嗨，我遵循了一个教程，我试图在android中测试滑动菜单（导航抽屉），但是我在logcat中不断遇到这些错误。请帮助我或给我一些想法，以便我可以继续解决该问题。帮助......。
2-12 18:37:43.976: E/Trace(698): error opening trace file: No such file or directory (2)
02-12 18:37:44.666: I/System.out(698): activity started-----------
02-12 18:37:44.666: I/System.out(698): 3
02-12 18:37:44.676: D/AndroidRuntime(698): Shutting down VM
02-12 18:37:44.676: W/dalvikvm(698): threadid=1: thread exiting with uncaught exception (group=0x40a13300)
02-12 18:37:44.696: E/AndroidRuntime(698): FATAL EXCEPTION: main
02-12 18:37:44.696: E/AndroidRuntime(698): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.navigationdrawertest/com.example.navigationdrawertest.HomeActivity}: java.lang.NullPointerException
02-12 18:37:44.696: E/AndroidRuntime(698): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2059)
02-12 18:37:44.696: E/AndroidRuntime(698): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
02-12 18:37:44.696: E/AndroidRuntime(698): at android.app.ActivityThread.access$600(ActivityThread.java:130)
02-12 18:37:44.696: E/AndroidRuntime(698): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
02-12 18:37:44.696: E/AndroidRuntime(698): at android.os.Handler.dispatchMessage(Handler.java:99)
02-12 18:37:44.696: E/AndroidRuntime(698): at android.os.Looper.loop(Looper.java:137)
02-12 18:37:44.696: E/AndroidRuntime(698): at android.app.ActivityThread.main(ActivityThread.java:4745)
02-12 18:37:44.696: E/AndroidRuntime(698): at java.lang.reflect.Method.invokeNative(Native Method)
02-12 18:37:44.696: E/AndroidRuntime(698): at java.lang.reflect.Method.invoke(Method.java:511)
02-12 18:37:44.696: E/AndroidRuntime(698): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
02-12 18:37:44.696: E/AndroidRuntime(698): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
02-12 18:37:44.696: E/AndroidRuntime(698): at dalvik.system.NativeStart.main(Native Method)
02-12 18:37:44.696: E/AndroidRuntime(698): Caused by: java.lang.NullPointerException
02-12 18:37:44.696: E/AndroidRuntime(698): at com.example.navigationdrawertest.HomeActivity.onCreate(HomeActivity.java:40)
02-12 18:37:44.696: E/AndroidRuntime(698): at android.app.Activity.performCreate(Activity.java:5008)
02-12 18:37:44.696: E/AndroidRuntime(698): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079)
02-12 18:37:44.696: E/AndroidRuntime(698): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2023)
02-12 18:37:44.696: E/AndroidRuntime(698): ... 11 more
02-12 18:37:48.396: I/Process(698): Sending signal. PID: 698 SIG: 9
还有我的HomeActivity.java文件
package com.example.navigationdrawertest;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.app.Fragment;
import android.app.FragmentManager;
import android.content.res.Configuration;
import android.os.Bundle;
import android.support.v4.app.ActionBarDrawerToggle;
import android.support.v4.widget.DrawerLayout;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;
import com.example.navigationdrawertest.operatingsystemfragment.*;
public class HomeActivity extends Activity {
private String[] mPlanetTitles;
private DrawerLayout mDrawerLayout;
private ListView mDrawerList;
private ActionBarDrawerToggle mDrawerToggle;
private CharSequence title;
@SuppressLint("NewApi")
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_home);
System.out.println("activity started-----------");
title = getActionBar().getTitle();
mPlanetTitles = getResources().getStringArray(R.array.operating_systems);
System.out.println(mPlanetTitles.length);
mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
mDrawerList = (ListView) findViewById(R.id.left_drawer);
// Set the adapter for the list view
mDrawerList.setAdapter(new ArrayAdapter<String>(this,
R.layout.nav_drawer,R.id.content_frame, mPlanetTitles));
System.out.println("adapater set to list");
// Set the list's click listener
mDrawerList.setOnItemClickListener(new DrawerItemClickListener());
mDrawerToggle = new ActionBarDrawerToggle(this, /* host Activity */
mDrawerLayout, /* DrawerLayout object */
R.drawable.ic_drawer, /* nav drawer icon to replace 'Up' caret */
R.string.drawer_open, /* "open drawer" description */
R.string.drawer_close /* "close drawer" description */) {
/** Called when a drawer has settled in a completely closed state. */
public void onDrawerClosed(View view) {
getActionBar().setTitle(title);
}
/** Called when a drawer has settled in a completely open state. */
public void onDrawerOpened(View drawerView) {
getActionBar().setTitle("Open Drawer");
}
};
// Set the drawer toggle as the DrawerListener and then Drawer layout will listen on Drawertoggle
mDrawerLayout.setDrawerListener(mDrawerToggle);
getActionBar().setDisplayHomeAsUpEnabled(true);
getActionBar().setHomeButtonEnabled(true);
System.out.println("on create method completed");
}
private class DrawerItemClickListener implements ListView.OnItemClickListener {
@Override
public void onItemClick(AdapterView parent, View view, int position, long id) {
System.out.println("DrawerItemClickListener");
selectItem(position);
}
}
@Override
protected void onPostCreate(Bundle savedInstanceState) {
super.onPostCreate(savedInstanceState);
// Sync the toggle state after onRestoreInstanceState has occurred.
mDrawerToggle.syncState();
}
@Override
public void onConfigurationChanged(Configuration newConfig) {
super.onConfigurationChanged(newConfig);
mDrawerToggle.onConfigurationChanged(newConfig);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.home, menu);
return super.onCreateOptionsMenu(menu);
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Pass the event to ActionBarDrawerToggle, if it returns
// true, then it has handled the app icon touch event
if (mDrawerToggle.onOptionsItemSelected(item)) {
return true;
}
// Handle your other action bar items...
switch (item.getItemId()) {
case R.id.action_settings:
Toast.makeText(this, "Settings selected", Toast.LENGTH_LONG).show();
break;
default:
break;
}
return super.onOptionsItemSelected(item);
}
/** Swaps fragments in the main content view */
private void selectItem(int position) {
System.out.println("selectItem called");
// create a new fragment and specify the planet to show based on position
Fragment fragment = new OperatingSystemFragment();
Bundle args = new Bundle();
args.putInt(OperatingSystemFragment.ARG_OS, position);
fragment.setArguments(args);
// Insert the fragment by replacing any existing fragment
FragmentManager fragmentManager = getFragmentManager();
fragmentManager.beginTransaction()
.replace(R.id.content_frame, fragment)
.commit();
// Highlight the selected item, update the title, and close the drawer
mDrawerList.setItemChecked(position, true);
getActionBar().setTitle((mPlanetTitles[position]));
mDrawerLayout.closeDrawer(mDrawerList);
}
}
我必须在API 8中使用导航抽屉，因此要使用支持包。请帮我。
最佳答案
您的mDrawerList为null或mPlanetTitles为null。在调试器上同时检查它们。
关于java - 构建测试滑动菜单时出错，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/21729640/