我已经为 android 创建了 2 个基于 java 的应用程序，它们都可以独立运行。
第一个，一个简单的应用程序，有几个文本字段和带有 onClick 功能的框，可以在页面之间切换，
第二个 JSON 列表(是的，这就是应用程序中的所有内容)
我试图将 JSON 列表应用程序放在第一个应用程序的中间，但是当我单击针对我的 JSON.java 页面的 onClick 按钮时，它崩溃了，但是当我运行 JSON.java 页面时它自己的应用程序，运行良好。
对于我向其中倾倒大量代码向大家表示抱歉，但我是 android 的新手，对它了解不多，所以不确定哪些部分是/不相关的。
主页.Java
package com.example.assent.app;
import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.view.Menu;
import android.view.View;
public class HomePage extends Activity {
public void SelectClient(View view)
{
Intent intent = new Intent(HomePage.this, AndroidJSONParsingActivity.class);
startActivity(intent);
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_home_page);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_home_page, menu);
return true;
}
}
布局 - activity_home_page.xml
<LinearLayout 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"
android:gravity="top"
android:orientation="vertical" >
<TextView
android:id="@+id/textView2"
android:layout_width="wrap_content"
android:layout_height="0dp"
android:layout_gravity="center_horizontal"
android:layout_weight="0.08"
android:text="@string/Home_Text1"
android:textAppearance="?android:attr/textAppearanceLarge" />
<TextView
android:id="@+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:text="@string/Home_Text2"
android:textAppearance="?android:attr/textAppearanceLarge" />
<EditText
android:id="@+id/editText3"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:ems="10"
android:inputType="textPersonName" />
<TableLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="0.06" >
<TableRow
android:id="@+id/tableRow1"
android:layout_width="wrap_content"
android:layout_height="wrap_content" >
</TableRow>
<TableRow
android:id="@+id/tableRow2"
android:layout_width="wrap_content"
android:layout_height="wrap_content" >
</TableRow>
<TableRow
android:id="@+id/tableRow3"
android:layout_width="wrap_content"
android:layout_height="wrap_content" >
</TableRow>
<TableRow
android:id="@+id/tableRow4"
android:layout_width="wrap_content"
android:layout_height="wrap_content" >
</TableRow>
</TableLayout>
<TextView
android:id="@+id/textView4"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:text="@string/Home_Text3"
android:textAppearance="?android:attr/textAppearanceLarge" />
<TextView
android:id="@+id/textView5"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:text="@string/Home_Text4"
android:textAppearance="?android:attr/textAppearanceSmall" />
<EditText
android:id="@+id/editText2"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:ems="10"
android:inputType="textPassword" />
<TableLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="0.09" >
<TableRow
android:id="@+id/TableRow02"
android:layout_width="wrap_content"
android:layout_height="wrap_content" >
</TableRow>
<TableRow
android:id="@+id/TableRow01"
android:layout_width="wrap_content"
android:layout_height="wrap_content" >
</TableRow>
<TableRow
android:id="@+id/TableRow04"
android:layout_width="wrap_content"
android:layout_height="wrap_content" >
</TableRow>
<TableRow
android:id="@+id/TableRow03"
android:layout_width="wrap_content"
android:layout_height="wrap_content" >
</TableRow>
</TableLayout>
<Button
android:id="@+id/button1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:onClick="SelectClient"
android:text="@string/Home_Button1" />
</LinearLayout>
菜单 - activity_home_page.xml
<menu xmlns:android="http://schemas.android.com/apk/res/android">
<item android:id="@+id/menu_settings"
android:title="@string/menu_settings"
android:orderInCategory="100"
android:showAsAction="never" />
</menu>
JSON JAVA - AndroidJSONParsingActivity.java
package com.example.assent.app;
import java.util.ArrayList;
import java.util.HashMap;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.ListActivity;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.TextView;
public class AndroidJSONParsingActivity extends ListActivity {
// url to make request
private static String url = "http://dcc.assentbc.co.uk/GetClients.aspx?SecureID=*******";
// JSON Node names
private static final String TAG_CONTACTS = "Clients";
private static final String TAG_NAME = "CompanyName";
// contacts JSONArray
JSONArray Clients = null;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
// Hashmap for ListView
ArrayList<HashMap<String, String>> contactList = new ArrayList<HashMap<String, String>>();
// Creating JSON Parser instance
JSONParser jParser = new JSONParser();
// getting JSON string from URL
JSONObject json = jParser.getJSONFromUrl(url);
try {
// Getting Array of Contacts
Clients = json.getJSONArray(TAG_CONTACTS);
// looping through All Contacts
for(int i = 0; i < Clients.length(); i++){
JSONObject c = Clients.getJSONObject(i);
// Storing each json item in variable
String name = c.getString(TAG_NAME);
// creating new HashMap
HashMap<String, String> map = new HashMap<String, String>();
// adding each child node to HashMap key => value
map.put(TAG_NAME, name);
// adding HashList to ArrayList
contactList.add(map);
}
} catch (JSONException e) {
e.printStackTrace();
}
/**
* Updating parsed JSON data into ListView
* */
ListAdapter adapter = new SimpleAdapter(this, contactList,
R.layout.list_item,
new String[] { TAG_NAME }, new int[] {
R.id.name });
setListAdapter(adapter);
// selecting single ListView item
ListView lv = getListView();
// Launching new screen on Selecting Single ListItem
lv.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
// getting values from selected ListItem
String name = ((TextView) view.findViewById(R.id.name)).getText().toString();
// Starting new intent
Intent in = new Intent(getApplicationContext(), SingleMenuItemActivity.class);
in.putExtra(TAG_NAME, name);
startActivity(in);
}
});
}
}
JSON 解析器 JAVA - JSONParser.java
package com.example.assent.app;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONException;
import org.json.JSONObject;
import android.util.Log;
public class JSONParser {
static InputStream is = null;
static JSONObject jObj = null;
static String json = "";
// constructor
public JSONParser() {
}
public JSONObject getJSONFromUrl(String url) {
// Making HTTP request
try {
// defaultHttpClient
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(url);
HttpResponse httpResponse = httpClient.execute(httpPost);
HttpEntity httpEntity = httpResponse.getEntity();
is = httpEntity.getContent();
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
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();
json = sb.toString();
} catch (Exception e) {
Log.e("Buffer Error", "Error converting result " + e.toString());
}
// try parse the string to a JSON object
try {
jObj = new JSONObject(json);
} catch (JSONException e) {
Log.e("JSON Parser", "Error parsing data " + e.toString());
}
// return JSON String
return jObj;
}
}
JSON 项目 - SingleMenuItemActivity.java
package com.example.assent.app;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.widget.TextView;
public class SingleMenuItemActivity extends Activity {
// JSON node keys
private static final String TAG_NAME = "CompanyName";
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.single_list_item);
// getting intent data
Intent in = getIntent();
// Get JSON values from previous intent
String name = in.getStringExtra(TAG_NAME);
// Displaying all values on the screen
TextView lblName = (TextView) findViewById(R.id.name_label);
lblName.setText(name);
}
}
布局列表项 - list_item.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="wrap_content"
android:orientation="vertical">
<!-- Name Label -->
<TextView
android:id="@+id/name"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:textColor="#43bd00"
android:textSize="16sp"
android:textStyle="bold"
android:paddingTop="6dip"
android:paddingBottom="2dip" />
</LinearLayout>
主要布局 - main.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="fill_parent"
android:orientation="vertical">
<!-- Main ListView
Always give id value as list(@android:id/list)
-->
<ListView
android:id="@android:id/list"
android:layout_width="fill_parent"
android:layout_height="wrap_content"/>
</LinearLayout>
单项布局 - single_item_list.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<!-- Name Label -->
<TextView android:id="@+id/name_label"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:textSize="25dip"
android:textStyle="bold"
android:paddingTop="10dip"
android:paddingBottom="10dip"
android:textColor="#43bd00"/>
<!-- Description Label -->
<TextView android:id="@+id/email_label"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:textColor="#acacac"/>
<!-- Price Label -->
<TextView android:id="@+id/mobile_label"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:textStyle="bold"/>
</LinearLayout>
我的 list
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.assent.app"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="15" />
<application
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name=".HomePage"
android:label="@string/title_activity_home_page" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name=".MainActivity"
android:label="@string/title_activity_main" >
<meta-data
android:name="android.support.PARENT_ACTIVITY"
android:value="com.example.assent.app.HomePage" />
</activity>
<activity
android:name=".Photos"
android:label="@string/title_activity_photos" >
<meta-data
android:name="android.support.PARENT_ACTIVITY"
android:value="com.example.assent.app.MainActivity" />
</activity>
<activity
android:name=".AudioNotes"
android:label="@string/title_activity_audio_notes" >
<meta-data
android:name="android.support.PARENT_ACTIVITY"
android:value="com.example.assent.app.MainActivity" />
</activity>
<activity
android:name=".Notes"
android:label="@string/title_activity_notes" >
<meta-data
android:name="android.support.PARENT_ACTIVITY"
android:value="com.example.assent.app.MainActivity" />
</activity>
<activity
android:name=".Documents"
android:label="@string/title_activity_documents" >
<meta-data
android:name="android.support.PARENT_ACTIVITY"
android:value="com.example.assent.app.MainActivity" />
</activity>
<activity
android:name=".PhotosSuccess"
android:label="@string/title_activity_photos_success" >
<meta-data
android:name="android.support.PARENT_ACTIVITY"
android:value="com.example.assent.app.MainActivity" />
</activity>
<activity
android:name=".PhotosActivity"
android:label="@string/title_activity_photos" >
<meta-data
android:name="android.support.PARENT_ACTIVITY"
android:value="com.example.assent.app.MainActivity" />
</activity>
<activity
android:name=".Photos_Upload"
android:label="@string/title_activity_photos__upload" >
<meta-data
android:name="android.support.PARENT_ACTIVITY"
android:value="com.example.assent.app.MainActivity" />
</activity>
<activity
android:name=".ImageUpload"
android:label="@string/title_activity_image_upload" >
<meta-data
android:name="android.support.PARENT_ACTIVITY"
android:value="com.example.assent.app.MainActivity" />
</activity>
<activity
android:name=".Notes_Upload"
android:label="@string/title_activity_notes__upload" >
<meta-data
android:name="android.support.PARENT_ACTIVITY"
android:value="com.example.assent.app.MainActivity" />
</activity>
<activity
android:name=".SelectClient"
android:label="@string/title_activity_select_client" >
<meta-data
android:name="android.support.PARENT_ACTIVITY"
android:value="com.example.assent.app.HomePage" />
</activity>
<activity
android:label="@string/app_name"
android:name=".AndroidJSONParsingActivity" >
<intent-filter >
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<!-- Single List Item View -->
<activity
android:label="Single Menu Item"
android:name=".SingleMenuItemActivity" >
</activity>
</application>
<uses-permission android:name="android.permission.INTERNET" />
</manifest>
我的 ECLIPSE 日志
11-22 12:10:56.638: D/dalvikvm(381): GC_FOR_ALLOC freed 88K, 3% free 6478K/6663K, paused 56ms
11-22 12:10:56.648: I/dalvikvm-heap(381): Grow heap (frag case) to 6.872MB for 513744-byte allocation
11-22 12:10:56.738: D/dalvikvm(381): GC_FOR_ALLOC freed 2K, 3% free 6977K/7175K, paused 53ms
11-22 12:10:56.868: D/dalvikvm(381): GC_CONCURRENT freed <1K, 3% free 6977K/7175K, paused 4ms+22ms
11-22 12:10:56.938: D/AndroidRuntime(381): Shutting down VM
11-22 12:10:56.938: W/dalvikvm(381): threadid=1: thread exiting with uncaught exception (group=0x40014760)
11-22 12:10:56.958: E/AndroidRuntime(381): FATAL EXCEPTION: main
11-22 12:10:56.958: E/AndroidRuntime(381): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.assent.app/com.example.assent.app.AndroidJSONParsingActivity}: android.os.NetworkOnMainThreadException
11-22 12:10:56.958: E/AndroidRuntime(381): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1815)
11-22 12:10:56.958: E/AndroidRuntime(381): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1831)
11-22 12:10:56.958: E/AndroidRuntime(381): at android.app.ActivityThread.access$500(ActivityThread.java:122)
11-22 12:10:56.958: E/AndroidRuntime(381): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1024)
11-22 12:10:56.958: E/AndroidRuntime(381): at android.os.Handler.dispatchMessage(Handler.java:99)
11-22 12:10:56.958: E/AndroidRuntime(381): at android.os.Looper.loop(Looper.java:132)
11-22 12:10:56.958: E/AndroidRuntime(381): at android.app.ActivityThread.main(ActivityThread.java:4123)
11-22 12:10:56.958: E/AndroidRuntime(381): at java.lang.reflect.Method.invokeNative(Native Method)
11-22 12:10:56.958: E/AndroidRuntime(381): at java.lang.reflect.Method.invoke(Method.java:491)
11-22 12:10:56.958: E/AndroidRuntime(381): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:841)
11-22 12:10:56.958: E/AndroidRuntime(381): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:599)
11-22 12:10:56.958: E/AndroidRuntime(381): at dalvik.system.NativeStart.main(Native Method)
11-22 12:10:56.958: E/AndroidRuntime(381): Caused by: android.os.NetworkOnMainThreadException
11-22 12:10:56.958: E/AndroidRuntime(381): at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1077)
11-22 12:10:56.958: E/AndroidRuntime(381): at java.net.InetAddress.lookupHostByName(InetAddress.java:477)
11-22 12:10:56.958: E/AndroidRuntime(381): at java.net.InetAddress.getAllByNameImpl(InetAddress.java:277)
11-22 12:10:56.958: E/AndroidRuntime(381): at java.net.InetAddress.getAllByName(InetAddress.java:249)
11-22 12:10:56.958: E/AndroidRuntime(381): at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:136)
11-22 12:10:56.958: E/AndroidRuntime(381): at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164)
11-22 12:10:56.958: E/AndroidRuntime(381): at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119)
11-22 12:10:56.958: E/AndroidRuntime(381): at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:360)
11-22 12:10:56.958: E/AndroidRuntime(381): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555)
11-22 12:10:56.958: E/AndroidRuntime(381): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487)
11-22 12:10:56.958: E/AndroidRuntime(381): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465)
11-22 12:10:56.958: E/AndroidRuntime(381): at com.example.assent.app.JSONParser.getJSONFromUrl(JSONParser.java:38)
11-22 12:10:56.958: E/AndroidRuntime(381): at com.example.assent.app.AndroidJSONParsingActivity.onCreate(AndroidJSONParsingActivity.java:46)
11-22 12:10:56.958: E/AndroidRuntime(381): at android.app.Activity.performCreate(Activity.java:4397)
11-22 12:10:56.958: E/AndroidRuntime(381): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1048)
11-22 12:10:56.958: E/AndroidRuntime(381): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1779)
11-22 12:10:56.958: E/AndroidRuntime(381): ... 11 more
11-22 12:11:00.760: I/Process(381): Sending signal. PID: 381 SIG: 9
再次对代码转储表示抱歉，希望有人能指出我正确的方向
最佳答案
推荐使用AsyncTask用于网络操作。 在 Honey Comb 之前，它不会给出任何错误，但从 HoneyComb 版本开始，主 UI 线程上的网络操作将导致 NetworkOnUIthread 异常。
所以调用你的:JSONObject json = jParser.getJSONFromUrl(url);到异步任务的 doInBackGround() 方法，并使用 OnPostExecute 方法中的结果更新您的 UI。
关于android - 将一个 Android JSON 应用程序迁移到 Android 中的一个简单应用程序，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/13512329/