无法使用java实例化活动组件信息,android
更新 像个白痴一样,我没有注意到logCat。 问题来自我导航到的页面,而不是意图本身,我是在setContentView代码有机会在onContentLoad()中运行之前声明了一些代码 谢谢你的帮助 我知道以前有人问过这个问题,但我已经关注了很多关于这个话题的帖子;但似乎找不到正确的答案。 我试图从我的主活动页面导航到我的ViewFeeds页面;但它抛出了上述错误 有趣的是,我已经有了在页面之间导航的代码,而且它可以工作。但是当我为另一个类复制这段代码时,它抛出了上面的错误 MainActivity代码(我从中导航的代码): ViewFeeds类(我要导航到的类):无法使用java实例化活动组件信息,android,java,android,Java,Android,更新 像个白痴一样,我没有注意到logCat。 问题来自我导航到的页面,而不是意图本身,我是在setContentView代码有机会在onContentLoad()中运行之前声明了一些代码 谢谢你的帮助 我知道以前有人问过这个问题,但我已经关注了很多关于这个话题的帖子;但似乎找不到正确的答案。 我试图从我的主活动页面导航到我的ViewFeeds页面;但它抛出了上述错误 有趣的是,我已经有了在页面之间导航的代码,而且它可以工作。但是当我为另一个类复制这段代码时,它抛出了上面的错误 MainActi
package com.example.rsa应用程序;
导入java.io.BufferedReader;
导入java.io.FileNotFoundException;
导入java.io.IOException;
导入java.io.InputStream;
导入java.io.InputStreamReader;
导入java.util.ArrayList;
导入android.app.ActionBar;
导入android.app.Activity;
导入android.os.Bundle;
导入android.widget.ArrayAdapter;
导入android.widget.ListView;
导入android.widget.TextView;
公共类ViewFeeds扩展了活动{
//保存所有数据的数组。。。
ArrayList items=新建ArrayList();
ListView lv=(ListView)findViewById(R.id.listView1);
创建时受保护的void(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.viewfeeds);
ActionBar ActionBar=getActionBar();
actionBar.hide();
items=newarraylist();
字符串ret=“”;
试一试{
InputStream InputStream=openFileInput(“Teams.txt”);
InputStreamReader InputStreamReader=新的InputStreamReader(inputStream);
BufferedReader BufferedReader=新的BufferedReader(inputStreamReader);
字符串receiveString=“”;
StringBuilder StringBuilder=新的StringBuilder();
//Toast.makeText(MainActivity.this、receiveString、Toast.LENGTH_LONG.show();
试一试{
而((receiveString=bufferedReader.readLine())!=null){
items.add(receiveString);
stringBuilder.append(receiveString+“\r\n”);
}
}捕获(IOE异常){
//TODO自动生成的捕捉块
e、 printStackTrace();
}
inputStream.close();
//ret保存文件中的每一行文本。。。
ret=stringBuilder.toString();
TextView txt=(TextView)findViewById(R.id.textView6);
txt.setText(ret);
ArrayAdapter ArrayAdapter=新的ArrayAdapter(
这
android.R.layout.simple\u list\u item\u 1,
项目);
低压设置适配器(阵列适配器);
}catch(filenotfounde异常){
//TODO自动生成的捕捉块
e、 printStackTrace();
}捕获(IOE异常){
//TODO自动生成的捕捉块
e、 printStackTrace();
}
}
}
android清单(我在声明引用的部分上方添加了一条注释):
这是他的logcat:
08-07 16:27:02.512: E/AndroidRuntime(2321): FATAL EXCEPTION: main
08-07 16:27:02.512: E/AndroidRuntime(2321): Process: com.example.rssapplication, PID: 2321
08-07 16:27:02.512: E/AndroidRuntime(2321): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.rssapplication/com.example.rssapplication.ViewFeeds}: java.lang.NullPointerException
08-07 16:27:02.512: E/AndroidRuntime(2321): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2231)
08-07 16:27:02.512: E/AndroidRuntime(2321): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2363)
08-07 16:27:02.512: E/AndroidRuntime(2321): at android.app.ActivityThread.access$900(ActivityThread.java:161)
08-07 16:27:02.512: E/AndroidRuntime(2321): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1265)
08-07 16:27:02.512: E/AndroidRuntime(2321): at android.os.Handler.dispatchMessage(Handler.java:102)
08-07 16:27:02.512: E/AndroidRuntime(2321): at android.os.Looper.loop(Looper.java:157)
08-07 16:27:02.512: E/AndroidRuntime(2321): at android.app.ActivityThread.main(ActivityThread.java:5356)
08-07 16:27:02.512: E/AndroidRuntime(2321): at java.lang.reflect.Method.invokeNative(Native Method)
08-07 16:27:02.512: E/AndroidRuntime(2321): at java.lang.reflect.Method.invoke(Method.java:515)
08-07 16:27:02.512: E/AndroidRuntime(2321): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1265)
08-07 16:27:02.512: E/AndroidRuntime(2321): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1081)
08-07 16:27:02.512: E/AndroidRuntime(2321): at dalvik.system.NativeStart.main(Native Method)
08-07 16:27:02.512: E/AndroidRuntime(2321): Caused by: java.lang.NullPointerException
08-07 16:27:02.512: E/AndroidRuntime(2321): at android.app.Activity.findViewById(Activity.java:1965)
08-07 16:27:02.512: E/AndroidRuntime(2321): at com.example.rssapplication.ViewFeeds.<init>(ViewFeeds.java:20)
08-07 16:27:02.512: E/AndroidRuntime(2321): at java.lang.Class.newInstanceImpl(Native Method)
08-07 16:27:02.512: E/AndroidRuntime(2321): at java.lang.Class.newInstance(Class.java:1208)
08-07 16:27:02.512: E/AndroidRuntime(2321): at android.app.Instrumentation.newActivity(Instrumentation.java:1079)
08-07 16:27:02.512: E/AndroidRuntime(2321): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2222)
08-07 16:27:02.512: E/AndroidRuntime(2321): ... 11 more
08-0716:27:02.512:E/AndroidRuntime(2321):致命异常:main
08-07 16:27:02.512:E/AndroidRuntime(2321):进程:com.example.rsa应用程序,PID:2321
08-07 16:27:02.512:E/AndroidRuntime(2321):java.lang.RuntimeException:无法实例化活动组件信息{com.example.rssapplication/com.example.rssapplication.ViewFeeds}:java.lang.NullPointerException
08-07 16:27:02.512:E/AndroidRuntime(2321):在android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2231)
08-07 16:27:02.512:E/AndroidRuntime(2321):在android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2363)
08-07 16:27:02.512:E/AndroidRuntime(2321):在android.app.ActivityThread.access$900(ActivityThread.java:161)
08-07 16:27:02.512:E/AndroidRuntime(2321):在android.app.ActivityThread$H.handleMessage(ActivityThread.java:1265)
08-07 16:27:02.512:E/AndroidRuntime(2321):在android.os.Handler.dispatchMessage(Handler.java:102)上
08-07 16:27:02.512:E/AndroidRuntime(2321):在android.os.Looper.loop(Looper.java:157)上
08-07 16:27:02.512:E/AndroidRuntime(2321):位于android.app.ActivityThread.main(ActivityThread.java:5356)
08-07 16:27:02.512:E/AndroidRuntime(2321):位于java.lang.reflect.Method.Invokenactive(本机方法)
08-07 16:27:02.512:E/AndroidRuntime(2321):位于java.lang.reflect.Method.invoke(Method.java:515)
08-07 16:27:02.512:E/AndroidRuntime(2321):在com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1265)
08-07 16:27:02.512:E/AndroidRuntime(2321):位于com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1081)
08-07 16:27:02.512:E/AndroidRuntime(2321):在dalvik.system.NativeStart.main(本机方法)
08-07 16:27:02.512:E/AndroidRuntime(2321):由以下原因引起:java.lang.NullPointerException
08-07 16:27:02.512:E/AndroidRuntime(2321):在android.app.Activity.findViewById(Activity.java:1965)
08-07 16:27:02.512:E/AndroidRuntime(2321):在com.example.rssapplication.ViewFeeds。(ViewFeeds.java:20)
08-07 16:27:02.512:E/AndroidRuntime(2321):位于java.lang.Class.newInstanceImpl(N
package com.example.rssapplication;
import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import android.app.ActionBar;
import android.app.Activity;
import android.os.Bundle;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.TextView;
public class ViewFeeds extends Activity{
//The array which holds all of the data...
ArrayList<String> items = new ArrayList<String>();
ListView lv = (ListView) findViewById(R.id.listView1);
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.viewfeeds);
ActionBar actionBar = getActionBar();
actionBar.hide();
items = new ArrayList<String>();
String ret = "";
try {
InputStream inputStream = openFileInput("Teams.txt");
InputStreamReader inputStreamReader = new InputStreamReader(inputStream);
BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
String receiveString = "";
StringBuilder stringBuilder = new StringBuilder();
// Toast.makeText(MainActivity.this, receiveString, Toast.LENGTH_LONG).show();
try {
while ( (receiveString = bufferedReader.readLine()) != null ) {
items.add(receiveString);
stringBuilder.append(receiveString + "\r\n");
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
inputStream.close();
//ret holds each line of text from the file...
ret = stringBuilder.toString();
TextView txt = (TextView) findViewById(R.id.textView6);
txt.setText(ret);
ArrayAdapter<String> arrayAdapter = new ArrayAdapter<String>(
this,
android.R.layout.simple_list_item_1,
items);
lv.setAdapter(arrayAdapter);
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.rssapplication"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="19" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"></uses-permission>
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.INTERNET"></uses-permission>
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"></uses-permission>
<uses-permission android:name="android.permission.READ_PHONE_STATE"></uses-permission>
<uses-permission android:name="android.permission.DOWNLOAD_WITHOUT_NOTIFICATION" />
<application
android:allowBackup="true"
android:icon="@drawable/sportsoccericon"
android:label="@string/app_name"
android:theme="@style/AppTheme"
android:screenOrientation="portrait"
>
<activity
android:name="com.example.rssapplication.MainActivity"
android:label="@string/app_name"
>
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:name="com.example.rssapplication.SelectTeams" android:label="@string/app_name">
<intent-filter>
<action android:name="android.intent.action.MainActivity" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>
</activity>
<!-- This is where I am creating the intent to navigate from main, to viewfeeds -->
<activity android:name="com.example.rssapplication.ViewFeeds" android:label="@string/app_name">
<intent-filter>
<action android:name="android.intent.action.MainActivity" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>
</activity>
<activity android:name="com.example.rssapplication.ShowArticle" android:label="@string/app_name"
android:parentActivityName="com.example.rssapplication.MyAdapter"
>
<!-- <meta-data
android:name="android.support.PARENT_ACTIVITY"
android:value="com.example.rssapplication.MyAdapter" />-->
<!-- <intent-filter>
<action android:name="android.intent.action.VIEW" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter> -->
</activity>
</application>
</manifest>
08-07 16:27:02.512: E/AndroidRuntime(2321): FATAL EXCEPTION: main
08-07 16:27:02.512: E/AndroidRuntime(2321): Process: com.example.rssapplication, PID: 2321
08-07 16:27:02.512: E/AndroidRuntime(2321): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.rssapplication/com.example.rssapplication.ViewFeeds}: java.lang.NullPointerException
08-07 16:27:02.512: E/AndroidRuntime(2321): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2231)
08-07 16:27:02.512: E/AndroidRuntime(2321): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2363)
08-07 16:27:02.512: E/AndroidRuntime(2321): at android.app.ActivityThread.access$900(ActivityThread.java:161)
08-07 16:27:02.512: E/AndroidRuntime(2321): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1265)
08-07 16:27:02.512: E/AndroidRuntime(2321): at android.os.Handler.dispatchMessage(Handler.java:102)
08-07 16:27:02.512: E/AndroidRuntime(2321): at android.os.Looper.loop(Looper.java:157)
08-07 16:27:02.512: E/AndroidRuntime(2321): at android.app.ActivityThread.main(ActivityThread.java:5356)
08-07 16:27:02.512: E/AndroidRuntime(2321): at java.lang.reflect.Method.invokeNative(Native Method)
08-07 16:27:02.512: E/AndroidRuntime(2321): at java.lang.reflect.Method.invoke(Method.java:515)
08-07 16:27:02.512: E/AndroidRuntime(2321): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1265)
08-07 16:27:02.512: E/AndroidRuntime(2321): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1081)
08-07 16:27:02.512: E/AndroidRuntime(2321): at dalvik.system.NativeStart.main(Native Method)
08-07 16:27:02.512: E/AndroidRuntime(2321): Caused by: java.lang.NullPointerException
08-07 16:27:02.512: E/AndroidRuntime(2321): at android.app.Activity.findViewById(Activity.java:1965)
08-07 16:27:02.512: E/AndroidRuntime(2321): at com.example.rssapplication.ViewFeeds.<init>(ViewFeeds.java:20)
08-07 16:27:02.512: E/AndroidRuntime(2321): at java.lang.Class.newInstanceImpl(Native Method)
08-07 16:27:02.512: E/AndroidRuntime(2321): at java.lang.Class.newInstance(Class.java:1208)
08-07 16:27:02.512: E/AndroidRuntime(2321): at android.app.Instrumentation.newActivity(Instrumentation.java:1079)
08-07 16:27:02.512: E/AndroidRuntime(2321): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2222)
08-07 16:27:02.512: E/AndroidRuntime(2321): ... 11 more
ListView lv = (ListView) findViewById(R.id.listView1);
public class ViewFeeds extends Activity {
private ArrayList<String> items = new ArrayList<String>();
private ListView lv;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.viewfeeds);
lv = (ListView) findViewById(R.id.listView1);
...
}
...
}
ListView lv = (ListView) findViewById(R.id.listView1);
ActionBar actionBar = getSupportActionBar();