Java ViewPager nullPointerException错误
我的主要活动Java ViewPager nullPointerException错误,java,android,android-viewpager,Java,Android,Android Viewpager,我的主要活动 package com.std.stunduizmainas; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import java.util.ArrayList; import java.util.List; import org.apache.http.HttpEntity
package com.std.stunduizmainas;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.List;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.ResponseHandler;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.BasicResponseHandler;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicNameValuePair;
import org.json.JSONArray;
import org.json.JSONObject;
import com.std.adapter.SSS;
import com.std.adapter.TabsPagerAdapter;
import com.std.stunduizmainas.R;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.StrictMode;
import android.app.ActionBar;
import android.app.ActionBar.Tab;
import android.app.AlertDialog;
import android.app.Dialog;
import android.app.FragmentTransaction;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.SharedPreferences;
import android.content.DialogInterface.OnCancelListener;
import android.support.v4.app.FragmentActivity;
import android.support.v4.view.ViewPager;
import android.util.Log;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.View.OnTouchListener;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.NumberPicker;
import android.widget.Spinner;
import android.widget.Toast;
import android.widget.AdapterView.OnItemSelectedListener;
public class MainActivity extends FragmentActivity implements ActionBar.TabListener {
public static String izm;
private ViewPager viewPager;
private TabsPagerAdapter mAdapter;
private ActionBar actionBar;
SharedPreferences settings;
Spinner skoluSp;
Spinner klasuSp;
Spinner izvSp;
static String info="";
static String rinfo="";
Dialog fb;
static String sd="";
static String rd="";
List<String> ssk = new ArrayList<String>();
List<String> person = new ArrayList<String>();
List<String> skl = new ArrayList<String>();
List<String> tabi = new ArrayList<String>();
String[] techerorstudent = new String[]{"Skolēns","Skolotājs"};
static String[] tabs = new String[4];
static String regid="";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
StrictMode.enableDefaults();
getActionBar().setTitle("Stundu");
getActionBar().setSubtitle("izmainas");
settings = this.getSharedPreferences("settings", Context.MODE_PRIVATE);
getTab();
startService(new Intent(this,SSS.class));
viewPager = (ViewPager) findViewById(R.id.pager);
actionBar = getActionBar();
mAdapter = new TabsPagerAdapter(getSupportFragmentManager());
viewPager.setAdapter(mAdapter);
actionBar.setHomeButtonEnabled(false);
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
//tabs
for (String tab_name : tabi) {
actionBar.addTab(actionBar.newTab().setText(tab_name)
.setTabListener(this));
}
viewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
@Override
public void onPageSelected(int position) {
actionBar.setSelectedNavigationItem(position);
}
@Override
public void onPageScrolled(int arg0, float arg1, int arg2) {
}
@Override
public void onPageScrollStateChanged(int arg0) {
}
我似乎想不出是什么问题。我知道这是一行代码viewPager.setAdapter(mAdapter)代码>。
日志cat将此显示为错误:
03-04 17:45:48.092: E/AndroidRuntime(1880): FATAL EXCEPTION: main
03-04 17:45:48.092: E/AndroidRuntime(1880): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.std.stunduizmainas/com.std.stunduizmainas.MainActivity}: java.lang.NullPointerException
03-04 17:45:48.092: E/AndroidRuntime(1880): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2211)
03-04 17:45:48.092: E/AndroidRuntime(1880): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2261)
03-04 17:45:48.092: E/AndroidRuntime(1880): at android.app.ActivityThread.access$600(ActivityThread.java:141)
03-04 17:45:48.092: E/AndroidRuntime(1880): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1256)
03-04 17:45:48.092: E/AndroidRuntime(1880): at android.os.Handler.dispatchMessage(Handler.java:99)
03-04 17:45:48.092: E/AndroidRuntime(1880): at android.os.Looper.loop(Looper.java:137)
03-04 17:45:48.092: E/AndroidRuntime(1880): at android.app.ActivityThread.main(ActivityThread.java:5103)
03-04 17:45:48.092: E/AndroidRuntime(1880): at java.lang.reflect.Method.invokeNative(Native Method)
03-04 17:45:48.092: E/AndroidRuntime(1880): at java.lang.reflect.Method.invoke(Method.java:525)
03-04 17:45:48.092: E/AndroidRuntime(1880): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
03-04 17:45:48.092: E/AndroidRuntime(1880): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
03-04 17:45:48.092: E/AndroidRuntime(1880): at dalvik.system.NativeStart.main(Native Method)
03-04 17:45:48.092: E/AndroidRuntime(1880): Caused by: java.lang.NullPointerException
03-04 17:45:48.092: E/AndroidRuntime(1880): at com.std.stunduizmainas.MainActivity.onCreate(MainActivity.java:132)
03-04 17:45:48.092: E/AndroidRuntime(1880): at android.app.Activity.performCreate(Activity.java:5133)
03-04 17:45:48.092: E/AndroidRuntime(1880): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
03-04 17:45:48.092: E/AndroidRuntime(1880): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2175)
03-04 17:45:48.092: E/AndroidRuntime(1880): ... 11 more
有人能帮我吗?看起来你的查看页面是空的
确保此行中使用的ID:
viewPager = (ViewPager) findViewById(R.id.pager);
是有效的,并且引用了activity\u main.xml
layout中的一个viewpager。能否将layout/activity\u main.xml
@TomLeese的内容粘贴到这里:第132行是什么mainActivity@vipulmittalviewPager.setAdapter(mAdapter)
@TomLeese我的id与activity\u main.xml中的id完全相同
viewPager = (ViewPager) findViewById(R.id.pager);