Android 错误：getActivityLogo在包管理器中的何处？

代码： main.xml

这个电话是我的。这意味着您的应用程序清单要求minSdkVersion值至少为9

确保您的AndroidManifest.xml具有与此类似的最小/目标版本-您当前的最小/目标版本可能为8或更低

package com.example.mysecondapp;

import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.ActionBar;
import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.TextView;
import android.os.Build;

public class MainActivity extends ActionBarActivity {

    int counter;
    Button add,sub;
    TextView display;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        if (savedInstanceState == null) {
            getSupportFragmentManager().beginTransaction()
                    .add(R.id.container, new PlaceholderFragment()).commit();       
        }
        display=(TextView) findViewById(R.id.tvdisplay);
        add=(Button) findViewById(R.id.badd);
        sub=(Button) findViewById(R.id.bsub);


         add.setOnClickListener(new View.OnClickListener() {


                public void onClick(View v) {
                    // TODO Auto-generated method stub
                    counter++;
                    display.setText("Your total is" + counter);

                }
         });
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {

        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }

    /**
     * A placeholder fragment containing a simple view.
     */
    public static class PlaceholderFragment extends Fragment {

        public PlaceholderFragment() {
        }

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                Bundle savedInstanceState) {
            View rootView = inflater.inflate(R.layout.fragment_main, container,
                    false);
            return rootView;
        }
    }

}
}

---

哪个支持库？抱歉，我是新来的，所以不太了解，但我打开了PackageManager类，找不到方法检查此链接，这是您在StartingPoint.java中的第36行？？它是buttonHey thanx的onclick方法，但我只是将整个代码和所有库更改为教程中提到的。现在它开始工作了。。因为教程中给出的只有一个xml，而我的项目有两个。。不知道为什么。。我很困惑，因为我是个新手..你在创建时的活动中得到了NullPointerException。没有这些代码，我们就帮不了什么忙。

03-23 16:13:24.390: D/AndroidRuntime(947): Shutting down VM
03-23 16:13:24.390: W/dalvikvm(947): threadid=1: thread exiting with uncaught exception (group=0xb1a9cba8)
03-23 16:13:24.410: E/AndroidRuntime(947): FATAL EXCEPTION: main
03-23 16:13:24.410: E/AndroidRuntime(947): Process: com.example.myfirstapp, PID: 947
03-23 16:13:24.410: E/AndroidRuntime(947): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.myfirstapp/com.example.myfirstapp.StartingPoint}: java.lang.NullPointerException
03-23 16:13:24.410: E/AndroidRuntime(947):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)
03-23 16:13:24.410: E/AndroidRuntime(947):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
03-23 16:13:24.410: E/AndroidRuntime(947):  at android.app.ActivityThread.access$800(ActivityThread.java:135)
03-23 16:13:24.410: E/AndroidRuntime(947):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
03-23 16:13:24.410: E/AndroidRuntime(947):  at android.os.Handler.dispatchMessage(Handler.java:102)
03-23 16:13:24.410: E/AndroidRuntime(947):  at android.os.Looper.loop(Looper.java:136)
03-23 16:13:24.410: E/AndroidRuntime(947):  at android.app.ActivityThread.main(ActivityThread.java:5017)
03-23 16:13:24.410: E/AndroidRuntime(947):  at java.lang.reflect.Method.invokeNative(Native Method)
03-23 16:13:24.410: E/AndroidRuntime(947):  at java.lang.reflect.Method.invoke(Method.java:515)
03-23 16:13:24.410: E/AndroidRuntime(947):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
03-23 16:13:24.410: E/AndroidRuntime(947):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
03-23 16:13:24.410: E/AndroidRuntime(947):  at dalvik.system.NativeStart.main(Native Method)
03-23 16:13:24.410: E/AndroidRuntime(947): Caused by: java.lang.NullPointerException
03-23 16:13:24.410: E/AndroidRuntime(947):  at com.example.myfirstapp.StartingPoint.onCreate(StartingPoint.java:36)
03-23 16:13:24.410: E/AndroidRuntime(947):  at android.app.Activity.performCreate(Activity.java:5231)
03-23 16:13:24.410: E/AndroidRuntime(947):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
03-23 16:13:24.410: E/AndroidRuntime(947):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)
03-23 16:13:24.410: E/AndroidRuntime(947):  ... 11 more
03-23 16:13:33.790: I/Process(947): Sending signal. PID: 947 SIG: 9
03-23 16:18:06.983: D/AndroidRuntime(1155): Shutting down VM
03-23 16:18:06.983: W/dalvikvm(1155): threadid=1: thread exiting with uncaught exception (group=0xb1a9cba8)
03-23 16:18:07.003: E/AndroidRuntime(1155): FATAL EXCEPTION: main
03-23 16:18:07.003: E/AndroidRuntime(1155): Process: com.example.myfirstapp, PID: 1155
03-23 16:18:07.003: E/AndroidRuntime(1155): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.myfirstapp/com.example.myfirstapp.StartingPoint}: java.lang.NullPointerException
03-23 16:18:07.003: E/AndroidRuntime(1155):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)
03-23 16:18:07.003: E/AndroidRuntime(1155):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
03-23 16:18:07.003: E/AndroidRuntime(1155):     at android.app.ActivityThread.access$800(ActivityThread.java:135)
03-23 16:18:07.003: E/AndroidRuntime(1155):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
03-23 16:18:07.003: E/AndroidRuntime(1155):     at android.os.Handler.dispatchMessage(Handler.java:102)
03-23 16:18:07.003: E/AndroidRuntime(1155):     at android.os.Looper.loop(Looper.java:136)
03-23 16:18:07.003: E/AndroidRuntime(1155):     at android.app.ActivityThread.main(ActivityThread.java:5017)
03-23 16:18:07.003: E/AndroidRuntime(1155):     at java.lang.reflect.Method.invokeNative(Native Method)
03-23 16:18:07.003: E/AndroidRuntime(1155):     at java.lang.reflect.Method.invoke(Method.java:515)
03-23 16:18:07.003: E/AndroidRuntime(1155):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
03-23 16:18:07.003: E/AndroidRuntime(1155):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
03-23 16:18:07.003: E/AndroidRuntime(1155):     at dalvik.system.NativeStart.main(Native Method)
03-23 16:18:07.003: E/AndroidRuntime(1155): Caused by: java.lang.NullPointerException
03-23 16:18:07.003: E/AndroidRuntime(1155):     at com.example.myfirstapp.StartingPoint.onCreate(StartingPoint.java:36)
03-23 16:18:07.003: E/AndroidRuntime(1155):     at android.app.Activity.performCreate(Activity.java:5231)
03-23 16:18:07.003: E/AndroidRuntime(1155):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
03-23 16:18:07.003: E/AndroidRuntime(1155):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)
03-23 16:18:07.003: E/AndroidRuntime(1155):     ... 11 more
03-23 16:23:07.463: I/Process(1155): Sending signal. PID: 1155 SIG: 9

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent">
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Your total is:"
        android:id="@+id/tvdisplay"
         />
     <Button
        android:layout_width="250dp"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:text="Add one"        
        android:textSize="40sp"
        android:id="@+id/badd"
         />
      <Button
        android:layout_width="250dp"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:text="Subtract one"        
        android:textSize="40sp"
        android:id="@+id/bsub" 
        />
</LinearLayout>

package com.example.mysecondapp;

import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.ActionBar;
import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.TextView;
import android.os.Build;

public class MainActivity extends ActionBarActivity {

    int counter;
    Button add,sub;
    TextView display;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        if (savedInstanceState == null) {
            getSupportFragmentManager().beginTransaction()
                    .add(R.id.container, new PlaceholderFragment()).commit();       
        }
        display=(TextView) findViewById(R.id.tvdisplay);
        add=(Button) findViewById(R.id.badd);
        sub=(Button) findViewById(R.id.bsub);


         add.setOnClickListener(new View.OnClickListener() {


                public void onClick(View v) {
                    // TODO Auto-generated method stub
                    counter++;
                    display.setText("Your total is" + counter);

                }
         });
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {

        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }

    /**
     * A placeholder fragment containing a simple view.
     */
    public static class PlaceholderFragment extends Fragment {

        public PlaceholderFragment() {
        }

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                Bundle savedInstanceState) {
            View rootView = inflater.inflate(R.layout.fragment_main, container,
                    false);
            return rootView;
        }
    }

}
}

<uses-sdk
    android:minSdkVersion="9"
    android:targetSdkVersion="19" />