = null;
String returnString="";
String result = "";
//mylist.clear();
//the year data to send
ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
//http post
try{
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost(jason);
httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
HttpResponse response = httpclient.execute(httppost);
HttpEntity entity = response.getEntity();
is = entity.getContent();
}catch(Exception e){
Log.e("log_tag", "Error in http connection "+e.toString());
}
//convert response to string
try{
BufferedReader reader = new BufferedReader(new InputStreamReader(is,"iso-8859-1"),8);
StringBuilder sb = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
is.close();
result=sb.toString();
}catch(Exception e){
Log.e("log_tag", "Error converting result "+e.toString());
}
//parse json data
try{
JSONArray jArray = new JSONArray(result);
for(int i=0;i<jArray.length();i++){
HashMap<String, String> map = new HashMap<String, String>();
JSONObject json_data = jArray.getJSONObject(i);
Log.i("log_tag","url: "+json_data.getString("url")+
", name: "+json_data.getString("value")
);
//Get an output to the screen
categories[categ++]=json_data.getString("value");
map.put("name", json_data.getString("value"));
map.put("url", json_data.getString("url"));
mylist.add(map);
returnString += jArray.getJSONObject(i).getString("url") + "\n";
}
}catch(JSONException e){
Log.e("log_tag", "Error parsing data "+e.toString());
}
}
private void display(ArrayList<HashMap<String, String>> list)
{
ListAdapter adapter=new SimpleAdapter(this,list,R.layout.list_item2, new String[] {"name"}, new int[]{R.id.cat_name});
setListAdapter(adapter);
final ListView lv = getListView();
lv.setTextFilterEnabled(true);
lv.setOnItemClickListener(new OnItemClickListener() {
@SuppressWarnings("unchecked")
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
HashMap<String, String> tmp = new HashMap<String, String>();
tmp=(HashMap<String, String>)parent.getItemAtPosition(position);
String cat_url=tmp.get("url");
final String KEY_121 = "http://myurl/"+cat_url;
getServerData(KEY_121);
if(mylist.isEmpty())
Toast.makeText(getApplicationContext(), "No more sub categories",
Toast.LENGTH_SHORT).show();
else
display(mylist);
}
});
}
}
main.xml如下所示:
您没有为版面编写setContentView。因此,您无法访问editText1和按钮1。 写一些像
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
在您的主页中调用此用法
Intent myIntent = new Intent(MainPage.this,Category.class);
MainPage.this.startActivity(myIntent);
您没有为布局编写setContentView。因此,您无法访问editText1和按钮1。 写一些像
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
在您的主页中调用此用法
Intent myIntent = new Intent(MainPage.this,Category.class);
MainPage.this.startActivity(myIntent);
在我为按钮添加onclick事件之前,此代码一直有效。即使我为EditText添加了一个操作侦听器,它也会说应用程序意外停止。。。请帮助。在我为按钮添加onclick事件之前,此代码一直有效。即使我为EditText添加了一个操作侦听器,它也会说应用程序意外停止。。。请帮忙。嘿,谢谢你的快速回复。。但是正如您在我的代码中看到的,我已经对setContentView(R.layout.main)进行了注释;陈述如果我取消注释它,它会再次显示“应用程序意外停止”。上面的代码是针对名为category的类的。我有一个主页,我从中调用此页面。这是一个活动。您如何从另一个活动调用此页面。您必须使用startActivity,还必须将此活动名称放入清单文件中您必须添加setContentView(R.layout.main);在绑定mail.xml文件中的任何权重之前。因此,请在绑定编辑文本之前使用这一行,如果它不能解决发送问题,请向我发送在logcat中打印的错误消息。如果我在代码中取消对setContentView(R.layout.main)的注释,并删除与按钮对应的代码和编辑文本,然后删除在取消对setContentView(R.layout.main)的注释之前起作用的代码。还开始给出错误“应用程序意外停止”…在super.onCreate(savedInstanceState)之后立即使用setContentView(R.layout.main);嘿,谢谢你的快速回复。。但是正如您在我的代码中看到的,我已经对setContentView(R.layout.main)进行了注释;陈述如果我取消注释它,它会再次显示“应用程序意外停止”。上面的代码是针对名为category的类的。我有一个主页,我从中调用此页面。这是一个活动。您如何从另一个活动调用此页面。您必须使用startActivity,还必须将此活动名称放入清单文件中您必须添加setContentView(R.layout.main);在绑定mail.xml文件中的任何权重之前。因此,请在绑定编辑文本之前使用这一行,如果它不能解决发送问题,请向我发送在logcat中打印的错误消息。如果我在代码中取消对setContentView(R.layout.main)的注释,并删除与按钮对应的代码和编辑文本,然后删除在取消对setContentView(R.layout.main)的注释之前起作用的代码。还开始给出错误“应用程序意外停止”…在super.onCreate(savedInstanceState)之后立即使用setContentView(R.layout.main);