Android 滑动菜单侦听器

在这个项目中，我实现了。为了实现此库，我正在尝试创建一个MenuActivity类，该类处理所有菜单项滑块选项、onClick侦听器等。目前，该类如下所示：

public class MenuActivity extends SlidingActivity{

    SharePrefManager sm = new SharePrefManager(MenuActivity.this);
    RelativeLayout ask_a_question, life_prediction;
    TextView aries,taurus,gemini,cancer,leo,virgo,libra,scorpio,sagittarius,capricon,aquarius,pisces;
    String isLoggedIn; 

    @Override
    public void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setBehindContentView(R.layout.menu);

        ask_a_question = (RelativeLayout)findViewById(R.id.ask_a_question);

        HashMap<String, String> checkLogin = new HashMap<String, String>();
        checkLogin = sm.getuserDetails();
        isLoggedIn = checkLogin.get(SharePrefManager.KEY_ISLOGEDIN);

        ask_a_question.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                if (isLoggedIn.equals(0))
                {
                    Toast.makeText(getApplicationContext(), "You must be logged in", Toast.LENGTH_SHORT).show();
                }

                else
                {
                    Intent i = new Intent("com.example.btshome.ASKPAGE");
                    startActivity(i);
                }

            }
        });


    }


}

在以下实现中，发生以下错误：

04-24 10:46:45.081: E/AndroidRuntime(1956): FATAL EXCEPTION: main
04-24 10:46:45.081: E/AndroidRuntime(1956): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.btshome/com.example.btshome.MainActivity}: java.lang.NullPointerException
04-24 10:46:45.081: E/AndroidRuntime(1956):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1983)
04-24 10:46:45.081: E/AndroidRuntime(1956):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
04-24 10:46:45.081: E/AndroidRuntime(1956):     at android.app.ActivityThread.access$600(ActivityThread.java:130)
04-24 10:46:45.081: E/AndroidRuntime(1956):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
04-24 10:46:45.081: E/AndroidRuntime(1956):     at android.os.Handler.dispatchMessage(Handler.java:99)
04-24 10:46:45.081: E/AndroidRuntime(1956):     at android.os.Looper.loop(Looper.java:137)
04-24 10:46:45.081: E/AndroidRuntime(1956):     at android.app.ActivityThread.main(ActivityThread.java:4745)
04-24 10:46:45.081: E/AndroidRuntime(1956):     at java.lang.reflect.Method.invokeNative(Native Method)
04-24 10:46:45.081: E/AndroidRuntime(1956):     at java.lang.reflect.Method.invoke(Method.java:511)
04-24 10:46:45.081: E/AndroidRuntime(1956):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
04-24 10:46:45.081: E/AndroidRuntime(1956):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
04-24 10:46:45.081: E/AndroidRuntime(1956):     at dalvik.system.NativeStart.main(Native Method)
04-24 10:46:45.081: E/AndroidRuntime(1956): Caused by: java.lang.NullPointerException
04-24 10:46:45.081: E/AndroidRuntime(1956):     at android.content.ContextWrapper.getSharedPreferences(ContextWrapper.java:153)
04-24 10:46:45.081: E/AndroidRuntime(1956):     at com.example.btshome.library.SharePrefManager.<init>(SharePrefManager.java:35)
04-24 10:46:45.081: E/AndroidRuntime(1956):     at com.example.btshome.MenuActivity.<init>(MenuActivity.java:17)
04-24 10:46:45.081: E/AndroidRuntime(1956):     at com.example.btshome.MainActivity.<init>(MainActivity.java:14)
04-24 10:46:45.081: E/AndroidRuntime(1956):     at java.lang.Class.newInstanceImpl(Native Method)
04-24 10:46:45.081: E/AndroidRuntime(1956):     at java.lang.Class.newInstance(Class.java:1319)
04-24 10:46:45.081: E/AndroidRuntime(1956):     at android.app.Instrumentation.newActivity(Instrumentation.java:1053)
04-24 10:46:45.081: E/AndroidRuntime(1956):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1974)
04-24 10:46:45.081: E/AndroidRuntime(1956):     ... 11 more

04-2410:46:45.081:E/AndroidRuntime（1956）：致命异常：main
04-24 10:46:45.081:E/AndroidRuntime（1956）：java.lang.RuntimeException:无法实例化活动组件信息{com.example.btshome/com.example.btshome.MainActivity}:java.lang.NullPointerException
04-24 10:46:45.081:E/AndroidRuntime（1956）：在android.app.ActivityThread.performLaunchActivity（ActivityThread.java:1983）
04-24 10:46:45.081:E/AndroidRuntime（1956）：在android.app.ActivityThread.handleLaunchActivity（ActivityThread.java:2084）
04-24 10:46:45.081:E/AndroidRuntime（1956）：在android.app.ActivityThread.access$600（ActivityThread.java:130）
04-24 10:46:45.081:E/AndroidRuntime（1956）：在android.app.ActivityThread$H.handleMessage（ActivityThread.java:1195）
04-24 10:46:45.081:E/AndroidRuntime（1956）：在android.os.Handler.dispatchMessage（Handler.java:99）上
04-24 10:46:45.081:E/AndroidRuntime（1956）：在android.os.Looper.loop（Looper.java:137）
04-24 10:46:45.081:E/AndroidRuntime（1956）：在android.app.ActivityThread.main（ActivityThread.java:4745）上
04-24 10:46:45.081:E/AndroidRuntime（1956）：位于java.lang.reflect.Method.Invokenactive（本机方法）
04-24 10:46:45.081:E/AndroidRuntime（1956）：位于java.lang.reflect.Method.invoke（Method.java:511）
04-24 10:46:45.081:E/AndroidRuntime（1956）：位于com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run（ZygoteInit.java:786）
04-24 10:46:45.081:E/AndroidRuntime（1956）：在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:553）
04-24 10:46:45.081:E/AndroidRuntime（1956）：在dalvik.system.NativeStart.main（本机方法）
04-24 10:46:45.081:E/AndroidRuntime（1956）：由以下原因引起：java.lang.NullPointerException
04-24 10:46:45.081:E/AndroidRuntime（1956）：在android.content.ContextWrapper.GetSharedReferences（ContextWrapper.java:153）
04-24 10:46:45.081:E/AndroidRuntime（1956）：位于com.example.btshome.library.SharePrefManager。（SharePrefManager.java:35）
04-24 10:46:45.081:E/AndroidRuntime（1956）：位于com.example.btshome.MenuActivity.（MenuActivity.java:17）
04-24 10:46:45.081:E/AndroidRuntime（1956）：位于com.example.btshome.MainActivity。（MainActivity.java:14）
04-24 10:46:45.081:E/AndroidRuntime（1956）：位于java.lang.Class.newInstanceImpl（本机方法）
04-24 10:46:45.081:E/AndroidRuntime（1956）：位于java.lang.Class.newInstance（Class.java:1319）
04-24 10:46:45.081:E/AndroidRuntime（1956）：在android.app.Instrumentation.newActivity（Instrumentation.java:1053）上
04-24 10:46:45.081:E/AndroidRuntime（1956）：在android.app.ActivityThread.performLaunchActivity（ActivityThread.java:1974）
04-24 10:46:45.081:E/AndroidRuntime（1956）：。。。还有11个

---

那么这里出了什么问题？？是活动课吗？我是否以不同的方式处理这个问题

它是在您的

SharePrefManager

的初始化中，特别是

SharePrefManager.java:35

。很可能是使用

null

上下文初始化的

ContextWrapper

。

04-24 10:46:45.081: E/AndroidRuntime(1956): FATAL EXCEPTION: main
04-24 10:46:45.081: E/AndroidRuntime(1956): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.btshome/com.example.btshome.MainActivity}: java.lang.NullPointerException
04-24 10:46:45.081: E/AndroidRuntime(1956):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1983)
04-24 10:46:45.081: E/AndroidRuntime(1956):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
04-24 10:46:45.081: E/AndroidRuntime(1956):     at android.app.ActivityThread.access$600(ActivityThread.java:130)
04-24 10:46:45.081: E/AndroidRuntime(1956):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
04-24 10:46:45.081: E/AndroidRuntime(1956):     at android.os.Handler.dispatchMessage(Handler.java:99)
04-24 10:46:45.081: E/AndroidRuntime(1956):     at android.os.Looper.loop(Looper.java:137)
04-24 10:46:45.081: E/AndroidRuntime(1956):     at android.app.ActivityThread.main(ActivityThread.java:4745)
04-24 10:46:45.081: E/AndroidRuntime(1956):     at java.lang.reflect.Method.invokeNative(Native Method)
04-24 10:46:45.081: E/AndroidRuntime(1956):     at java.lang.reflect.Method.invoke(Method.java:511)
04-24 10:46:45.081: E/AndroidRuntime(1956):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
04-24 10:46:45.081: E/AndroidRuntime(1956):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
04-24 10:46:45.081: E/AndroidRuntime(1956):     at dalvik.system.NativeStart.main(Native Method)
04-24 10:46:45.081: E/AndroidRuntime(1956): Caused by: java.lang.NullPointerException
04-24 10:46:45.081: E/AndroidRuntime(1956):     at android.content.ContextWrapper.getSharedPreferences(ContextWrapper.java:153)
04-24 10:46:45.081: E/AndroidRuntime(1956):     at com.example.btshome.library.SharePrefManager.<init>(SharePrefManager.java:35)
04-24 10:46:45.081: E/AndroidRuntime(1956):     at com.example.btshome.MenuActivity.<init>(MenuActivity.java:17)
04-24 10:46:45.081: E/AndroidRuntime(1956):     at com.example.btshome.MainActivity.<init>(MainActivity.java:14)
04-24 10:46:45.081: E/AndroidRuntime(1956):     at java.lang.Class.newInstanceImpl(Native Method)
04-24 10:46:45.081: E/AndroidRuntime(1956):     at java.lang.Class.newInstance(Class.java:1319)
04-24 10:46:45.081: E/AndroidRuntime(1956):     at android.app.Instrumentation.newActivity(Instrumentation.java:1053)
04-24 10:46:45.081: E/AndroidRuntime(1956):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1974)
04-24 10:46:45.081: E/AndroidRuntime(1956):     ... 11 more