问题
I am using two radio groups with multiple radio buttons, I want to check which radio button is selected so that I can call specific functions accordingly. I am using getCheckedRadioButtonId method to do this, but it's throwing null pointer exception. How this can be done in a correct way? I have tried other methods too. Any help will be appreciated. Here is my code
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);
}}
This is the exception:
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)
回答1:
Its working perfactly
RadioGroup radioGroup = (RadioGroup) findViewById(R.id.radio_group);
int radioButtonID = radioGroup.getCheckedRadioButtonId();
RadioButton radioButton = (RadioButton)
radioGroup.findViewById(radioButtonID);
String selectedtext = (String) radioButton.getText();
回答2:
Try to use this one its also working for me
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);
}
});
回答3:
Use following code.
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.
}
回答4:
int radioButtonID = radioButtonGroup.getCheckedRadioButtonId();
View radioButton = radioButtonGroup.findViewById(radioButtonID);
int idx = radioButtonGroup.indexOfChild(radioButton);
If the RadioGroup contains other Views (like a TextView etc..) then the indexOfChild() method will return wrong index. to get selected RadioButton Text on RadioGroup
RadioButton r = (RadioButton) radioButton .getChildAt(idx);
String selectedtext = r.getText().toString();
回答5:
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();
}
回答6:
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();
}
回答7:
try this one, working for me for getting id and text both
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
}
});
来源：https://stackoverflow.com/questions/42502055/how-to-check-which-radio-button-of-a-radio-group-is-selected-android