android - 必须调用Android requestFeature()，而不是对话框

首先，我很抱歉，这是一篇很长的文章，上面有一段代码墙，但是我想变得更透彻。

单击按钮以在程序中启动此logcat时，我的fragment中出现错误。这说明我必须“在添加内容之前先使用requestFeature（）”。我已经用光了这些论坛上的所有资源。我浏览了关于该主题的所有16篇文章，但这里仅介绍一些内容。

error: requestFeature() must be called before adding content - Still won't work

"android.util.AndroidRuntimeException: requestFeature() must be called before adding content" on showDialog(dialogId)

Dialog problem: requestFeature() must be called before adding content

Error: "requestFeature() must be called before adding content", although it is called before setContentView()

这些解决方案均无效

这些帖子重复出现的主题似乎是dialogs，custom，action等的问题。尝试启动捕获签名的fragment时发生我的错误。相似但不一样。

这是我的代码和logcat。

分段

public class CaptureSignature extends Fragment {

private static final Context Context = null;
View view;
LinearLayout mContent;
signature mSignature;
Button mClear, mGetSign, mCancel;
public static String tempDir;
public int count = 1;
public String current = null;
View mView;
File mypath;

private String uniqueId;
private EditText yourName;

public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {

    this.getActivity().requestWindowFeature(Window.FEATURE_NO_TITLE);

    view = inflater.inflate(R.layout.fragment_signature, container, false);

    mClear = (Button) view.findViewById(R.id.clear);
    mGetSign = (Button) view.findViewById(R.id.getsign);
    mGetSign.setEnabled(false);
    mCancel = (Button) view.findViewById(R.id.cancel);
    yourName = (EditText) view.findViewById(R.id.yourName);

    uniqueId = getTodaysDate() + "_" + getCurrentTime() + "_"
            + Math.random();
    current = uniqueId + ".png";

    mContent = (LinearLayout) view.findViewById(R.id.linearLayout);
    mSignature = new signature(Context, null);
    mSignature.setBackgroundColor(Color.WHITE);
    mContent.addView(mSignature, LayoutParams.MATCH_PARENT,
            LayoutParams.MATCH_PARENT);
    mView = mContent;

    mClear.setOnClickListener(new OnClickListener() {
        public void onClick(View v) {
            Log.v("log_tag", "Panel Cleared");
            mSignature.clear();
            mGetSign.setEnabled(false);
        }
    });

    mGetSign.setOnClickListener(new OnClickListener() {
        public void onClick(View v) {
            Log.v("log_tag", "Panel Saved");
            boolean error = captureSignature();
            if (!error) {
                mView.setDrawingCacheEnabled(true);
            }
        }
    });

    mCancel.setOnClickListener(new OnClickListener() {
        public void onClick(View v) {
            Log.v("log_tag", "Panel Canceled");
        }
    });
    return view;

}

@Override
public void onDestroy() {
    Log.w("GetSignature", "onDestory");
    super.onDestroy();
}

private boolean captureSignature() {

    boolean error = false;
    String errorMessage = "";

    if (yourName.getText().toString().equalsIgnoreCase("")) {
        errorMessage = errorMessage + "Please enter your Name\n";
        error = true;
    }

    if (error) {
        Toast toast = Toast
                .makeText(Context, errorMessage, Toast.LENGTH_SHORT);
        toast.setGravity(Gravity.TOP, 105, 50);
        toast.show();
    }

    return error;
}

private String getTodaysDate() {

    final Calendar c = Calendar.getInstance();
    int todaysDate = (c.get(Calendar.YEAR) * 10000)
            + ((c.get(Calendar.MONTH) + 1) * 100)
            + (c.get(Calendar.DAY_OF_MONTH));
    Log.w("DATE:", String.valueOf(todaysDate));
    return (String.valueOf(todaysDate));

}

private String getCurrentTime() {

    final Calendar c = Calendar.getInstance();
    int currentTime = (c.get(Calendar.HOUR_OF_DAY) * 10000)
            + (c.get(Calendar.MINUTE) * 100) + (c.get(Calendar.SECOND));
    Log.w("TIME:", String.valueOf(currentTime));
    return (String.valueOf(currentTime));

}

public class signature extends View {
    private static final float STROKE_WIDTH = 5f;
    private static final float HALF_STROKE_WIDTH = STROKE_WIDTH / 2;
    private Paint paint = new Paint();
    private Path path = new Path();

    private float lastTouchX;
    private float lastTouchY;
    private final RectF dirtyRect = new RectF();

    public signature(Context captureSignature, AttributeSet attrs) {
        super(captureSignature, attrs);
        paint.setAntiAlias(true);
        paint.setColor(Color.BLACK);
        paint.setStyle(Paint.Style.STROKE);
        paint.setStrokeJoin(Paint.Join.ROUND);
        paint.setStrokeWidth(STROKE_WIDTH);
    }



    public void clear() {
        path.reset();
        invalidate();
    }

    @Override
    protected void onDraw(Canvas canvas) {
        canvas.drawPath(path, paint);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        float eventX = event.getX();
        float eventY = event.getY();
        mGetSign.setEnabled(true);

        switch (event.getAction()) {
        case MotionEvent.ACTION_DOWN:
            path.moveTo(eventX, eventY);
            lastTouchX = eventX;
            lastTouchY = eventY;
            return true;

        case MotionEvent.ACTION_MOVE:

        case MotionEvent.ACTION_UP:

            resetDirtyRect(eventX, eventY);
            int historySize = event.getHistorySize();
            for (int i = 0; i < historySize; i++) {
                float historicalX = event.getHistoricalX(i);
                float historicalY = event.getHistoricalY(i);
                expandDirtyRect(historicalX, historicalY);
                path.lineTo(historicalX, historicalY);
            }
            path.lineTo(eventX, eventY);
            break;

        default:
            debug("Ignored touch event: " + event.toString());
            return false;
        }

        invalidate((int) (dirtyRect.left - HALF_STROKE_WIDTH),
                (int) (dirtyRect.top - HALF_STROKE_WIDTH),
                (int) (dirtyRect.right + HALF_STROKE_WIDTH),
                (int) (dirtyRect.bottom + HALF_STROKE_WIDTH));

        lastTouchX = eventX;
        lastTouchY = eventY;

        return true;
    }

    private void debug(String string) {
    }

    private void expandDirtyRect(float historicalX, float historicalY) {
        if (historicalX < dirtyRect.left) {
            dirtyRect.left = historicalX;
        } else if (historicalX > dirtyRect.right) {
            dirtyRect.right = historicalX;
        }

        if (historicalY < dirtyRect.top) {
            dirtyRect.top = historicalY;
        } else if (historicalY > dirtyRect.bottom) {
            dirtyRect.bottom = historicalY;
        }
    }

    private void resetDirtyRect(float eventX, float eventY) {
        dirtyRect.left = Math.min(lastTouchX, eventX);
        dirtyRect.right = Math.max(lastTouchX, eventX);
        dirtyRect.top = Math.min(lastTouchY, eventY);
        dirtyRect.bottom = Math.max(lastTouchY, eventY);
    }
}
}

主要活动代码

public class Main extends Activity {

TabListener<Store_Fragment> surveyTabListener;
TabListener<Store_Fragment> assetTabListener;
TabListener<Store_Fragment> installTabListener;
TabListener<Store_Fragment> punchTabListener;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    this.requestWindowFeature(Window.FEATURE_NO_TITLE);

    setContentView(R.layout.activity_main);

    // instantiate ActionBar
    ActionBar actionBar = getActionBar();
    //actionBar.setBackgroundDrawable((getResources()
    //.getDrawable(R.drawable.titlebarheader)));
    actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
    actionBar.setTitle("Trakflex");
    actionBar.setDisplayShowTitleEnabled(true);

    // set surveyTab
    Tab surveyTab = actionBar.newTab();
    surveyTabListener = new TabListener<Store_Fragment>(this,
            R.id.header_fragment_container, Store_Fragment.class);
    surveyTab.setText("Survey").setContentDescription("Survey Tab")
            .setTabListener(surveyTabListener);
    actionBar.addTab(surveyTab);

    // set assetTab
    Tab assetTab = actionBar.newTab();
    assetTabListener = new TabListener<Store_Fragment>(this,
            R.id.header_fragment_container, Store_Fragment.class);
    assetTab.setText("Assets").setContentDescription("Assets Tab")
            .setTabListener(assetTabListener);
    actionBar.addTab(assetTab);

    // set installTab
    Tab installTab = actionBar.newTab();
    installTabListener = new TabListener<Store_Fragment>(this,
            R.id.header_fragment_container, Store_Fragment.class);
    installTab.setText("Install Checklist")
            .setContentDescription("Install Checklist Tab")
            .setTabListener(installTabListener);
    actionBar.addTab(installTab);

    // set punchTab
    Tab punchTab = actionBar.newTab();
    punchTabListener = new TabListener<Store_Fragment>(this,
            R.id.header_fragment_container, Store_Fragment.class);
    punchTab.setText("Punchlist").setContentDescription("Punchlist Tab")
            .setTabListener(punchTabListener);
    actionBar.addTab(punchTab);

}

新logcat

05-13 18:57:19.767: E/AndroidRuntime(8950): FATAL EXCEPTION: main
05-13 18:57:19.767: E/AndroidRuntime(8950): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.facilitysolutionsinc.trackflex/com.facilitysolutionsinc.trackflex.Main}: java.lang.NullPointerException
05-13 18:57:19.767: E/AndroidRuntime(8950):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
05-13 18:57:19.767: E/AndroidRuntime(8950):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
05-13 18:57:19.767: E/AndroidRuntime(8950):     at android.app.ActivityThread.access$600(ActivityThread.java:141)
05-13 18:57:19.767: E/AndroidRuntime(8950):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
05-13 18:57:19.767: E/AndroidRuntime(8950):     at android.os.Handler.dispatchMessage(Handler.java:99)
05-13 18:57:19.767: E/AndroidRuntime(8950):     at android.os.Looper.loop(Looper.java:137)
05-13 18:57:19.767: E/AndroidRuntime(8950):     at android.app.ActivityThread.main(ActivityThread.java:5041)
05-13 18:57:19.767: E/AndroidRuntime(8950):     at java.lang.reflect.Method.invokeNative(Native Method)
05-13 18:57:19.767: E/AndroidRuntime(8950):     at java.lang.reflect.Method.invoke(Method.java:511)
05-13 18:57:19.767: E/AndroidRuntime(8950):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
05-13 18:57:19.767: E/AndroidRuntime(8950):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
05-13 18:57:19.767: E/AndroidRuntime(8950):     at dalvik.system.NativeStart.main(Native Method)
05-13 18:57:19.767: E/AndroidRuntime(8950): Caused by: java.lang.NullPointerException
05-13 18:57:19.767: E/AndroidRuntime(8950):     at com.facilitysolutionsinc.trackflex.Main.onCreate(Main.java:32)
05-13 18:57:19.767: E/AndroidRuntime(8950):     at android.app.Activity.performCreate(Activity.java:5104)
05-13 18:57:19.767: E/AndroidRuntime(8950):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
05-13 18:57:19.767: E/AndroidRuntime(8950):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
05-13 18:57:19.767: E/AndroidRuntime(8950):     ... 11 more

如果有人可以帮助我，我将非常感激

最佳答案

您正在从requestWindowFeature()的onCreateView()调用Fragment。这完全为时已晚。如错误所示，requestFeature() must be called before adding content。在这里，“添加内容”是指在您的活动中或运行setContentView()之类的内容，例如，在调用FragmentTransaction的onCreateView()之前都发生了这两种情况。