Android：RadioGroup - 如何配置事件监听器

Question

根据我的理解，要确定一个复选框是否被“单击”并确定它是否被选中，可以使用如下代码：

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"); 
        } 
    }

但是，我无法计算出如何对单选组执行上述操作的逻辑。

以下是我的 RadioGroup 的 xml：

<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>

问题：我是否需要设置另一个侦听器，或者已经存在的侦听器也会“注册”该组吗？

另外，监听器应该设置在 RadioGroup 还是 RadioButton 上？

Answer 1

这是获取选中单选按钮的方法：

// 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());

要使用侦听器，您可以执行以下操作：

// 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());
        }
    }
});

Answer 2

应该是这样的。

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

            }
        }

    });

根据checkedId，您将知道哪个单选按钮已被单击，然后使用上面的代码来确定其是否已选中或未选中。这是家庭作业。 ;)

Answer 3

使用 Switch 更好：

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;
        }
      }
    });

Answer 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;
}
}

Answer 5

如果您想查看单选按钮组中选中或选择的单选按钮，请使用以下命令：

//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
        }
    });

Answer 6

我的 MainActivity.java

package com.example.endsempracmad;

import android.content.Intent;
import android.os.Bundle;
import android.view.ContextMenu;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.RadioButton;
import android.widget.RadioGroup;
import android.widget.Toast;

import androidx.appcompat.app.ActionBar;
import androidx.appcompat.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity {
String selection;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    ActionBar actionBar = getSupportActionBar();
    actionBar.setTitle("Home Activity");

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




    Button myButton = findViewById(R.id.button);

    myButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            // Create an intent to start the new activity
            Intent intent = new 
 Intent(MainActivity.this,SecondActivity.class);
            int selectedId = radioGroup.getCheckedRadioButtonId();
            if(selectedId != -1){
                RadioButton selectedRadioButton = findViewById(selectedId);
                selection = selectedRadioButton.getText().toString();


            }
            intent.putExtra("selection", selection);
            startActivity(intent);

            // Start the new activity
            startActivity(intent);
        }
    });

    //Toast.makeText(getApplicationContext(),"Hello Javatpoint",Toast.LENGTH_SHORT).show();

}
}

Activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout             
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">

 <Button
    android:id="@+id/button"
    android:layout_width="267dp"
    android:layout_height="123dp"
    android:layout_marginStart="45dp"
    android:layout_marginTop="450dp"
    android:layout_marginEnd="99dp"
    android:layout_marginBottom="158dp"
    android:text="Button"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent" />

 <RadioGroup
    android:id="@+id/my_radio_group"
    android:layout_width="166dp"
    android:layout_height="248dp"
    android:layout_marginStart="34dp"
    android:layout_marginTop="129dp"
    android:layout_marginEnd="211dp"
    android:layout_marginBottom="354dp"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent">

    <RadioButton
        android:layout_width="wrap_content"
        android:layout_height="69dp"
        android:background="@drawable/messi"
        android:text="Radio button 1" />

    <RadioButton
        android:layout_width="120dp"
        android:layout_height="81dp"
        android:background="@drawable/messi"
        android:text="Radio button 2" />

    <RadioButton
        android:layout_width="123dp"
        android:layout_height="84dp"
        android:background="@drawable/messi"

        android:text="Radio button 3" />
</RadioGroup>


</androidx.constraintlayout.widget.ConstraintLayout>

SecondActivity.java

package com.example.endsempracmad;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.widget.TextView;

public class SecondActivity extends AppCompatActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_second);

    String selection = getIntent().getStringExtra("selection");
    TextView textView = findViewById(R.id.textView);
    textView.setText("Selected option: " + selection);

}
}

Activity_Second.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".SecondActivity">

<TextView
    android:id="@+id/textView"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="TextView"
    tools:layout_editor_absoluteX="212dp"
    tools:layout_editor_absoluteY="113dp" />
</androidx.constraintlayout.widget.ConstraintLayout>