当我试图解析json时，它抛出一个空指针异常。当我试图显示值时，也没有显示任何内容。
代码：
public class ParseJSON {
//public static String[] ids;
public static String[] names;
public static String[] message;
public static final String JSON_ARRAY = "users";
// public static final String KEY_ID = "id";
public static final String KEY_NAME = "username";
public static final String KEY_EMAIL = "message";
private JSONArray users = null;
private String json;
public ParseJSON(String json){
this.json = json;
}
protected void parseJSON(){
JSONObject jsonObject=null;
try {
jsonObject = new JSONObject(json);
users = jsonObject.getJSONArray(JSON_ARRAY);
//final String TAG = events.class.getSimpleName();
//Log.d(TAG, "username value: \n" + KEY_NAME);
for(int i=0;i<users.length();i++){
JSONObject jo = users.getJSONObject(i);
// ids[i] = jo.getString(KEY_ID);
names[i] = jo.getString(KEY_NAME);
message[i] = jo.getString(KEY_EMAIL);
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}
但是当我试图显示解析值时，我在一个单独的页面中显示它，如果我可以尝试使用LOGD显示值，它会显示值。
list_view.java
private void sendRequest(){
StringRequest stringRequest = new StringRequest(JSON_URL,
new Response.Listener<String>() {
@Override
public void onResponse(String response) {
showJSON(response);
}
},
new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
Toast.makeText(list_view.this,error.getMessage(),Toast.LENGTH_LONG).show();
}
});
RequestQueue requestQueue = Volley.newRequestQueue(this);
requestQueue.add(stringRequest);
}
private void showJSON(String json){
final String TAG = events.class.getSimpleName();
Log.d(TAG, "showJSON: \n" + json);
ParseJSON pj = new ParseJSON(json);
pj.parseJSON();
CustomList cl = new CustomList(this,ParseJSON.names,ParseJSON.message);
listView.setAdapter(cl);
}
@Override
public void onClick(View v) {
sendRequest();
}
}
这是错误;
04-24 21:49:39.449 15992-15992/? D/events: showJSON:
{"users":[{"username":"varun","message":"hello word, my first message "},{"username":"varun","message":"hello word, my first message "},{"username":"rahul","message":"hello world"},{"username":"rahul","message":"world: its cool"},{"username":"rahul","message":"awesom"},{"username":"rahul","message":"ranom"},{"username":"rahul","message":"randimagain"},{"username":"rahi","message":"is it me again"},{"username":"rahull","message":"hi rahul"},{"username":"rahul","message":"world, am bacj"},{"username":"rahul","message":"hello parents"},{"username":"","message":""},{"username":"","message":""},{"username":"","message":""},{"username":"","message":""},{"username":"","message":""},{"username":"varun","message":"google world"},{"username":"rahul","message":"ollaaa"},{"username":"rahul","message":"ollaaa"},{"username":"rahul","message":"where are others"},{"username":"rahul","message":"where are others"},{"username":"varun","message":"oil spil"},{"username":"varun","message":"phone"},{"username":"vatun","message":"tttt"},{"username":"varun","message":"poiuytrew"},{"username":"rahui","message":"yregh"},{"username":"varun","message":"huiokgddfv"},{"username":"rahi","message":"poiutghklnbfd"},{"username":"rahui","message":"qwerty"},{"username":"varub","message":"hi eat pineapple"},{"username":"varun","message":"hi prabh"},{"username":"rahul","message":"hi world"},{"username":"ggjdjjf","message":"yhvdhhj"},{"username":"tgggg","message":"hhhh"},{"username":"rahul","message":"lqvrl"},{"username":"hhhh","message":"ghh"},{"username":"tff","message":"gg"},{"username":"hfdhn","message":"hnnnme"},{"username":"popo","message":"plpl"},{"username":"rahulpop","message":"op music"},{"username":"rtrt","message":"tyty"},{"username":"hlpo","message":"opop"},{"username":"hlpoghhj","message":"opop"},{"username":"tt","message":"hhh"},{"username":"ttere","message":"hhh"},{"username":"gytgjyg","message":"lajdhd"},{"username":"topo","message":"ptpt"},{"username":"jgj","message":"rtr"},{"username":"ry","message":"yr"},{"username":"ry","message":"yr"},{"username":"y","message":"q"},{"username":"u","message":"t"},{"username":"tt","message":"pp"},{"username":"q","message":"z"},{"username":"w","message":"v"},{"username":"e","message":"e."},{"username":"ui","message":"ui"},{"username":"yi","message":"yi"},{"username":"gg","message":"g"},{"username":"e","message":"e"},{"username":"h","message":"hh"},{"username":"j","message":"j"},{"username":"j","message":"k"},{"username":"v","message":"v"}]}
04-24 21:49:39.459 15992-15992/? D/AndroidRuntime: Shutting down VM
04-24 21:49:39.459 15992-15992/? W/dalvikvm: threadid=1: thread exiting with uncaught exception (group=0x40c1ea68)
04-24 21:49:39.529 15992-15992/? E/AndroidRuntime: FATAL EXCEPTION: main
java.lang.NullPointerException
at com.weavearound.schools.weavearound.ParseJSON.parseJSON(ParseJSON.java:43)
at com.weavearound.schools.weavearound.list_view.showJSON(list_view.java:76)
at com.weavearound.schools.weavearound.list_view.access$000(list_view.java:22)
at com.weavearound.schools.weavearound.list_view$1.onResponse(list_view.java:51)
at com.weavearound.schools.weavearound.list_view$1.onResponse(list_view.java:45)
at com.android.volley.toolbox.StringRequest.deliverResponse(StringRequest.java:67)
at com.android.volley.toolbox.StringRequest.deliverResponse(StringRequest.java:30)
at com.android.volley.ExecutorDelivery$ResponseDeliveryRunnable.run(ExecutorDelivery.java:99)
at android.os.Handler.handleCallback(Handler.java:605)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4517)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:993)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:760)
at dalvik.system.NativeStart.main(Native Method)
04-24 21:49:39.559 403-420/? E/android.os.Debug: !@Dumpstate > dumpstate -k -t -n -z -d -o /data/log/dumpstate_app_error
答案 0 :(得分：0)
你的问题是字符串数组没有初始化。
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