Java 在AsyncTask中填充数组时出现Android错误
我想填充一个数组,以便将结果附加到Java 在AsyncTask中填充数组时出现Android错误,java,android,arrays,android-asynctask,Java,Android,Arrays,Android Asynctask,我想填充一个数组,以便将结果附加到TextView,但应用程序不断崩溃: 04-02 23:45:29.286: E/AndroidRuntime(6620): FATAL EXCEPTION: AsyncTask #3 04-02 23:45:29.286: E/AndroidRuntime(6620): java.lang.RuntimeException: An error occured while executing doInBackground() 04-02 23:45:29.28
TextView
,但应用程序不断崩溃:
04-02 23:45:29.286: E/AndroidRuntime(6620): FATAL EXCEPTION: AsyncTask #3
04-02 23:45:29.286: E/AndroidRuntime(6620): java.lang.RuntimeException: An error occured while executing doInBackground()
04-02 23:45:29.286: E/AndroidRuntime(6620): at android.os.AsyncTask$3.done(AsyncTask.java:200)
04-02 23:45:29.286: E/AndroidRuntime(6620): at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:274)
04-02 23:45:29.286: E/AndroidRuntime(6620): at java.util.concurrent.FutureTask.setException(FutureTask.java:125)
04-02 23:45:29.286: E/AndroidRuntime(6620): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:308)
04-02 23:45:29.286: E/AndroidRuntime(6620): at java.util.concurrent.FutureTask.run(FutureTask.java:138)
04-02 23:45:29.286: E/AndroidRuntime(6620): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1088)
04-02 23:45:29.286: E/AndroidRuntime(6620): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:581)
04-02 23:45:29.286: E/AndroidRuntime(6620): at java.lang.Thread.run(Thread.java:1019)
04-02 23:45:29.286: E/AndroidRuntime(6620): Caused by: java.lang.NullPointerException
04-02 23:45:29.286: E/AndroidRuntime(6620): at com.gettford.community.MessageActivity$Mensajes.doInBackground(MessageActivity.java:166)
04-02 23:45:29.286: E/AndroidRuntime(6620): at com.gettford.community.MessageActivity$Mensajes.doInBackground(MessageActivity.java:1)
04-02 23:45:29.286: E/AndroidRuntime(6620): at android.os.AsyncTask$2.call(AsyncTask.java:185)
04-02 23:45:29.286: E/AndroidRuntime(6620): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:306)
04-02 23:45:29.286: E/AndroidRuntime(6620): ... 4 more
我有两条线:
public String[] mensa;
public String[] NomUsuario;
然后我在doInBackround中执行AsynTask:
// Retrieve JSON Objects from the given URL address
jsonobject = JSONfunctions
.getJSONfromURL("http://www.gettford.net/comunidad/api/chat_conv.php?user="+usuarioID+"&id="+idsala);
try {
// Locate the array name in JSON
jsonarray = jsonobject.getJSONArray("lista");
for (int i = 0; i < jsonarray.length(); i++) {
//HashMap<String, String> map = new HashMap<String, String>();
jsonobject = jsonarray.getJSONObject(i);
// Retrive JSON Objects
//usuario = jsonobject.getString("Nombre");
mensa[i] = jsonobject.getString("mensaje");
NomUsuario[i] = jsonobject.getString("NomUsuario");
Log.i("mensaje",mensa[i]);
}
} catch (JSONException e) {
Log.e("Error", e.getMessage());
e.printStackTrace();
}
return null;
}
@Override
protected void onPostExecute(Void args) {
lblMessage.setText("");
for (int i= 0; i < mensa.length; i++){
lblMessage.append(NomUsuario[i]+": "+mensa[i] + "\n");
}
}
谢谢你的帮助
谢谢 您应该在for循环之前添加
mensa=newstring[jsonarray.length()]
。试试这个
将mensa
和nomusario
初始化字符串数组大小放在for循环之前
mensa = new String[jsonarray.length()];
NomUsuario = new String[jsonarray.length()];
for (int i = 0; i < jsonarray.length(); i++) {
mensa=新字符串[jsonarray.length()];
nomusario=新字符串[jsonarray.length()];
for(int i=0;i
您尚未初始化任何阵列
jsonarray = jsonobject.getJSONArray("lista");
if (jsonarray.length() > 0) {
// Initialized both array if the size of that JSONArray is grater then 0
mensa = new String[jsonarray.length()]
NomUsuario= new String[jsonarray.length()]
for (int i = 0; i < jsonarray.length(); i++) {
jsonobject = jsonarray.getJSONObject(i);
mensa[i] = jsonobject.getString("mensaje");
NomUsuario[i] = jsonobject.getString("NomUsuario");
Log.i("mensaje",mensa[i]);
}
}
jsonarray=jsonobject.getJSONArray(“lista”);
if(jsonarray.length()>0){
//如果JSONArray的大小大于0,则初始化两个数组
mensa=新字符串[jsonarray.length()]
nomusario=新字符串[jsonarray.length()]
for(int i=0;i
您刚刚忘记初始化数组变量。在try块启动时,您需要初始化数组变量,如下所示:
try {
// Locate the array name in JSON
mensa = new String[jsonarray.length()]; // Add this line.
NomUsuario = new String[jsonarray.length()]; // Add this line.
这是一个mensa[i]=jsonobject.getString(“mensaje”);您没有初始化
mensa
只是声明它是公共的String[]mensa;
谢谢,具体是怎么做的?我还以为它是由mensa[i]=jsonobject.getString(“mensaje”)初始化的呢@DouglasRoos看看这些文档,最好使用list@DouglasRoos,在这一行中,您正在向未初始化的数组添加值,原因是您得到了空指针。您还应该初始化Nomusario。@DouglasroosThank,是的,现在正在工作,非常感谢您的帮助。我不知道如何在google上查找它。和它战斗了将近2个小时
try {
// Locate the array name in JSON
mensa = new String[jsonarray.length()]; // Add this line.
NomUsuario = new String[jsonarray.length()]; // Add this line.