我有一个活动，用户将使用 GestureOverlayView 进行签名。提供签名后，图像将保存在应用程序的内存中，并且引用（图像名称）和其他详细信息将包含在 SQLite 表中。
这是布局文件：
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#142c57"
android:padding="3dp"
tools:context=".SupplierCustomerDetailsSignatureActivity" >
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<RelativeLayout
android:layout_width="fill_parent"
android:layout_height="0dp"
android:layout_weight="3" >
<ScrollView
android:id="@+id/scrollView1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_gravity="center" >
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:descendantFocusability="beforeDescendants"
android:focusableInTouchMode="true" >
<RelativeLayout
android:id="@+id/layout_1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:background="@drawable/btn_blue" >
<TextView
android:id="@+id/customer_name_textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:text="TextView"
android:textColor="#FFFFFF"
android:textSize="22sp" />
</RelativeLayout>
<TableLayout
android:id="@+id/table"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/layout_1"
android:layout_centerHorizontal="true"
android:stretchColumns="0,1" >
<TableRow
android:id="@+id/tableRow1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="10dp">
<TextView
android:id="@+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="DD Details: "
android:textColor="#FFFFFF"
android:textSize="18sp" />
<TextView
android:id="@+id/dd_details_textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="TextView"
android:textColor="#FFFFFF"
android:textSize="18sp" />
</TableRow>
<TableRow
android:id="@+id/tableRow2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="10dp">
<TextView
android:id="@+id/textView2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="DD No.: "
android:textColor="#FFFFFF"
android:textSize="18sp" />
<TextView
android:id="@+id/dd_no_textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="TextView"
android:textColor="#FFFFFF"
android:textSize="18sp" />
</TableRow>
<TableRow
android:id="@+id/tableRow3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="10dp">
<TextView
android:id="@+id/textView3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Drawn On: "
android:textColor="#FFFFFF"
android:textSize="18sp" />
<TextView
android:id="@+id/drawn_on_textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="TextView"
android:textColor="#FFFFFF"
android:textSize="18sp" />
</TableRow>
<TableRow
android:id="@+id/tableRow4"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="10dp">
<TextView
android:id="@+id/textView4"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Amount: "
android:textColor="#FFFFFF"
android:textSize="18sp" />
<TextView
android:id="@+id/amount_textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="TextView"
android:textColor="#FFFFFF"
android:textSize="18sp" />
</TableRow>
<TableRow
android:id="@+id/tableRow5"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="10dp">
<TextView
android:id="@+id/textView5"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Type: "
android:textColor="#FFFFFF"
android:textSize="18sp" />
<TextView
android:id="@+id/type_textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="TextView"
android:textColor="#FFFFFF"
android:textSize="18sp" />
</TableRow>
<TableRow
android:id="@+id/tableRow6"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="10dp">
<TextView
android:id="@+id/textView6"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Date Time: "
android:textColor="#FFFFFF"
android:textSize="18sp" />
<TextView
android:id="@+id/date_time_textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="TextView"
android:textColor="#FFFFFF"
android:textSize="18sp" />
</TableRow>
</TableLayout>
<EditText
android:id="@+id/remarks_editText"
android:layout_width="500dp"
android:layout_height="wrap_content"
android:layout_below="@+id/table"
android:layout_centerHorizontal="true"
android:layout_marginTop="10dp"
android:background="@drawable/gradientbg"
android:ems="10"
android:hint="Remarks"
android:lines="3"
android:padding="8dp"
android:singleLine="false"
android:textColor="#000000"
android:textCursorDrawable="@null" >
</EditText>
<EditText
android:id="@+id/receipient_name_editText"
android:layout_width="500dp"
android:layout_height="50dp"
android:layout_below="@+id/remarks_editText"
android:layout_centerHorizontal="true"
android:layout_marginTop="10dp"
android:background="@drawable/gradientbg"
android:ems="10"
android:hint="Recepient Name"
android:padding="8dp"
android:singleLine="true"
android:textColor="#000000"
android:textCursorDrawable="@null" >
</EditText>
<RadioGroup
android:id="@+id/acceptance_radioGroup"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/receipient_name_editText"
android:layout_centerHorizontal="true"
android:layout_marginTop="10dp"
android:orientation="horizontal" >
<RadioButton
android:id="@+id/radio0"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:checked="true"
android:text="Accept"
android:textColor="#FFFFFF"
android:textSize="18sp" />
<RadioButton
android:id="@+id/radio1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Reject"
android:textColor="#FFFFFF"
android:textSize="18sp" />
</RadioGroup>
</RelativeLayout>
</ScrollView>
</RelativeLayout>
<RelativeLayout
android:id="@+id/relativeLayout1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="@+id/scrollView1"
android:layout_centerHorizontal="true"
android:layout_marginBottom="5dp" >
<android.gesture.GestureOverlayView
android:id="@+id/customer_sign_gestures"
android:layout_width="fill_parent"
android:layout_height="350dp"
android:background="#FFFFFF"
android:fadeEnabled="false"
android:fadeOffset="5000000000"
android:gestureColor="#000000"
android:gestureStrokeType="multiple"
android:gestureStrokeWidth="3"
android:uncertainGestureColor="#000000" />
<TableRow
android:id="@+id/tableRow7"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/customer_sign_gestures"
android:layout_centerHorizontal="true"
android:layout_marginTop="10dp" >
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:gravity="center_vertical|center_horizontal"
android:orientation="horizontal" >
<Button
android:id="@+id/save_button"
android:layout_width="120dp"
android:layout_height="wrap_content"
android:layout_marginRight="5sp"
android:background="@drawable/btn_blue"
android:text="Save"
android:textColor="#FFFFFF" />
<Button
android:id="@+id/clear_button"
android:layout_width="120dp"
android:layout_height="wrap_content"
android:layout_marginLeft="5sp"
android:background="@drawable/btn_blue"
android:text="Clear"
android:textColor="#FFFFFF" />
</LinearLayout>
</TableRow>
</RelativeLayout>
</LinearLayout>
</RelativeLayout>
这是活动：
public class SupplierCustomerDetailsSignatureActivity extends Activity {
TextView customer_name_textview;
TextView dd_details_textview;
TextView dd_no_textview;
TextView drawn_on_textview;
TextView amount_textview;
TextView type_textview;
TextView date_time_textview;
GestureOverlayView customer_sign_gesture;
Button cancel_btn;
Button save_btn;
String customersSelected;
RelativeLayout headerLayout;
TableRow tableRow1;
TableRow tableRow2;
TableRow tableRow3;
TableRow tableRow4;
TableRow tableRow5;
EditText remarks_edittext;
EditText receipient_name_edittext;
RadioGroup accept_reject_radio;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_supplier_customer_details_signature);
// To remove focus from edittext
this.getWindow().setSoftInputMode(
WindowManager.LayoutParams.SOFT_INPUT_STATE_ALWAYS_HIDDEN);
customer_name_textview = (TextView) findViewById(R.id.customer_name_textView);
dd_details_textview = (TextView) findViewById(R.id.dd_details_textView);
dd_no_textview = (TextView) findViewById(R.id.dd_no_textView);
drawn_on_textview = (TextView) findViewById(R.id.drawn_on_textView);
amount_textview = (TextView) findViewById(R.id.amount_textView);
type_textview = (TextView) findViewById(R.id.type_textView);
date_time_textview = (TextView) findViewById(R.id.date_time_textView);
customer_sign_gesture = (GestureOverlayView) findViewById(R.id.customer_sign_gestures);
headerLayout = (RelativeLayout) findViewById(R.id.layout_1);
tableRow1 = (TableRow) findViewById(R.id.tableRow1);
tableRow2 = (TableRow) findViewById(R.id.tableRow2);
tableRow3 = (TableRow) findViewById(R.id.tableRow3);
tableRow4 = (TableRow) findViewById(R.id.tableRow4);
tableRow5 = (TableRow) findViewById(R.id.tableRow5);
remarks_edittext = (EditText) findViewById(R.id.remarks_editText);
receipient_name_edittext = (EditText) findViewById(R.id.receipient_name_editText);
accept_reject_radio = (RadioGroup) findViewById(R.id.acceptance_radioGroup);
customersSelected = getFromPreference("customer_code_clicked");
if (customersSelected.contains("#@~@#")) {
headerLayout.setVisibility(View.GONE);
tableRow1.setVisibility(View.GONE);
tableRow2.setVisibility(View.GONE);
tableRow3.setVisibility(View.GONE);
tableRow4.setVisibility(View.GONE);
tableRow5.setVisibility(View.GONE);
}
customer_name_textview
.setText(getFromPreference("customer_name_clicked"));
dd_details_textview.setText("Lore Ipsum");
dd_no_textview.setText("7894561230");
drawn_on_textview.setText("State Bank of India");
amount_textview.setText("Rs. 10,000");
type_textview.setText("Cheque");
// makeAToast(customersSelected);
// setting current date
Calendar c = Calendar.getInstance();
SimpleDateFormat df3 = new SimpleDateFormat("dd/MM/yyyy HH:mm:ss a");
String formattedDate = df3.format(c.getTime());
date_time_textview.setText(formattedDate);
cancel_btn = (Button) findViewById(R.id.clear_button);
cancel_btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
clearData();
}
});
save_btn = (Button) findViewById(R.id.save_button);
save_btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
saveData();
}
});
}
@Override
public void onBackPressed() {
// do something on back.
Intent intent = new Intent(
SupplierCustomerDetailsSignatureActivity.this,
SupplierDetailsActivity.class);
finish();
SupplierCustomerDetailsSignatureActivity.this.startActivity(intent);
return;
}
// method to clear data
public void clearData() {
customer_sign_gesture.cancelClearAnimation();
customer_sign_gesture.clear(true);
}
// method to save and send data
public void saveData() {
createIfNotExistDraftToSend();
//checking which radio button is checked
int index = accept_reject_radio.indexOfChild(findViewById(accept_reject_radio.getCheckedRadioButtonId()));
String acceptReject;
if (index ==0)
{
acceptReject ="accept";
}
else
{
acceptReject ="reject";
}
// checking whether edittext contains values
if (remarks_edittext.getText().toString().trim().length() > 0
&& receipient_name_edittext.getText().toString().trim()
.length() > 0) {
// checking whether there is multiple id
if (customersSelected.contains("#@~@#")) {
Log.i("Full String ", customersSelected);
String assetClasses = customersSelected;
String[] splits = assetClasses.split("#@~@#");
for (int k = 1; k < splits.length; k++) {
Log.i("Values", splits[k]);
// getting image
Bitmap gestureImg = customer_sign_gesture.getGesture().toBitmap(100, 100,
8, Color.BLACK);
String image = saveImageToInternalSorage(gestureImg,splits[k], remarks_edittext.getText().toString(),
receipient_name_edittext.getText().toString(), acceptReject, date_time_textview.getText().toString());
Log.i("Image:", image);
}
} else {
}
} else {
makeAToast("Please enter credentials!");
}
}
// Internal storage
private String saveImageToInternalSorage(Bitmap bitmapImage, String cl_doc_no, String remarks,
String recepient, String ar, String mobdttm) {
ContextWrapper cw = new ContextWrapper(getApplicationContext());
// path to /data/data/yourapp/app_data/imageDir
File directory = cw.getDir("imageDir", Context.MODE_PRIVATE);
Random gen = new Random();
int n = 10000;
n = gen.nextInt(n);
String fotoname = "Photo-" + n + ".png";
Log.i("Photo Name:", fotoname);
// Create imageDir
File mypath = new File(directory, fotoname);
FileOutputStream fos = null;
try {
fos = new FileOutputStream(mypath);
// Use the compress method on the BitMap object to write image to
// the OutputStream
bitmapImage.compress(Bitmap.CompressFormat.PNG, 100, fos);
fos.close();
} catch (Exception e) {
e.printStackTrace();
}
//inserting in local database
insertDraftToSend(cl_doc_no, remarks,
recepient, fotoname, ar, mobdttm);
//saveInPreference("Photo",fotoname);
return directory.getAbsolutePath();
}
// ===============Local Database Handling Methods===================
// method to create If Not Exist
public void createIfNotExistDraftToSend() {
DatabaseHandler db = new DatabaseHandler(
SupplierCustomerDetailsSignatureActivity.this);
ContentValues values = new ContentValues();
db.createIfNotExistDraftToSend();
db.close();
}
// method to insert data
public void insertDraftToSend(String cl_doc_no, String remarks,
String recepient, String signature, String ar, String mobdttm) {
DatabaseHandler db = new DatabaseHandler(
SupplierCustomerDetailsSignatureActivity.this);
ContentValues values = new ContentValues();
// db.createDataBase();
values.put("cl_doc_no", cl_doc_no);
values.put("remarks", remarks);
values.put("recepient", recepient);
values.put("signature", signature);
values.put("ar", ar);
values.put("mobdttm", mobdttm);
db.insertDraftToSend(cl_doc_no, remarks, recepient, signature, ar,
mobdttm);
db.close();
}
// ===============Local Database Handling Methods===================
// method to save variable in preference
public void saveInPreference(String name, String content) {
SharedPreferences preferences = PreferenceManager
.getDefaultSharedPreferences(this);
SharedPreferences.Editor editor = preferences.edit();
editor.putString(name, content);
editor.commit();
}
// getting content from preferences
public String getFromPreference(String variable_name) {
String preference_return;
SharedPreferences preferences = PreferenceManager
.getDefaultSharedPreferences(this);
preference_return = preferences.getString(variable_name, "");
return preference_return;
}
// method to show toast message
public void makeAToast(String str) {
// yet to implement
Toast toast = Toast.makeText(this, str, Toast.LENGTH_SHORT);
toast.setGravity(Gravity.CENTER, 0, 0);
toast.show();
}
}
我面临的问题是，如果用户提供签名，那么所需的数据将被插入到本地数据库中，一切都很好，但是如果用户将签名区域保持为空白，那么应用程序将由于以下原因而强制关闭空指针异常。请建议我在插入数据之前如何知道签名区域或 GestureOverlayView 是否为空白。