Android: RadioGroup - How to configure the event listener

问题

From my understanding, to determine if a checkbox is \"clicked\" and find if it\'s checked or not, code such as the following can be used:

cb=(CheckBox)findViewById(R.id.chkBox1);
        cb.setOnCheckedChangeListener(this);

public void onCheckedChanged(CompoundButton buttonView, 
    boolean isChecked) { 
        if (isChecked) { 
            cb.setText(\"This checkbox is: checked\"); 
        } 
        else { 
            cb.setText(\"This checkbox is: unchecked\"); 
        } 
    }

However, I am unable to work out the logic on how to do the above for a radiogroup.

Here is the xml for my RadioGroup:

<RadioGroup android:id=\"@+id/radioGroup1\" 
android:layout_width=\"wrap_content\" 
android:layout_height=\"wrap_content\">
    <RadioButton android:layout_width=\"wrap_content\" 
    android:layout_height=\"wrap_content\" 
    android:id=\"@+id/radio1\" android:checked=\"true\" 
    android:text=\"RadioButton1\">
    </RadioButton>
    <RadioButton android:layout_width=\"wrap_content\" 
    android:layout_height=\"wrap_content\" 
    android:id=\"@+id/radio2\" android:text=\"RadioButton2\" android:checked=\"true\">
    </RadioButton>
    <RadioButton android:layout_width=\"wrap_content\" 
    android:layout_height=\"wrap_content\" 
    android:id=\"@+id/radio3\" android:text=\"RadioButton3\">
    </RadioButton>
</RadioGroup>

Question: Do i need to setup another listener, or will the listener already there also \"register\" this group?

Also, should the listener be set up on the RadioGroup or the RadioButton?

回答1:

This is how you get the checked radiobutton:

// This will get the radiogroup
RadioGroup rGroup = (RadioGroup)findViewById(r.id.radioGroup1);
// This will get the radiobutton in the radiogroup that is checked
RadioButton checkedRadioButton = (RadioButton)rGroup.findViewById(rGroup.getCheckedRadioButtonId());

To use the listener, you do this:

// This overrides the radiogroup onCheckListener
rGroup.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener()
{
    public void onCheckedChanged(RadioGroup group, int checkedId)
    {
        // This will get the radiobutton that has changed in its check state
        RadioButton checkedRadioButton = (RadioButton)group.findViewById(checkedId);
        // This puts the value (true/false) into the variable
        boolean isChecked = checkedRadioButton.isChecked();
        // If the radiobutton that has changed in check state is now checked...
        if (isChecked)
        {
            // Changes the textview's text to "Checked: example radiobutton text"
            tv.setText("Checked:" + checkedRadioButton.getText());
        }
    }
});

回答2:

It should be something like this.

RadioGroup rb = (RadioGroup) findViewById(R.id.radioGroup1);
rb.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
        public void onCheckedChanged(RadioGroup group, int checkedId) {
            switch (checkedId) {

            }
        }

    });

Based on the checkedId, you would know which of the radiobutton has been clicked and then use your above code to figure out if its checked or unchecked. This is homework. ;)

回答3:

Using Switch is better:

radGrp.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
      public void onCheckedChanged(RadioGroup arg0, int id) {
        switch (id) {
        case -1:
          Log.v(TAG, "Choices cleared!");
          break;
        case R.id.chRBtn:
          Log.v(TAG, "Chose Chicken");
          break;
        case R.id.fishRBtn:
          Log.v(TAG, "Chose Fish");
          break;
        case R.id.stkRBtn:
          Log.v(TAG, "Chose Steak");
          break;
        default:
          Log.v(TAG, "Huh?");
          break;
        }
      }
    });

回答4:

//Within the Activity that hosts this layout, the following method handles the click event for both radio buttons:

public void onRadioButtonClicked(View view) {
// Is the button now checked?
boolean checked = ((RadioButton) view).isChecked();

// Check which radio button was clicked
switch(view.getId()) {
    case R.id.radio_pirates:
        if (checked)
            // Pirates are the best
        break;
    case R.id.radio_ninjas:                       
        if (checked)
            // Ninjas rule
        break;
}
}

回答5:

If you want to see which radio Button is checked or selected in the radio group then use the following:

//1. declare the radio group and the radio Button in the java file.
RadioGroup radiobtn;
RadioButton radio;
Button btnClick;
 //the radio is the element of the radiogroup which will assigned when we select the radio button
 //Button to trigger the toast to show which radio button is selected of the radio group


//2. now define them in the java file
radiobtn = findViewById(R.id.radiobtn);
btnClick = findViewById(R.id.btnClick);
 //we are instructing it to find the elements in the XML file using the id


//3. Now Create an on Click listener for the button
btnClick.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            int selectedId = radiobtn.getCheckedRadioButtonId();
             //we are defining the selectId and then we are fetching the id of the checked radio button using the function getCheckedRadioButton()
            radio = findViewById(selectedId);
             //now the radioButton object we have defined will come into play, we will assign the radio to the radio button of the fetched id of the radio group
            Toast.makeText(MainActivity.this,radio.getText(),Toast.LENGTH_SHORT).show();
             //we are using toast to display the selected id of the radio button
             //radio.getText() will fetch the id of the radio Button of the radio group
        }
    });

来源：https://stackoverflow.com/questions/6780981/android-radiogroup-how-to-configure-the-event-listener