如何从警报对话框中的按钮开始新活动?

Question

在这个应用程序中，我创建了扫描仪，结果将以alertDialog显示，带有两个按钮;OK和NEXT.NEXT按钮，我想转到新活动。问题是，当单击"下一步"按钮时，它会崩溃。

请帮助我..
我是新来的。

@Override
public void handleResult(final Result result) {
AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setTitle("Scan Result");
builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialogInterface, int i) {
scannerView.resumeCameraPreview(qrscanner.this);
}
});
builder.setNeutralButton("NEXT", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialogInterface, int i) {
Intent intent = new Intent(qrscanner.this,attend_form.class);
startActivity(intent);
}
});
AlertDialog alert = builder.create();
alert.show();

这个attend_form

public class attend_form extends AppCompatActivity {
Toolbar toolbar;
Button btn_get_sign, mClear, mGetSign, mCancel, btn_rega;
RadioGroup battend;
EditText File,Ic;
String file_number,ic_no;
String attendance = "";
AlertDialog.Builder builder;
String url_reg = "http://192.168.1.7/spm/android/attendance/attend.php";
File file;
Dialog dialog;
LinearLayout mContent;
View view;
signature mSignature;
Bitmap bitmap;
// Creating Separate Directory for saving Generated Images
String DIRECTORY = Environment.getExternalStorageDirectory().getPath() + "/DigitSign/";
String pic_name = new SimpleDateFormat("yyyyMMdd_HHmmss", Locale.getDefault()).format(new Date());
String StoredPath = DIRECTORY + pic_name + ".png";

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_attend_form);
this.setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
// Setting ToolBar as ActionBar
toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
btn_rega = (Button)findViewById(R.id.btn_rega);
final RadioGroup battend = (RadioGroup)findViewById(R.id.attendance);
final RadioButton attend = (RadioButton)findViewById(R.id.btn_attend);
final RadioButton absent = (RadioButton)findViewById(R.id.btn_absent);
// Button to open signature panel
btn_get_sign = (Button) findViewById(R.id.signature);
File = (EditText)findViewById(R.id.file_number);
Ic = (EditText)findViewById(R.id.ic_no);
builder = new AlertDialog.Builder(attend_form.this);

btn_rega.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
file_number = File.getText().toString();
ic_no = Ic.getText().toString();
if (battend.getCheckedRadioButtonId() == attend.getId())
{
attendance = "ATTEND";
}
else if(battend.getCheckedRadioButtonId() == absent.getId())
{
attendance = "ABSENT";
}

if(file_number.equals("") || ic_no.equals(""))
{
builder.setTitle("Something were wrong");
builder.setMessage("Please fill all field");
displayAlert("input_error");
}
else
{
StringRequest stringRequest = new StringRequest(Request.Method.POST, url_reg, new Response.Listener<String>() {
@Override
public void onResponse(String response) {
try {
JSONArray jsonArray = new JSONArray(response);
JSONObject jsonObject = jsonArray.getJSONObject(0);
String code = jsonObject.getString("code");
String message = jsonObject.getString("message");
builder.setTitle("Server Response");
builder.setMessage(message);
displayAlert(code);
}catch (JSONException e)
{
e.printStackTrace();
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
}
}){
@SuppressWarnings("deprecation")
@Override
protected Map<String, String> getPostParams() throws AuthFailureError {
Map<String,String> params = new HashMap<String, String>();
params.put("file_number",file_number);
params.put("ic_no",ic_no);
params.put("attendance",attendance);
return super.getPostParams();
}
@Override
protected Map<String, String> getParams() throws AuthFailureError {
Map<String,String> params = new HashMap<String, String>();
params.put("file_number",file_number);
params.put("ic_no",ic_no);
params.put("attendance",attendance);
return params;
}
};
MySingleton.getInstance(attend_form.this).addToRequestque(stringRequest);
}
}
});

// Method to create Directory, if the Directory doesn't exists
file = new File(DIRECTORY);
if (!file.exists()) {
file.mkdir();
}
// Dialog Function
dialog = new Dialog(attend_form.this);
// Removing the features of Normal Dialogs
dialog.requestWindowFeature(Window.FEATURE_NO_TITLE);
dialog.setContentView(R.layout.dialog_signature);
dialog.setCancelable(true);

btn_get_sign.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// Function call for Digital Signature
dialog_action();
}
});
}
public void displayAlert(final String code)
{
builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialogInterface, int which) {
if(code.equals("input_error"))
{
File.setText("");
Ic.setText("");
}
else if(code.equals("reg_success"))
{
finish();
}
else if(code.equals("reg_failed"))
{
File.setText("");
Ic.setText("");
}
}
});
AlertDialog alertDialog = builder.create();
alertDialog.show();
}

// Function for Digital Signature
public void dialog_action() {
mContent = (LinearLayout) dialog.findViewById(R.id.linearLayout);
mSignature = new signature(getApplicationContext(), null);
mSignature.setBackgroundColor(Color.WHITE);
// Dynamically generating Layout through java code
mContent.addView(mSignature, ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT);
mClear = (Button) dialog.findViewById(R.id.clear);
mGetSign = (Button) dialog.findViewById(R.id.getsign);
mGetSign.setEnabled(false);
mCancel = (Button) dialog.findViewById(R.id.cancel);
view = mContent;
mClear.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
Log.v("log_tag", "Panel Cleared");
mSignature.clear();
mGetSign.setEnabled(false);
}
});
mGetSign.setOnClickListener(new View.OnClickListener() {
@SuppressWarnings("deprecation")
public void onClick(View v) {
Log.v("log_tag", "Panel Saved");
view.setDrawingCacheEnabled(true);
mSignature.save(view, StoredPath);
dialog.dismiss();
Toast.makeText(getApplicationContext(), "Successfully Saved", Toast.LENGTH_SHORT).show();
// Calling the same class
recreate();
}
});
mCancel.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
Log.v("log_tag", "Panel Canceled");
dialog.dismiss();
// Calling the same class
recreate();
}
});
dialog.show();
}

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 context, AttributeSet attrs) {
super(context, attrs);
paint.setAntiAlias(true);
paint.setColor(Color.BLACK);
paint.setStyle(Paint.Style.STROKE);
paint.setStrokeJoin(Paint.Join.ROUND);
paint.setStrokeWidth(STROKE_WIDTH);
}
public void save(View v, String StoredPath) {
Log.v("log_tag", "Width: " + v.getWidth());
Log.v("log_tag", "Height: " + v.getHeight());
if (bitmap == null) {
bitmap = Bitmap.createBitmap(mContent.getWidth(), mContent.getHeight(), Bitmap.Config.RGB_565);
}
Canvas canvas = new Canvas(bitmap);
try {
// Output the file
FileOutputStream mFileOutStream = new FileOutputStream(StoredPath);
v.draw(canvas);
// Convert the output file to Image such as .png
bitmap.compress(Bitmap.CompressFormat.PNG, 90, mFileOutStream);
mFileOutStream.flush();
mFileOutStream.close();
} catch (Exception e) {
Log.v("log_tag", e.toString());
}
}
public void clear() {
path.reset();
invalidate();
}
@Override
protected void onDraw(Canvas canvas) {
canvas.drawPath(path, paint);
}
@SuppressWarnings("deprecation")
@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) {
Log.v("log_tag", 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);
}
}
}

字符串请求类

public class StringRequestClass extends AsyncTask<String, Void, String> {

//Your task happens here
EditText File,Ic;
String file_number,ic_no;
String attendance = "";
AlertDialog.Builder builder;
String url_reg = "http://192.168.1.7/spm/android/attendance/attend.php";
@Override
protected String doInBackground(String... params) {
//Do your StringRequest here.


if(file_number.equals("") || ic_no.equals(""))
{
builder.setTitle("Something were wrong");
builder.setMessage("Please fill all field");
displayAlert("input_error");
}
return null;
}
//Things to do when your task is complete.
@Override
protected void onPostExecute(String result) {
//Do everything you want to do after the StringRequest is completed.
StringRequest stringRequest = new StringRequest(Request.Method.POST, url_reg, new Response.Listener<String>() {
@Override
public void onResponse(String response) {
try {
JSONArray jsonArray = new JSONArray(response);
JSONObject jsonObject = jsonArray.getJSONObject(0);
String code = jsonObject.getString("code");
String message = jsonObject.getString("message");
builder.setTitle("Server Response");
builder.setMessage(message);
displayAlert(code);
}catch (JSONException e)
{
e.printStackTrace();
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
}
}){

@Override
protected Map<String, String> getParams() throws AuthFailureError {
Map<String,String> params = new HashMap<String, String>();
params.put("file_number",file_number);
params.put("ic_no",ic_no);
params.put("attendance",attendance);
return params;
}
};
MySingleton.getInstance(attend_form.this).addToRequestque(stringRequest);
}
@Override
protected void onPreExecute() {
super.onPreExecute();
if(file_number.equals("") || ic_no.equals(""))
{
builder.setTitle("Something were wrong");
builder.setMessage("Please fill all field");
displayAlert("input_error");
}
} //Things to do before the internet-related task
@Override
protected void onProgressUpdate(Void... values) {}

public void displayAlert(final String code)
{
builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialogInterface, int which) {
if(code.equals("input_error"))
{
File.setText("");
Ic.setText("");
}
else if(code.equals("reg_success"))
{
finish();
}
else if(code.equals("reg_failed"))
{
File.setText("");
Ic.setText("");
}
}
});
AlertDialog alertDialog = builder.create();
alertDialog.show();
}
}

Answer 1

尝试使用getContext()

Intent intent = new Intent(getContext(), attend_form.class);
getContext().startActivity(intent);