RadioGroup: How to check programmatically

问题

I create a RadioGroup from XML

    <RadioGroup android:id="@+id/option" 
        android:layout_width="match_parent"
        android:orientation="horizontal" 
        android:checkedButton="@+id/block_scenario_off"
        android:layout_height="wrap_content">
        <RadioButton 
            android:layout_width="0dip"
            android:layout_weight="1" 
            android:text="@string/option1" 
            android:layout_height="wrap_content" 
            android:id="@+id/option1"
            android:layout_gravity="center|left" 
            android:onClick="@string/on_click"/>
        <RadioButton 
            android:layout_width="0dip"
            android:layout_weight="1" 
            android:text="@string/option2" 
            android:onClick="@string/on_click"
            android:layout_height="wrap_content"
            android:layout_gravity="center" 
            android:id="@+id/option2"/>
        <RadioButton 
            android:layout_width="0dip"
            android:layout_weight="1" 
            android:text="@string/option3"
            android:onClick="@string/on_click" 
            android:layout_height="wrap_content"
            android:layout_gravity="center|right" 
            android:id="@+id/option3" />
    </RadioGroup>

In Java code, I programmatically check the first one on activity creation (onCreate()) as following:

    mOption = (RadioGroup) findViewById(R.id.option);
    mOption.check(R.id.option1);

But when the activity is shown, no radio button is checked. Any help?

回答1:

In your layout you can add android:checked="true" to CheckBox you want to be selected.

Or programmatically, you can use the setChecked method defined in the checkable interface:

RadioButton b = (RadioButton) findViewById(R.id.option1); b.setChecked(true);

回答2:

try this if you want your radio button to be checked based on value of some variable e.g. "genderStr" then you can use following code snippet

    if(genderStr.equals("Male"))
       genderRG.check(R.id.maleRB);
    else 
       genderRG.check(R.id.femaleRB);

回答3:

You may need to declare the radio buttons in the onCreate method of your code and use them.

RadioButton rb1 = (RadioButton) findViewById(R.id.option1);
rb1.setChecked(true);

回答4:

Watch out! checking the radiobutton with setChecked() is not changing the state inside the RadioGroup. For example this method from the radioGroup will return a wrong result: getCheckedRadioButtonId().

Check the radioGroup always with

mOption.check(R.id.option1);

you've been warned ;)

回答5:

Grab the radio group and look at the children to see if any are unchecked.

RadioGroup rg = (RadioGroup) view;
int checked = savedInstanceState.getInt(wrap.getAttributeName());

if(checked != -1) {
    RadioButton btn = (RadioButton) rg.getChildAt(checked);
    btn.toggle();
}

回答6:

Also you can use getChildAt() method. Like this:

mOption = (RadioGroup) findViewById(R.id.option);
((RadioButton)mOption.getChildAt(0)).setChecked(true);

回答7:

I use this code piece while working with indexes for radio group:

radioGroup.check(radioGroup.getChildAt(index).getId());

回答8:

it will work if you put your mOption.check(R.id.option1); into onAttachedToWindow method or like this:

view.post(new Runnable()
{
    public void run() 
    {
        // TODO Auto-generated method stub
        mOption.check(R.id.option1); 
    }
});

the reason may be that check method will only work when the radiogroup is actually rendered.

回答9:

I use this code piece while working with getId() for radio group:

radiogroup.check(radiogroup.getChildAt(0).getId());

set position as per your design of RadioGroup

hope this will help you!

来源：https://stackoverflow.com/questions/7743212/radiogroup-how-to-check-programmatically

标签

android

radio-group