Android文本视图未设置
我现在正在学习Android开发,我想尝试一下我在iOS开发中所做的任何基本程序。问题是获取一个地方的天气条件并在TextView中设置条件 代码Android文本视图未设置,android,android-asynctask,textview,Android,Android Asynctask,Textview,我现在正在学习Android开发,我想尝试一下我在iOS开发中所做的任何基本程序。问题是获取一个地方的天气条件并在TextView中设置条件 代码 package com.bh.weather; import java.io.BufferedReader; import java.io.InputStreamReader; import org.apache.http.HttpResponse; import org.apache.http.client.methods.HttpGet; i
package com.bh.weather;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import org.apache.http.HttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONObject;
import android.os.AsyncTask;
import android.os.Bundle;
import android.app.Activity;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
class WeatherTask extends AsyncTask<String, Void, String> {
protected void onPostExecute(String json) {
try {
JSONObject jsonObject = new JSONObject(json);
String value = jsonObject.getJSONObject("data")
.getJSONArray("current_condition").getJSONObject(0)
.getJSONArray("weatherDesc").getJSONObject(0)
.getString("value");
Log.d("bh", value);
MainActivity m = new MainActivity();
m.setTextView(value);
} catch (Exception e) {
e.printStackTrace();
}
}
@Override
protected String doInBackground(String... urlTojson) {
String json = new String();
try {
DefaultHttpClient defaultClient = new DefaultHttpClient();
HttpGet httpGetRequest = new HttpGet(urlTojson[0]);
HttpResponse httpResponse = defaultClient.execute(httpGetRequest);
BufferedReader reader = new BufferedReader(new InputStreamReader(httpResponse.getEntity().getContent(), "UTF-8"));
json = reader.readLine();
} catch (Exception e) {
e.printStackTrace();
}
return json;
}
}
public class MainActivity extends Activity implements OnClickListener {
private TextView tv = null;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button button = (Button) findViewById(R.id.button1);
button.setOnClickListener(this);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
@Override
public void onClick(View v) {
//changed the API key here to xxxxxxxxxxxxxxxx
new WeatherTask().execute("http://free.worldweatheronline.com/feed/weather.ashx?q=Bangalore,India&format=json&num_of_days=1&key=xxxxxxxxxxxxxxxxx");
}
public void setTextView(String v) {
Log.d("bh","Inside setTextView:"+v);
if(v.equals("")) {
Log.d("bh","Value not received");
}
else {
tv = (TextView) findViewById(R.id.textView3);
tv.setText(v);
}
}
}
活动\u main.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity" >
<TextView
android:id="@+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginTop="22dp"
android:text="@string/title" />
<TextView
android:id="@+id/textView2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_below="@+id/textView1"
android:layout_marginLeft="32dp"
android:layout_marginTop="30dp"
android:text="@string/place_name"
android:textAppearance="?android:attr/textAppearanceLarge" />
<TextView
android:id="@+id/textView3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/textView2"
android:layout_below="@+id/textView2"
android:layout_marginTop="36dp"
android:layout_marginLeft="0dp"
android:text="@string/weather_condition" />
<Button
android:id="@+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/textView1"
android:layout_centerVertical="true"
android:layout_marginTop="140dp"
android:layout_marginLeft="120dp"
android:text="@string/show_weather" />
</RelativeLayout>
正如您从代码中看到的,我在解析后得到值“Clear”(使用Internet权限集)。但由于某些原因,这并没有在TextView中设置。我不知道我在这里犯了什么错误。Logcat正确显示记录的值。请帮忙
干杯。您需要在内部使用构造函数
AsyncTask
传递活动上下文,而不是在AsyncTask内部创建它。将代码更改为:
class WeatherTask extends AsyncTask<String, Void, String> {
public Context context;
public WeatherTask(Context context){
this.context=context;
}
protected void onPostExecute(String json) {
try {
JSONObject jsonObject = new JSONObject(json);
String value = jsonObject.getJSONObject("data")
.getJSONArray("current_condition").getJSONObject(0)
.getJSONArray("weatherDesc").getJSONObject(0)
.getString("value");
Log.d("bh", value);
context.setTextView(value);
} catch (Exception e) {
e.printStackTrace();
}
}
//your code here....
试一试
class WeatherTask扩展了AsyncTask{
主要活动能力;
公共天气任务(主要活动){
这个.mActivity=mActivity;
}
受保护的void onPostExecute(字符串json){
试一试{
JSONObject JSONObject=新的JSONObject(json);
字符串值=jsonObject.getJSONObject(“数据”)
.getJSONArray(“当前条件”).getJSONObject(0)
.getJSONArray(“weatherDesc”).getJSONObject(0)
.getString(“值”);
Log.d(“bh”,值);
mActivity.setTextView(值);
}捕获(例外e){
e、 printStackTrace();
}
}
@凌驾
受保护的字符串doInBackground(字符串…urlTojson){
String json=新字符串();
试一试{
DefaultHttpClient defaultClient=新的DefaultHttpClient();
HttpGet httpGetRequest=新的HttpGet(urlTojson[0]);
HttpResponse HttpResponse=defaultClient.execute(httpGetRequest);
BufferedReader=新的BufferedReader(新的InputStreamReader(httpResponse.getEntity().getContent(),“UTF-8”);
json=reader.readLine();
}捕获(例外e){
e、 printStackTrace();
}
返回json;
}
}
公共类MainActivity扩展活动实现OnClickListener{
私有文本视图tv=null;
@凌驾
创建时受保护的void(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
按钮按钮=(按钮)findViewById(R.id.button1);
setOnClickListener(此);
}
@凌驾
公共布尔onCreateOptions菜单(菜单){
getMenuInflater().充气(R.menu.activity\u主菜单);
返回true;
}
@凌驾
公共void onClick(视图v){
//将此处的API密钥更改为XXXXXXXXXXXXXX
新建WeatherTask(此)。执行(“http://free.worldweatheronline.com/feed/weather.ashx?q=Bangalore,印度&format=json&num_of_days=1&key=XXXXXXXXXXXXXXXXXX”);
}
公共void setTextView(字符串v){
Log.d(“bh”,“内部setTextView:+v”);
如果(v等于(“”){
日志d(“bh”,“未收到的价值”);
}
否则{
tv=(TextView)findViewById(R.id.textView3);
tv.setText(v);
}
}
}
您正在创建MainActivity的新实例并调用其setTextView()
,而不是处理现有实例。哦,那么如何让MainActivity的现有实例设置文本呢?
class WeatherTask extends AsyncTask<String, Void, String> {
public Context context;
public WeatherTask(Context context){
this.context=context;
}
protected void onPostExecute(String json) {
try {
JSONObject jsonObject = new JSONObject(json);
String value = jsonObject.getJSONObject("data")
.getJSONArray("current_condition").getJSONObject(0)
.getJSONArray("weatherDesc").getJSONObject(0)
.getString("value");
Log.d("bh", value);
context.setTextView(value);
} catch (Exception e) {
e.printStackTrace();
}
}
//your code here....
WeatherTask weatherobj=new WeatherTask(MainActivity.this);
weatherobj.execute("http://free.worldweatheronline.com/feed/
weather.ashx?q=Bangalore,India&format=json&num_of_days=1&key=xxxxxxxxxxxxxxxxx");
class WeatherTask extends AsyncTask<String, Void, String> {
MainActivity mActivity;
public WeatherTask(MainActivity mActivity){
this.mActivity=mActivity;
}
protected void onPostExecute(String json) {
try {
JSONObject jsonObject = new JSONObject(json);
String value = jsonObject.getJSONObject("data")
.getJSONArray("current_condition").getJSONObject(0)
.getJSONArray("weatherDesc").getJSONObject(0)
.getString("value");
Log.d("bh", value);
mActivity.setTextView(value);
} catch (Exception e) {
e.printStackTrace();
}
}
@Override
protected String doInBackground(String... urlTojson) {
String json = new String();
try {
DefaultHttpClient defaultClient = new DefaultHttpClient();
HttpGet httpGetRequest = new HttpGet(urlTojson[0]);
HttpResponse httpResponse = defaultClient.execute(httpGetRequest);
BufferedReader reader = new BufferedReader(new InputStreamReader(httpResponse.getEntity().getContent(), "UTF-8"));
json = reader.readLine();
} catch (Exception e) {
e.printStackTrace();
}
return json;
}
}
public class MainActivity extends Activity implements OnClickListener {
private TextView tv = null;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button button = (Button) findViewById(R.id.button1);
button.setOnClickListener(this);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
@Override
public void onClick(View v) {
//changed the API key here to xxxxxxxxxxxxxxxx
new WeatherTask(this).execute("http://free.worldweatheronline.com/feed/weather.ashx?q=Bangalore,India&format=json&num_of_days=1&key=xxxxxxxxxxxxxxxxx");
}
public void setTextView(String v) {
Log.d("bh","Inside setTextView:"+v);
if(v.equals("")) {
Log.d("bh","Value not received");
}
else {
tv = (TextView) findViewById(R.id.textView3);
tv.setText(v);
}
}
}