我有這樣的活動代碼:不能使用全局變量在我的應用程序
public class TopJokes extends Activity {
public class Globals extends Application{
String[] myStringArray = {"a","b","c","a","b","c","a","b","c","a","b","c","a","b","c","a","b","c"};
public String[] getMyStringArray() {
return myStringArray;
}
public void setMyStringArray(String[] myStringArray) {
this.myStringArray = myStringArray;
}
}
String[] myStringArray = {"a","b","c","a","b","c","a","b","c","a","b","c","a","b","c","a","b","c"};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_top_jokes);
Globals globals = (Globals)getApplication();
new loadJson().execute();
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,
android.R.layout.simple_list_item_1, globals.getMyStringArray());
ListView listView = (ListView) findViewById(R.id.topJokesList);
listView.setAdapter(adapter);
listView.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
// When clicked, show a toast with the TextView text
Toast.makeText(getApplicationContext(),
((TextView) view).getText(), Toast.LENGTH_SHORT).show();
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.top_jokes, menu);
return true;
}
public class loadJson extends AsyncTask<Void, Integer, String>{
@Override
protected String doInBackground(Void... params) {
URL u;
StringBuffer buffer = new StringBuffer();
try {
u = new URL("https://site.com/android/britishJokes/showJokes.php");
URLConnection conn = u.openConnection();
BufferedReader in = new BufferedReader(
new InputStreamReader(
conn.getInputStream()));
String inputLine;
while ((inputLine = in.readLine()) != null)
buffer.append(inputLine);
in.close();
}catch(Exception e){
e.printStackTrace();
}
return buffer.toString();
}
protected void onPostExecute(String buffer) {
JSONArray jsonArray = new JSONArray();
try {
jsonArray = new JSONArray(buffer);
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
System.out.println("JSONarray: " + jsonArray);
String[] newJokes = null;
for (int i = 0; i < jsonArray.length(); i++) {
try {
newJokes[i] = jsonArray.getJSONObject(i).toString();
} catch (JSONException e) {
e.printStackTrace();
}
}
myStringArray = newJokes;
}
}
}
我已經創建的類Globals
- 應該保持全局變量。
這裏是我如何在清單中聲明它:
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.gs.britishjokes"
android:versionCode="1"
android:versionName="1.0"
android:name=".Globals">
的問題是,當我嘗試訪問全局變量myStringArray
在這行: ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, globals.getMyStringArray());
我得到噸的錯誤和我的不明白什麼是錯的。
我很確定我錯過了一些非常小的東西,但作爲一個初學者,我無法發現它。
這裏是日誌:
02-09 12:00:22.627: E/AndroidRuntime(3249): FATAL EXCEPTION: main
02-09 12:00:22.627: E/AndroidRuntime(3249): Process: com.gs.britishjokes, PID: 3249
02-09 12:00:22.627: E/AndroidRuntime(3249): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.gs.britishjokes/com.gs.britishjokes.TopJokes}: java.lang.ClassCastException: android.app.Application cannot be cast to com.gs.britishjokes.TopJokes$Globals
02-09 12:00:22.627: E/AndroidRuntime(3249): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2176)
02-09 12:00:22.627: E/AndroidRuntime(3249): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2226)
02-09 12:00:22.627: E/AndroidRuntime(3249): at android.app.ActivityThread.access$700(ActivityThread.java:135)
02-09 12:00:22.627: E/AndroidRuntime(3249): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1397)
02-09 12:00:22.627: E/AndroidRuntime(3249): at android.os.Handler.dispatchMessage(Handler.java:102)
02-09 12:00:22.627: E/AndroidRuntime(3249): at android.os.Looper.loop(Looper.java:137)
02-09 12:00:22.627: E/AndroidRuntime(3249): at android.app.ActivityThread.main(ActivityThread.java:4998)
02-09 12:00:22.627: E/AndroidRuntime(3249): at java.lang.reflect.Method.invokeNative(Native Method)
02-09 12:00:22.627: E/AndroidRuntime(3249): at java.lang.reflect.Method.invoke(Method.java:515)
02-09 12:00:22.627: E/AndroidRuntime(3249): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:777)
02-09 12:00:22.627: E/AndroidRuntime(3249): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:593)
02-09 12:00:22.627: E/AndroidRuntime(3249): at dalvik.system.NativeStart.main(Native Method)
02-09 12:00:22.627: E/AndroidRuntime(3249): Caused by: java.lang.ClassCastException: android.app.Application cannot be cast to com.gs.britishjokes.TopJokes$Globals
02-09 12:00:22.627: E/AndroidRuntime(3249): at com.gs.britishjokes.TopJokes.onCreate(TopJokes.java:76)
02-09 12:00:22.627: E/AndroidRuntime(3249): at android.app.Activity.performCreate(Activity.java:5243)
02-09 12:00:22.627: E/AndroidRuntime(3249): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
02-09 12:00:22.627: E/AndroidRuntime(3249): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2140)
02-09 12:00:22.627: E/AndroidRuntime(3249): ... 11 more
請給我一個線索。我迷路了!
讓這個類擴展'Application'。 – nKn
和'Globals'類應該是一個靜態類裏面的活動或寫它作爲單獨的java文件... –
@GopalRao我只是把它'靜態'我;米仍然得到相同的錯誤:( – chility