Android：如何在Java中以编程方式检查/取消选中RadioGroup中的RadioButton

Question

I have to activities, MainActivity and settingsActivity. Because of that I'm using the methods onPause and onResume in the settingsActivity. So that the things I have done in the settingsActivity are saved after switching to MainActivity and back again.

settingsActivity:

Here I have a TextView (called "settings2") as a kind of variable and my three RadioButtons ( radio0 , radio1 and radio2 ) which are inside a RadioGroup . After switching to the MainActivity my programe puts "0" in a file (which is saved on the sdcard) if radio0 was last checked. But if radio1 was last checked, it puts 1 in that file. And if radio2 was last checked, it puts 2 in that file. I used this in the method onPause .

Then in the method onResume I read the text of that file and put it in the TextView "settings2". After this code (still in onResume ) I want to check/uncheck my RadioButtons . So if the text of the TextView "settings2" is "0" the RadioButton "radio0" shall be checked and the others not. If the text of this TextView is "1" the RadioButton "radio1" shall be checked and the others not. And if the text of this TextView is "2" the RadioButton "radio2" shall be checked and the others not. To do this I used the following two codes but unfortunately they didn't work.

First code:

if (settings2.getText().equals("0")) {

        radio0.setChecked(true);
        radio1.setChecked(false);
        radio2.setChecked(false);

    } else if (settings2.getText().equals("1")) {

        radio0.setChecked(false);
        radio1.setChecked(true);
        radio2.setChecked(false);

    } else if (settings2.getText().equals("2")) {

        radio0.setChecked(false);
        radio1.setChecked(false);
        radio2.setChecked(true);

    } 

Second code:

if (settings2.getText().equals("0")) {

        radioGroup1.check(R.id.radio0);

    } else if (settings2.getText().equals("1")) {

        radioGroup1.check(R.id.radio1);

    } else if (settings2.getText().equals("2")) {

        radioGroup1.check(R.id.radio2);

    } 

Can someone help with this little problem please? I'm looking forward to your help!

Thanks in advance!

Answer 1

Here's the problem.

 EditText et = ....
 et.getText() // Does not return a string, it returns an Editable.

Try:

String str = et.getText().toString;

Then using str to do your comparisons.

Edit: See source code below on why u have to use Strings to compare. The default is to compare by reference, but Strings have overriden equals to compare based on string values. If you aren't using String u won't get matches.

public boolean More ...equals(Object anObject) {
    if (this == anObject) {
        return true;
    }
    if (anObject instanceof String) {
        String anotherString = (String)anObject;
        int n = count;
        if (n == anotherString.count) {
            char v1[] = value;
            char v2[] = anotherString.value;
            int i = offset;
            int j = anotherString.offset;
            while (n-- != 0) {
                if (v1[i++] != v2[j++])
                    return false;
            }
            return true;
        }
    }
    return false;
}

Answer 2

Are you sure the TextView text is either 0, 1, or 2? And for a setting like this, you should look into SharedPreferences ! It is much easier to use and much faster too.

2nd thing you should do is instead of getting the settings2.getText().toString () you should do

int input = Integer.parseInt (settings2.getText().toString()

and then use

switch(input) {
    case 0:
        // code when text equals 0
    break;
    case 1:
        // code when text equals 1
    break;
    case 2:
        // code when text equals 2
    break;
}

Look into this. . I'm on mobile at the moment

EDIT: Formatted text for better view.

EDIT 2 : SharedPreferences example

//get your app's Preference Manager
SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context); // If you are coding this in your Activity class, you have to use getDefaultSharedPreferences(this) instead!

public int getPrefs(String key) {
    //get an Integer from the preferences
    return prefs.getInt(key, defaultValue);
    //defaultValue is in case a value for the given key is not found, for example, the user runs the app for the 1st time.
}

public void setPrefs() {
    //You need a SharedPreference editor
    SharedPreferences.Editor prefsEditor = prefs.edit();
    //SharedPreference work with a key and its value
    prefsEditor.putInt(key, value);
    //You have to commit the preferences, or they don't get saved!
    //If you want to use a save button, you can make the Editor variable into a Global var (class variable) and in your save button's onClick, just commit!
    prefsEditor.commit();
}