执行back和cancelbutton的区别？

Question

I ma newbie an trying to learn Java/Android-programming.

I m doing an app for Android in Eclipse and created some buttons. I have a back and a cancel button.

Example:

I have a EditText there you can write in your name. If you write yourname and press the backbutton, then u will go back to the previous Activity, but if you go to the same Activity, then you will still see the name that you wrote in the EditText.

But if you press the cancelbutton, you will go back to the previous Activity, but when you come back, yourname will be empty. I will "kill" or "stop" the Activity.

This is the code I use for the Backbutton, what would you use for the Cancel Button? Thank YOU.

public void onClick(View v) {
    switch(v.getId()){
    case R.id.buttonBack:
        Intent intent = new Intent (AllActivity.this, MenuActivity.class);
        startActivity(intent);
        break;

Answer 1

For the cancel button you can use the below method, this will kill the activity.

 finish()

so in your code it will look something like this:

 public void onClick(View v) {
     switch(v.getId()){
     case R.id.cancel:
         finish();
         break;

Answer 2

There was little difference in this as per requirement of process or application flow. For cancel and back as work are same for example if you open any dialog and provide cancel button will close/dismiss your dialog same way the back button do this. While for implementing with the Activity you if you implement for closing current activity you can just finish with both option by just calling finish() method. As back button was normally work for finish you current activity and back.

Answer 3

Another way to do this that you may be interested in is to wipe out the content of the EditText yourself. You would need to have in your xml file an id defined for the EditText so that you could access it programatically.

<EditText

layout stuff here:

    android:layout_width="fill_parent"

... and then the id attribute

    android:id="@+id/edit_text_id"
    >

then in your code you would put the following in your class (not inside any method):

EditText anEditText;

then in your onCreate(), after the inflation of the layout (if it comes beforehand it will cause the app to crash):

anEditText = (EditText) findViewById(R.id.edit_text_id);

the name edit_text_id is not significant, but it is what we used in the layout file

next add to the onClick method for cancel (after the case statement):

//this wipes the text from the textbox
anEditText.setText("");
// add the rest of the back button code after this and your good!

Best of luck! Remember that we were all newbies once. If you want to be a good android programmer, I suggest that you get a strong background in Java first. This free book helped me very much!

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