如何检查哪个单选按钮被选中了？[ANDROID]

Question

我正在使用两个包含多个单选按钮的单选组，想要检查哪个单选按钮被选中，以便可以相应地调用特定的函数。我正在使用getCheckedRadioButtonId方法来实现，但是它抛出了空指针异常。如何正确地解决这个问题？我已经尝试过其他方法。 任何帮助都将不胜感激。 以下是我的代码

public class MainActivity extends AppCompatActivity {
private EditText et_name;
private EditText et_age;
private EditText et_contactno;

private RadioGroup radioGroup_gender;
private RadioButton radioButton_male;
private RadioButton radioButton_female;
private RadioGroup radioGroup_methods;
private RadioGroup radioGroup_intent_methods;
private RadioButton radioButton_textfile;
private RadioButton radioButton_sharefpref;
private RadioButton radioButton_database;
private RadioButton radioButton_staticfields;
private RadioButton radioButton_intents;
private RadioButton radioButton_direct;
private RadioButton radioButton_bundle;
private RadioButton radioButton_parcelable;

private String name;
private String age;
private String contact_no;
private String gender;

private int gender_selected_id;
private int transfer_method_selected_id;
private int selected_intent_method_id;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);
    findViewsByIds();
    FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
    fab.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Snackbar.make(view, "FAB CLICKED", Snackbar.LENGTH_LONG)
                    .setAction("Action", null).show();
            executeSelectedMethod();
        }
    });
}

private void findViewsByIds() {
    et_name = (EditText) findViewById(R.id.et_name);
    et_age = (EditText) findViewById(R.id.et_age);
    et_contactno = (EditText) findViewById(R.id.et_contactno);
    radioGroup_gender = (RadioGroup) findViewById(R.id.rg_gender);
    radioButton_male = (RadioButton) findViewById(R.id.rb_male);
    radioButton_female = (RadioButton) findViewById(R.id.rb_female);

    radioGroup_methods = (RadioGroup) findViewById(R.id.rg_methods);
    radioGroup_intent_methods = (RadioGroup) findViewById(R.id.rg_intentmethods);
    radioButton_textfile = (RadioButton) findViewById(R.id.rb_textfile);
    radioButton_sharefpref = (RadioButton) findViewById(R.id.rb_sharefpref);
    radioButton_database = (RadioButton) findViewById(R.id.rb_database);
    radioButton_staticfields = (RadioButton) findViewById(R.id.rb_static);
    radioButton_intents = (RadioButton) findViewById(R.id.rb_intent);
    radioButton_direct = (RadioButton) findViewById(R.id.rb_intent_direct);
    radioButton_bundle = (RadioButton) findViewById(R.id.rb_intent_bundle);
    radioButton_parcelable = (RadioButton) findViewById(R.id.rb_intent_parcelable);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.menu_main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        return true;
    }

    return super.onOptionsItemSelected(item);
}

private void executeSelectedMethod() {
    try {
        name = et_name.getText().toString();
        age = et_age.getText().toString();
        contact_no = et_contactno.getText().toString();
        RadioButton rb = (RadioButton) findViewById(radioGroup_gender.getCheckedRadioButtonId());
        String selectedgender = rb.getText().toString();
        if (selectedgender.equalsIgnoreCase("Male")) {
            gender = radioButton_male.getText().toString();
        } else if (selectedgender.equalsIgnoreCase("Female")) {
            gender = radioButton_female.getText().toString();
        }
        RadioButton rb_selected_method = (RadioButton) findViewById(radioGroup_gender.getCheckedRadioButtonId());
        String selectedRadioButtontext = rb_selected_method.getText().toString();
        if (selectedRadioButtontext.equalsIgnoreCase("Text File")) {
            ConstantFile.TRANSFER_METHOD = radioButton_textfile.getText().toString();
            executeTextFileMethod();
        } else if (transfer_method_selected_id == R.id.rb_sharefpref) {
            ConstantFile.TRANSFER_METHOD = radioButton_sharefpref.getText().toString();
        } else if (transfer_method_selected_id == R.id.rb_database) {
            ConstantFile.TRANSFER_METHOD = radioButton_database.getText().toString();
        } else if (transfer_method_selected_id == R.id.rb_static) {
            ConstantFile.TRANSFER_METHOD = radioButton_staticfields.getText().toString();
        } else {

            selected_intent_method_id = radioGroup_intent_methods.getCheckedRadioButtonId();
            if (selected_intent_method_id == R.id.rb_intent_direct) {
                ConstantFile.TRANSFER_METHOD = radioButton_direct.getText().toString();
            } else if (selected_intent_method_id == R.id.rb_intent_bundle) {
                ConstantFile.TRANSFER_METHOD = radioButton_bundle.getText().toString();

            } else if (selected_intent_method_id == R.id.rb_intent_parcelable) {
                ConstantFile.TRANSFER_METHOD = radioButton_parcelable.getText().toString();

            }
        }
    } catch (IOException e) {
        e.printStackTrace();
    }
}

private void executeTextFileMethod() throws IOException {
    File transfer_file = new File("/sdcard/" + name + ".txt");
    transfer_file.createNewFile();
    FileOutputStream fileoutputstrem = new FileOutputStream(transfer_file);
    OutputStreamWriter outstreamwriter = new OutputStreamWriter(fileoutputstrem);
    outstreamwriter.append(name + ":" + age + ":" + contact_no + ":" + gender);
    fileoutputstrem.close();
    outstreamwriter.close();
    Toast.makeText(this, "This is my Toast message!",
            Toast.LENGTH_LONG).show();
    ConstantFile.TXTFILENAME = transfer_file.getName();
    goToNextActivity();
}

private void goToNextActivity() {
    Intent intent = new Intent(MainActivity.this, Main2Activity.class);
    startActivity(intent);
}}

这是异常:

Process: com.phaseone_datatransferbetweenactivities, PID: 22385
java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.CharSequence android.widget.RadioButton.getText()' on a null object reference
at com.phaseone_datatransferbetweenactivities.MainActivity.executeSelectedMethod(MainActivity.java:118)
at com.phaseone_datatransferbetweenactivities.MainActivity.access$000(MainActivity.java:23)
at com.phaseone_datatransferbetweenactivities.MainActivity$1.onClick(MainActivity.java:65)
at android.view.View.performClick(View.java:5265)
at android.view.View$PerformClick.run(View.java:21534)
at android.os.Handler.handleCallback(Handler.java:815)
at android.os.Handler.dispatchMessage(Handler.java:104)
at android.os.Looper.loop(Looper.java:207)
at android.app.ActivityThread.main(ActivityThread.java:5728)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:789)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:679)

- User

---

你可以在单选按钮组上设置setOnCheckedChangeListener()，然后你就可以获取被选中的单选按钮的id。 - Ganesh Gudghe

我认为你应该在单选按钮组中设置一个默认选中状态的单选按钮。例如，在性别按钮中，男性或女性应该被选中。然后当你调用radioGroup_gender.getCheckedRadioButtonId()时，它将始终返回id。如果没有选中任何一个，就会返回null。 - federico verchez

Answer 1

这个运行得非常完美：

RadioGroup radioGroup = (RadioGroup) findViewById(R.id.radio_group);

int radioButtonID = radioGroup.getCheckedRadioButtonId();

RadioButton radioButton = (RadioButton) radioGroup.findViewById(radioButtonID);

String selectedText = (String) radioButton.getText();

- vijay chhalotre

Answer 2

尝试使用这个，它对我也有效。

radioGroup.setOnCheckedChangeListener(new OnCheckedChangeListener() {

            @Override
            public void onCheckedChanged(RadioGroup rGroup, int checkedId) {

                int radioBtnID = rGroup.getCheckedRadioButtonId();

                View radioB = rGroup.findViewById(radioBtnID);

                int position = group.indexOfChild(radioB);
            }
        });

- vijay chhalotre

Answer 3

尝试这个方法，对于同时获取id和文本信息很有效。

radioGroup = findViewById(R.id.radio_group);
    radioGroup.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {

        @Override
        public void onCheckedChanged(RadioGroup rGroup, int checkedId) {
            int radioButtonID = radioGroup.getCheckedRadioButtonId();
            View radioButton = radioGroup.findViewById(radioButtonID);
            int idx = radioGroup.indexOfChild(radioButton);
            RadioButton r = (RadioButton) radioGroup.getChildAt(idx);
            String selectedText = r.getText().toString();
            System.out.println(idx);//For print Id
            System.out.println(selectedText);//For print Text
        }
    });

- Aftab Alam

Answer 4

使用以下代码。

RadioGroup rg = your_radio_group;

// It will return currently selected radio button id from RadioGroup
int id = rg.getCheckedRadioButtonId();

if(id == your_one_radio_button_id){
 // First radio button is selected.
} else if(id == your_two_radio_button_id){
 // Second radio button is selected.
}

- Jitesh Dalsaniya

---

我已经使用过它，但它没有返回那个单选按钮的ID，而是返回类似于“345323”的值。 - User

你已经检查了if条件的结果吗？如果有多个单选按钮，你需要使用if else if。请检查更新后的答案。 - Jitesh Dalsaniya

@user：我认为你得到的是类似于 R.id.yourid 的东西的内部表示。 - federico verchez

Answer 5

 int radioButtonID = radioButtonGroup.getCheckedRadioButtonId();

 View radioButton = radioButtonGroup.findViewById(radioButtonID);

 int idx = radioButtonGroup.indexOfChild(radioButton);

如果RadioGroup包含其他视图（如TextView等），则indexOfChild()方法将返回错误的索引。 在RadioGroup中获取选定的RadioButton文本

 RadioButton r = (RadioButton)  radioButton .getChildAt(idx);

 String selectedtext = r.getText().toString();

- vijay chhalotre

Answer 6

这对我有用 - 在Java中，选择活动片段内的单选按钮组中的选中单选按钮。

RadioGroup radioGroup = getActivity().findViewById(R.id.radioGroup);
int checked = radioGroup.getCheckedRadioButtonId();

- nitrotap

Answer 7

我这样使用是因为一些RadioButton是以编程方式添加的，findViewById()返回了null。

fun getContactPhoneNumber(): String {
    val checkedView = viewBinding.phoneNumbersRadioGroup.children.firstOrNull {
        it.id == viewBinding.phoneNumbersRadioGroup.checkedRadioButtonId
    }
    if (checkedView?.id == OTHER.hashCode()) {
        return viewBinding.otherPhoneNumberTextView.text.toString()
    }
    return checkedView?.tag as? String ?: ""
}

- Dan Alboteanu

Answer 8

                int id = radioGroup.getCheckedRadioButtonId(); 
                 if(id!=-1){
                    int radioButtonID = radioGroup.getCheckedRadioButtonId();
                    RadioButton radioButton = 
                        (RadioButton)radioGroup.findViewById(radioButtonID);

                    String selectedtext = (String) radioButton.getText();
                      Toast.makeText(ReportsAct.this, ""+selectedtext, 
                       Toast.LENGTH_SHORT).show();
                }

- Syed Danish Haider

Answer 9

radioGroup = view.findViewById(R.id.choices);
 try {
       radioGroup.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() 
       {
            @Override
            public void onCheckedChanged(RadioGroup group, int checkedId) {
                RadioButton radioButton = view.findViewById(checkedId);
                //selected index
                mctSelectedAnsIndex = checkedId;
                Log.e("mctSelectedAnsIndex",mctSelectedAnsIndex+"-"+checkedId);
                int j = radioGroup.getChildCount();
               //changing background of all radio buttons in group
                for (int i = 0; i < j; i++) {
 radioGroup.getChildAt(i).setBackgroundColor(getActivity().getApplicationContext().
 getResources().getColor(R.color.lgrey));
                }

//code for changing background of selected one                      

radioButton.setBackgroundColor(getActivity().getApplicationContext().
getResources().getColor(R.color.color2));

                if (mctSelectedAnsIndex == correctAnsChoice){
                    rightAnswers++;
                }else{
                    wrongAnswers++;
                }

            }
        });
    } catch (Exception e) {
        e.printStackTrace();
    }

- Sreejesh K Nair