获取选中的单选按钮

Question

我想创建动态 RadioGroup（带有动态单选选项）。我正在使用以下代码。

我的问题是，我怎样才能通过单击“Check Answer”按钮获得选择的选项。如果无线电组是通过 XML 布局添加的，那么我可以通过它的 ID 获取，但在这种情况下我无法这样做。

代码如下：

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">

    <LinearLayout
        android:id="@+id/linear_layout"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:orientation="vertical"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintBottom_toTopOf="@+id/button">
    </LinearLayout>

    <TextView
        android:id="@+id/answer"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:layout_constraintBottom_toTopOf="@+id/button"
        android:textColor="#008b00"
        />

    <Button
        android:id="@+id/button"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Check Answer"
        app:layout_constraintBottom_toBottomOf="parent"
        android:onClick="checkAnswer"
        />
</androidx.constraintlayout.widget.ConstraintLayout>

MainActivity：

package com.example.quiz8;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.View;
import android.widget.LinearLayout;
import android.widget.RadioButton;
import android.widget.RadioGroup;
import android.widget.TextView;

import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {

    private LinearLayout linearLayout = null;

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

        linearLayout = (LinearLayout) findViewById(R.id.linear_layout);
        RadioGroup radioGroup = new RadioGroup(this);
        RadioButton radioButton;

        final String[] title = {"Male", "Female", "Other", "Secret"};

        for (int i = 0; i < title.length; i++) {
            radioButton = new RadioButton(this);
            radioButton.setId(i);
            radioButton.setText(title[i]);
            radioGroup.addView(radioButton);
        }

        linearLayout.addView(radioGroup);
    }

    public void checkAnswer(View view) {
        //get the answer here
        TextView answerText = (TextView) findViewById(R.id.answer);
        answerText.setText("You selected the option...");
    }
}

Answer 1

您可以为RadioGroup 设置一个标签，以便能够轻松找到它。 标签 可以是任何Object。我们将在这里使用String，它在您调用findViewWithTag() 的ViewGroup 中必须是唯一的。然后在checkAnswer() 中，您通过其标签 检索RadioGroup，从而获得选中的RadioButton 的文本。

private static final String RADIOGROUP_TAG = "radiogroup";

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

    linearLayout = (LinearLayout) findViewById(R.id.linear_layout);
    RadioGroup radioGroup = new RadioGroup(this);
    radioGroup.setTag(RADIOGROUP_TAG);

    RadioButton radioButton;

    final String[] title = {"Male", "Female", "Other", "Secret"};

    for (int i = 0; i < title.length; i++) {
        radioButton = new RadioButton(this);
        radioButton.setId(i);
        radioButton.setText(title[i]);
        radioGroup.addView(radioButton);
    }

    linearLayout.addView(radioGroup);
}

public void checkAnswer(View view) {
    //get the answer here
    RadioGroup radioGroup = linearLayout.findViewWithTag(RADIOGROUP_TAG);
    int checkedId = radioGroup.getCheckedRadioButtonId();
    RadioButton radioButton = radioGroup.findViewById(checkedId);
    String text = radioButton.getText().toString();

    TextView answerText = (TextView) findViewById(R.id.answer);
    answerText.setText("You selected the option..." + text);
}

---

另一种选择：您可以将String[] title 和RadioGroup 作为Activity 中的字段。这是有道理的，因为您在不止一个地方需要它们。

private final String[] title  = {"Male", "Female", "Other", "Secret"};
private RadioGroup radioGroup;

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

    linearLayout = (LinearLayout) findViewById(R.id.linear_layout);
    radioGroup = new RadioGroup(this);

    RadioButton radioButton;

    for (int i = 0; i < title.length; i++) {
        radioButton = new RadioButton(this);
        radioButton.setId(i);
        radioButton.setText(title[i]);
        radioGroup.addView(radioButton);
    }

    linearLayout.addView(radioGroup);
}

public void checkAnswer(View view) {
    //get the answer here
    int checkedId = radioGroup.getCheckedRadioButtonId();
    TextView answerText = (TextView) findViewById(R.id.answer);
    // Note: make sure there is a checked RadioButton! 
    answerText.setText("You selected the option..." + title[checkedId]);
}

Answer 2

您可以简单地检查所选的。

public class MainActivity extends AppCompatActivity {

    private LinearLayout linearLayout = null;

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

        linearLayout = (LinearLayout) findViewById(R.id.linear_layout);
        RadioGroup radioGroup = new RadioGroup(this);
        RadioButton radioButton;

        final String[] title = {"Male", "Female", "Other", "Secret"};

        for (int i = 0; i < title.length; i++) {
            radioButton = new RadioButton(this);
            radioButton.setId(i);
            radioButton.setText(title[i]);
            radioGroup.addView(radioButton);
            radioGroup.setOnCheckedChangeListener(new OnCheckedChangeListener() {
                @Override
                public void onCheckedChanged(RadioGroup group, int checkedId) {
                //checkedId is the RadioButton selected
            }

        }

        linearLayout.addView(radioGroup);
    }

    public void checkAnswer(View view) {
        //get the answer here
        TextView answerText = (TextView) findViewById(R.id.answer);
        answerText.setText("You selected the option...");
    }
}

Answer 3

1) 您可以在OnClickListner() 中添加以下代码以检查是否单击了所需的复选框。

// 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;
}

更多帮助可以在单选按钮文档中找到：Radio Button Documentation

2) 另一种方法：更好的方法是使用RadioGroup 并在其上设置监听器以相应地更改和更新视图（节省您拥有 2 个或 3 个或 4 个等监听器）。

RadioGroup radioGroup = (RadioGroup) findViewById(R.id.yourRadioGroup);        
radioGroup.setOnCheckedChangeListener(new OnCheckedChangeListener() 
{
    @Override
    public void onCheckedChanged(RadioGroup group, int checkedId) {
        // checkedId is the RadioButton selected
    }
});