0

flash（）を呼び出すと、nullポインター例外が発生します。より正確には、アプリケーションを開き（正しく機能し、強制的に閉じることはありません）、メニューボタンを押して設定を選択し（ActivitySettingsを開始）、戻ると表示されます。 nullポインタ例外。

PS（logcatで読んだので、問題がflash（）であることはわかっています）

public class MainActivity extends Activity {
    private boolean isFlashOn = false;
    private Camera camera;
    public ImageButton imagebutton;
    String r,t;
    String scelta="btn0";
    @Override
    public void onCreate(Bundle savedInstanceState) {
        t=CheckPrefsThm();
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        ChooseThm();
        r = CheckPrefsImg();
        super.onCreate(savedInstanceState);
        Decision();
        camera = Camera.open();
    }

    @Override
    public void onStart() {
        super.onStart();
        imagebutton.setOnClickListener(new OnClickListener() {
            public void onClick(View w) {

                flash();

            }
        });
    }

    public void flash() {
        final Parameters p = camera.getParameters();
        if(isFlashOn) {
            p.setFlashMode(Parameters.FLASH_MODE_OFF);
            camera.setParameters(p);
            isFlashOn = false;
            if(scelta.equals("btn1")) {
                imagebutton.setImageResource(R.drawable.powerg);
            }
            if(scelta.equals("btn0")) {
                imagebutton.setImageResource(R.drawable.traoff);
            }
            if(scelta.equals("btn2")) {
                imagebutton.setImageResource(R.drawable.pushg);
            }   
            if(scelta.equals("btn3")) {
                imagebutton.setImageResource(R.drawable.playg1);
            }
            if(scelta.equals("btn4")) {
                imagebutton.setImageResource(R.drawable.playg2);
            }
        }
        else {
            p.setFlashMode(Parameters.FLASH_MODE_TORCH);
            camera.setParameters(p);
            isFlashOn = true;  
            if(scelta.equals("btn1")) {
                imagebutton.setImageResource(R.drawable.powerg);
            }
            if(scelta.equals("btn0")) {
                imagebutton.setImageResource(R.drawable.traon);
            }
            if(scelta.equals("btn2")) {
                imagebutton.setImageResource(R.drawable.pushgon);
            }
            if(scelta.equals("btn3")) {
                imagebutton.setImageResource(R.drawable.playg1);
            }
            if(scelta.equals("btn4")) {
                imagebutton.setImageResource(R.drawable.playg2);
            }
        }
    }

    @Override
    protected void onStop() {
        super.onStop();
        if (camera != null) {
            camera.release();
            finish();
        }
    }

    @Override
    public void onResume() {
        super.onResume();
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.preferences, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        Intent startNewActivityOpen = new Intent(this, SettingsActivity.class);     
        switch(item.getItemId()) {
            case R.id.menu_settings:
                UpdatePrefs(r ,t);
                startActivityForResult(startNewActivityOpen,0);                 
                return true;
            default:
                return super.onOptionsItemSelected(item);
        }
    }

    public String CheckPrefsImg() {
        SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(this);
        String result = prefs.getString("img","uno");

        return result;
    }

    public String CheckPrefsThm() { 
        SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(this);
        String result = prefs.getString("thm","dark");

        return result;
    }

    public void UpdatePrefs(String img,String thm) {
        SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(this);
        SharedPreferences.Editor editor = prefs.edit();
        editor.putString("img",img);
        editor.putString("thm",thm);
        editor.commit();
    }

    public void ChooseThm() {
        if(t.equals("radiolight")) {
            this.setTheme(R.style.Light);
        }
        else{
            if(t.equals("radiodark")) {
                this.setTheme(R.style.Dark);
            }
        }
    }

    public void Decision() {
        if(r.equals("uno") ) {
            setContentView(R.layout.activity_main);
            imagebutton = (ImageButton)findViewById(R.id.torcia);
            scelta="btn0";
        }
        else if(r.equals("due")) {
            setContentView(R.layout.activity_main2);
            imagebutton = (ImageButton)findViewById(R.id.btn1);
            scelta="btn1";
        }
        else if(r.equals("tre")) {
            setContentView(R.layout.activity_main3);
            imagebutton = (ImageButton)findViewById(R.id.btn2);
            scelta="btn2";
        }
        else if(r.equals("quattro")) {
            setContentView(R.layout.activity_main4);
            imagebutton = (ImageButton)findViewById(R.id.btn3);
            scelta="btn3";
        }
        else if(r.equals("cinque")) {
            setContentView(R.layout.activity_main5);
            imagebutton = (ImageButton)findViewById(R.id.btn4);
            scelta="btn4";
        }
    }  
}

編集：これが私のlogcatです

03-16 13:47:21.174: D/dalvikvm(29612): Late-enabling CheckJNI
03-16 13:47:21.204: E/jdwp(29612): Failed sending reply to debugger: Broken pipe
03-16 13:47:21.204: D/dalvikvm(29612): Debugger has detached; object registry had   1 entries
03-16 13:47:21.404: D/dalvikvm(29612): GC_FOR_ALLOC freed 111K, 6% free 12166K/     12931K, paused 33ms, total 33ms
03-16 13:47:21.404: I/dalvikvm-heap(29612): Grow heap (frag case) to 12.899MB for   484456-byte allocation
03-16 13:47:21.449: D/dalvikvm(29612): GC_CONCURRENT freed 1K, 7% free 12638K/      13447K, paused 19ms+1ms, total 45ms
03-16 13:47:22.429: D/libEGL(29612): loaded /system/lib/egl/libEGL_mali.so
03-16 13:47:22.434: D/libEGL(29612): loaded /system/lib/egl/libGLESv1_CM_mali.so
03-16 13:47:22.439: D/libEGL(29612): loaded /system/lib/egl/libGLESv2_mali.so
03-16 13:47:22.444: D/(29612): Device driver API match
03-16 13:47:22.444: D/(29612): Device driver API version: 10
03-16 13:47:22.444: D/(29612): User space API version: 10 
03-16 13:47:22.444: D/(29612): mali: REVISION=Linux-r2p4-02rel0 BUILD_DATE=Tue Oct  16 15:37:13 KST 2012 
03-16 13:47:22.579: D/OpenGLRenderer(29612): Enabling debug mode 0
03-16 13:47:29.734: W/Camera(29612): Camera server died!
03-16 13:47:44.749: D/AbsListView(29612): Get MotionRecognitionManager
03-16 13:47:45.444: D/dalvikvm(29612): GC_CONCURRENT freed 108K, 6% free 12965K/    13703K, paused 12ms+2ms, total 25ms
03-16 13:47:45.474: E/SensorManager(29612): thread start
03-16 13:47:45.474: D/SensorManager(29612): registerListener::handle=0name=LSM330DLC 3-axis Accelerometer delay= 200000Listener=android.view.
OrientationEventListener$SensorEventListenerImpl@41e66718
03-16 13:47:45.554: E/SpannableStringBuilder(29612): SPAN_EXCLUSIVE_EXCLUSIVE       spans cannot have a zero length
03-16 13:47:45.554: E/SpannableStringBuilder(29612): SPAN_EXCLUSIVE_EXCLUSIVE       spans cannot have a zero length
03-16 13:47:51.909: D/SensorManager(29612): unregisterListener::  Listener=android.view.OrientationEventListener

$SensorEventListenerImpl@41e66718
03-16 13:47:51.909: D/Sensors(29612): Remain listener = Sending .. normal delay     200ms
03-16 13:47:51.909: I/Sensors(29612): sendDelay --- 200000000
03-16 13:47:51.909: D/SensorManager(29612): JNI - sendDelay
03-16 13:47:51.909: I/SensorManager(29612): Set normal delay = true
03-16 13:47:53.319: W/Camera(29612): Camera server died!
03-16 13:47:53.329: I/Choreographer(29612): Skipped 84 frames!  The application may be doing too much work on its main thread.
03-16 13:47:53.409: E/SpannableStringBuilder(29612): SPAN_EXCLUSIVE_EXCLUSIVE spans cannot have a zero length
03-16 13:47:53.409: E/SpannableStringBuilder(29612): SPAN_EXCLUSIVE_EXCLUSIVE spans cannot have a zero length
03-16 13:48:01.899: D/AndroidRuntime(29612): Shutting down VM
03-16 13:48:01.899: W/dalvikvm(29612): threadid=1: thread exiting with uncaught exception (group=0x411542a0)
03-16 13:48:01.904: E/AndroidRuntime(29612): FATAL EXCEPTION: main
03-16 13:48:01.904: E/AndroidRuntime(29612): java.lang.NullPointerException
03-16 13:48:01.904: E/AndroidRuntime(29612):    at com.burattiluca.latorcia.MainActivity.flash(MainActivity.java:47)
03-16 13:48:01.904: E/AndroidRuntime(29612):    at com.burattiluca.latorcia.MainActivity$1.onClick(MainActivity.java:41)
03-16 13:48:01.904: E/AndroidRuntime(29612):    at android.view.View.performClick(View.java:4211)
03-16 13:48:01.904: E/AndroidRuntime(29612):    at android.view.View$PerformClick.run(View.java:17267)
03-16 13:48:01.904: E/AndroidRuntime(29612):    at android.os.Handler.handleCallback(Handler.java:615)
03-16 13:48:01.904: E/AndroidRuntime(29612):    at android.os.Handler.dispatchMessage(Handler.java:92)
03-16 13:48:01.904: E/AndroidRuntime(29612):    at android.os.Looper.loop(Looper.java:137)
03-16 13:48:01.904: E/AndroidRuntime(29612):    at android.app.ActivityThread.main(ActivityThread.java:4898)
03-16 13:48:01.904: E/AndroidRuntime(29612):    at java.lang.reflect.Method.invokeNative(Native Method)
03-16 13:48:01.904: E/AndroidRuntime(29612):    at java.lang.reflect.Method.invoke(Method.java:511)
03-16 13:48:01.904: E/AndroidRuntime(29612):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:773)
03-16 13:48:01.904: E/AndroidRuntime(29612):    at dalvik.system.NativeStart.main(Native Method)
4

4 に答える 4

0

次のコードに変更して、機能するかどうかを確認してください 

 @Override
public boolean onOptionsItemSelected(MenuItem item) {
// remove onClickListener    
imagebutton.setOnClickListener(null);
Intent startNewActivityOpen = new Intent(this, SettingsActivity.class);     
switch(item.getItemId()){
    case R.id.menu_settings:
            UpdatePrefs(r ,t);
            startActivityForResult(startNewActivityOpen,0);                 
            return true;
    default:
        return super.onOptionsItemSelected(item);
}

}

次にonActivityResult 

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent intent)
{
    super.onActivityResult(requestCode, resultCode, intent);
    imagebutton.setOnClickListener(new OnClickListener(){
    public void onClick(View w){

    flash();

    }
});
}
于 2013-03-18T21:46:29.293 に答える
0

onCreate（）でsetcontentview（）を使用していません...nullpointerexceptionを生成していると思います...詳細についてはlogcat出力を入力してください

于 2013-03-16T19:31:53.193 に答える
0

Camera.open()デバイスに背面カメラがない場合はnullを返すため、カメラはnullになっていると思います。

androidドキュメントを読んでください。

これをデバイスでテストし、このコードをcatchブロックに入れて、アプリケーションタグの上にあるカメラにアクセスするために必要なすべての権限が追加されていることを確認してください。

于 2013-03-16T19:33:15.603 に答える