尝试获取电话号码时，为什么我的活动崩溃了？

Question

I have an activity, called AddItem , which contains a couple fields that the user fills out and I am now trying to pass them to another activity. I was able to get the first two fields by doing this:

String messageText = ((EditText) findViewById(R.id.inputName)).getText().toString();
String discriptionText = ((EditText) findViewById(R.id.description)).getText().toString();

The above code worked fun, but then I tried to get another value which I then cast to a double like so:

double Latitude = Double.parseDouble(((EditText) findViewById(R.id.Latitude)).getText().toString());

It's kind of long and complicated but I'm basically doing the same thing with the exception of parsing the String and converting it to a double value. I determined that this is the problem code because when I comment it out the rest of the app runs fine.

Here is my Activity:

public class AddItem extends AppCompatActivity {

  EditText inputedTask, inputedDescription, inputedLatitude;

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_add_item);
    inputedTask = (EditText) findViewById(R.id.inputName);
    inputedDescription = (EditText) findViewById(R.id.description);
    inputedLatitude = (EditText) findViewById(R.id.Latitude);
  }

  public void onSaveItemButton(View view) {
    String messageText = ((EditText) findViewById(R.id.inputName)).getText().toString();
    String discriptionText = ((EditText) findViewById(R.id.description)).getText().toString();
    double Latitude = Double.parseDouble(((EditText) findViewById(R.id.Latitude)).getText().toString());

    if (messageText.equals(""));
    else {
      Intent intent = new Intent();
      intent.putExtra(Intent_Constant.INTENT_MESSAGE_FIELD, messageText);
      setResult(Intent_Constant.INTENT_RESULT_CODE, intent);
      finish();
    }
  }
}

Answer 1

You need to make a public method for the onClick, from the documentation :

Within the Activity that hosts this layout, the following method handles the click event:

 /** Called when the user touches the button */ public void sendMessage(View view) { // Do something in response to button click } 

The method you declare in the android:onClick attribute must have a signature exactly as shown above. Specifically, the method must:

• Be public
• Return void
• Define a View as its only parameter (this will be the View that was clicked)

So you need to change the method to public :

public void onSaveItemButton(View view) {
  ...
}

UPDATE:
As the error log says:

at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698) Caused by: java.lang.NumberFormatException: Invalid double: "" at java.lang.StringToReal.invalidReal(StringToReal.java:63) at java.lang.StringToReal.parseDouble(StringToReal.java:267) at java.lang.Double.parseDouble(Double.java:301) at cs4720.cs.virginia.edu.duysalahandroidminiproject02.AddItem.onSaveItemButton(AddItem.java:33)

You need to catch for empty string in the following code:

double Latitude = Double.parseDouble(((EditText) findViewById(R.id.Latitude)).getText().toString());

so, check it first:

String val = ((EditText) findViewById(R.id.Latitude)).getText().toString();
if(!val.equals("") {
  double Latitude = Double.parseDouble(val);
}

Answer 2

You are calling onSaveItemButton method from a view that is not initialized. You must initialize btnChangeDate in the onCreate from the activity.

Check this answer