我正在登录屏幕和主菜单屏幕。现在我一直工作，直到我尝试实现一个方法，如果用户登录或不。根据logcat的主要问题是nullpointerexception，我不能为我的生活如何解决这个问题。如果有人能给我一些很棒的意见。在这一点上任何帮助都会很棒。
以下是我的主菜单活动：
package com.chonbonstudios.LOLTOOLs;
import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.content.SharedPreferences;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.TextView;
public class TitleMenu extends Activity {
TextView SummonerId;
TextView SummonerName;
TextView SummonerLevel;
long SummonerIdA = 0;
String SummonerNameA = "";
long SummonerLevelA = 0;
int profileIconIdA = 0;
SharedPreferences data;
SharedPreferences data1;
SharedPreferences data2;
SharedPreferences data3;
SharedPreferences data4;
boolean loggedIn = false;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
data4 = getSharedPreferences("LoggedInStatus", 0);
loggedIn = data4.getBoolean("LoggedInStatus", false);
if (loggedIn == true){
} else {
startActivity(new Intent(TitleMenu.this, LoginActivity.class));
this.finish();
}
SummonerIdA = getIntent().getLongExtra("SummonerIdTag", 0);
SummonerNameA = getIntent().getStringExtra("SummonerNameTag");
SummonerLevelA = getIntent().getLongExtra("SummonerLevelTag", 0);
profileIconIdA = getIntent().getIntExtra("SummonerProfileIconIdTag", 0);
SharedPreferences.Editor editor = data.edit();
editor.putLong("SummonerIdTag", SummonerIdA);
editor.commit();
finish();
SharedPreferences.Editor editor1 = data1.edit();
editor1.putString("SummonerNameTag", SummonerNameA);
editor1.commit();
finish();
SharedPreferences.Editor editor2 = data2.edit();
editor2.putLong("SummonerLevelTag", SummonerLevelA);
editor2.commit();
finish();
SharedPreferences.Editor editor3 = data3.edit();
editor3.putInt("SummonerProfileIconIdTag", profileIconIdA);
editor3.commit();
finish();
data = getSharedPreferences("SummonerIdTag", 0);
SummonerIdA = data.getLong("SummonerIdTag", 0);
data1 = getSharedPreferences("SummonerNameTag", 0);
SummonerNameA = data1.getString("SummonerNameTag", "");
data2 = getSharedPreferences("SummonerLevelTag", 0);
SummonerLevelA = data2.getLong("SummonerLevelTag", 0);
data3 = getSharedPreferences("SummonerProfileIconIdTag", 0);
profileIconIdA = data3.getInt("SummonerProfileIconIdTag", 0);
setContentView(R.layout.activity_title_menu);
SummonerId = (TextView) findViewById(R.id.txtSummonerId);
SummonerLevel = (TextView) findViewById(R.id.txtSummonerLevel);
SummonerName = (TextView) findViewById(R.id.txtSummonerName);
SummonerId.setText(String.valueOf("My Id: " + SummonerIdA));
SummonerLevel.setText(String.valueOf(SummonerLevelA));
SummonerName.setText(String.valueOf(SummonerNameA));
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.title_menu, menu);
return true;
}
public boolean onOptionsItemSelected(MenuItem item) {
// Handle item selection
switch (item.getItemId()) {
case R.id.action_LofOff:
startActivity(new Intent(TitleMenu.this, LoginActivity.class));
this.finish();
default:
return super.onOptionsItemSelected(item);
}
}
@Override
public void onBackPressed() {
Intent intent = new Intent(Intent.ACTION_MAIN);
intent.addCategory(Intent.CATEGORY_HOME);
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(intent);
}
}
和我的登录活动：
package com.chonbonstudios.LOLTOOLs;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.Activity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.content.SharedPreferences;
import android.graphics.Typeface;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Spinner;
import android.widget.TextView;
import android.widget.Toast;
public class LoginActivity extends Activity implements OnItemSelectedListener {
public String array_spinner[];
Button Login;
EditText Name;
String loginName = "";
String url ="";
TextView one;
TextView two;
Spinner Area;
String AreaCode;
// JSON Node names
private static final String TAG_SUMMONERID = "id";
private static final String TAG_SUMMONERNAME = "name";
private static final String TAG_SUMMONERLEVEL = "summonerLevel";
private static final String TAG_PROFILEICON = "profileIconId";
long SummonerIdA = 0;
String SummonerNameA = "";
long SummonerLevelA = 0;
int profileIconIdA = 0;
SharedPreferences data4;
public boolean loggedIn = false;
private ProgressDialog pDialog;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login);
Typeface typeFace = Typeface.createFromAsset(getAssets(),"fonts/fq.ttf");
Login = (Button) findViewById(R.id.btnLogin);
Name = (EditText) findViewById(R.id.inputSummonerNameLogin);
one = (TextView) findViewById(R.id.textView1);
two = (TextView) findViewById(R.id.textView2);
Area = (Spinner) findViewById(R.id.spinArea);
Login.setTypeface(typeFace);
one.setTypeface(typeFace);
two.setTypeface(typeFace);
Name.setTypeface(typeFace);
array_spinner= new String[7];
array_spinner[0]="NA";
array_spinner[1]="BR";
array_spinner[2]="EUW";
array_spinner[3]="EUNE";
array_spinner[4]="LAN";
array_spinner[5]="LAS";
array_spinner[6]="OCE";
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item, array_spinner);
Area.setAdapter(adapter);
Area.setOnItemSelectedListener(this);
Login.setOnClickListener(new OnClickListener(){
public void onClick(View V) {
if(Name.getText().length() != 0){
loginName = Name.getText().toString();
url = "https://prod.api.pvp.net/api/lol/" + AreaCode + "/v1.3/summoner/by-name/" + loginName + "?api_key=NOAPIKEYFORYOU";
new GetUserData().execute();
} else{
toastNoNameMethod();
}
}
});
}
private void toastNoNameMethod() {
Toast toastNoName = Toast.makeText(this, "Please Enter a Summoner Name", Toast.LENGTH_SHORT);
toastNoName.show();
}
public void onItemSelected(AdapterView<?> arg0, View arg1, int arg2,
long arg3) {
int i = Area.getSelectedItemPosition();
switch(i){
case 0: AreaCode = "na"; break;
case 1: AreaCode = "br" ; break;
case 2: AreaCode = "euw"; break;
case 3: AreaCode = "eune"; break;
case 4: AreaCode = "lan"; break;
case 5: AreaCode = "las"; break;
case 6: AreaCode = "oce"; break;
}
}
public void onNothingSelected(AdapterView<?> arg0) {
// TODO Auto-generated method stub
}
private class GetUserData extends AsyncTask<Void, Void, Void> {
@Override
protected void onPreExecute() {
super.onPreExecute();
// Showing progress dialog
pDialog = new ProgressDialog(LoginActivity.this);
pDialog.setMessage("Please wait...");
pDialog.setCancelable(false);
pDialog.show();
}
@Override
protected Void doInBackground(Void... arg0) {
// Creating service handler class instance
ServiceHandler sh = new ServiceHandler();
// Making a request to url and getting response
String userDataSummoner = sh.makeServiceCall(url, ServiceHandler.GET);
Log.d("Response: ", "> " + userDataSummoner);
if (userDataSummoner != null) {
try {
JSONObject jsonObj = new JSONObject(userDataSummoner);
JSONObject userData = jsonObj.getJSONObject(loginName);
SummonerIdA = userData.getLong(TAG_SUMMONERID);
SummonerNameA = userData.getString(TAG_SUMMONERNAME);
SummonerLevelA = userData.getLong(TAG_SUMMONERLEVEL);
profileIconIdA = userData.getInt(TAG_PROFILEICON);
} catch (JSONException e) {
e.printStackTrace();
}
} else {
Log.e("ServiceHandler", "Couldn't get any data from the url");
}
return null;
}
@Override
protected void onPostExecute(Void result) {
super.onPostExecute(result);
// Dismiss the progress dialog
if (pDialog.isShowing())
pDialog.dismiss();
Intent myIntent = new Intent(LoginActivity.this, TitleMenu.class);
myIntent.putExtra("SummonerNameTag", SummonerNameA);
myIntent.putExtra("SummonerIdTag", SummonerIdA);
myIntent.putExtra("SummonerLevelTag", SummonerLevelA);
myIntent.putExtra("SummonerProfileIconIdTag", profileIconIdA);
startActivity(myIntent);
loggedIn = true;
SharedPreferences.Editor editor4 = data4.edit();
editor4.putBoolean("LoggedInStatus", loggedIn);
editor4.commit();
finish();
}
}
@Override
public void onBackPressed() {
Intent intent = new Intent(Intent.ACTION_MAIN);
intent.addCategory(Intent.CATEGORY_HOME);
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(intent);
}
}
我的日志猫：
03-21 00:12:16.350: D/AndroidRuntime(31329): Shutting down VM
03-21 00:12:16.350: W/dalvikvm(31329): threadid=1: thread exiting with uncaught exception (group=0x41df9700)
03-21 00:12:16.355: E/AndroidRuntime(31329): FATAL EXCEPTION: main
03-21 00:12:16.355: E/AndroidRuntime(31329): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.chonbonstudios.LOLTOOLs/com.chonbonstudios.LOLTOOLs.TitleMenu}: java.lang.NullPointerException
03-21 00:12:16.355: E/AndroidRuntime(31329): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2308)
03-21 00:12:16.355: E/AndroidRuntime(31329): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2362)
03-21 00:12:16.355: E/AndroidRuntime(31329): at android.app.ActivityThread.access$700(ActivityThread.java:168)
03-21 00:12:16.355: E/AndroidRuntime(31329): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1329)
03-21 00:12:16.355: E/AndroidRuntime(31329): at android.os.Handler.dispatchMessage(Handler.java:99)
03-21 00:12:16.355: E/AndroidRuntime(31329): at android.os.Looper.loop(Looper.java:137)
03-21 00:12:16.355: E/AndroidRuntime(31329): at android.app.ActivityThread.main(ActivityThread.java:5493)
03-21 00:12:16.355: E/AndroidRuntime(31329): at java.lang.reflect.Method.invokeNative(Native Method)
03-21 00:12:16.355: E/AndroidRuntime(31329): at java.lang.reflect.Method.invoke(Method.java:525)
03-21 00:12:16.355: E/AndroidRuntime(31329): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1209)
03-21 00:12:16.355: E/AndroidRuntime(31329): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1025)
03-21 00:12:16.355: E/AndroidRuntime(31329): at dalvik.system.NativeStart.main(Native Method)
03-21 00:12:16.355: E/AndroidRuntime(31329): Caused by: java.lang.NullPointerException
03-21 00:12:16.355: E/AndroidRuntime(31329): at com.chonbonstudios.LOLTOOLs.TitleMenu.onCreate(TitleMenu.java:55)
03-21 00:12:16.355: E/AndroidRuntime(31329): at android.app.Activity.performCreate(Activity.java:5372)
03-21 00:12:16.355: E/AndroidRuntime(31329): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1104)
03-21 00:12:16.355: E/AndroidRuntime(31329): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2270)
03-21 00:12:16.355: E/AndroidRuntime(31329): ... 11 more
03-21 00:12:16.740: D/libEGL(31368): loaded /system/lib/egl/libEGL_mali.so
03-21 00:12:16.740: D/libEGL(31368): loaded /system/lib/egl/libGLESv1_CM_mali.so
03-21 00:12:16.745: D/libEGL(31368): loaded /system/lib/egl/libGLESv2_mali.so
03-21 00:12:16.750: E/(31368): Device driver API match
03-21 00:12:16.750: E/(31368): Device driver API version: 23
03-21 00:12:16.750: E/(31368): User space API version: 23
03-21 00:12:16.750: E/(31368): mali: REVISION=Linux-r3p2-01rel3 BUILD_DATE=Wed Oct 9 21:05:57 KST 2013
03-21 00:12:16.785: D/OpenGLRenderer(31368): Enabling debug mode 0
答案 0 :(得分：0)
在调用data方法之前，您还需要初始化data1，data2，data3和SharedPreferences edit()个实例：
data = getSharedPreferences("pref_key", 0);
SharedPreferences.Editor editor = data.edit();
.....
data1 = getSharedPreferences("pref_key_data1", 0);
SharedPreferences.Editor editor = data1.edit();
.....