Question

我对RadioGroups有点麻烦。我在布局中创建了一个空白的无线电组。然后在代码中用均衡器预设填充它。然后我尝试使用radiogroup.check（1）设置其中一个选项。但它抛出了空指针异常。

以下是代码：

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.equalizer);
    //rgEqualizer = (RadioGroup) findViewById(R.id.rgEqualizerPreset);
    mPlayer = new MediaPlayer();
    mEqualizer = new Equalizer(0, AuID);
    rgEqualizer = new RadioGroup(this);
    radioButtonList = new ArrayList<RadioButton>();
    layoutParams = new RadioGroup.LayoutParams(
        RadioGroup.LayoutParams.FILL_PARENT,
        RadioGroup.LayoutParams.WRAP_CONTENT);

    fillRadioGroupWithRadioButtons();
    rgEqualizer.setEnabled(true);
    rgEqualizer.setOnCheckedChangeListener(this);
    addContentView(rgEqualizer, layoutParams);
    loadPresetsettings();
}
private void fillRadioGroupWithRadioButtons() {
    Short noPresets = mEqualizer.getNumberOfPresets();
    short i = 0;
    while (i < noPresets) {
        RadioButton rb = new RadioButton(this);
        rb.setText(mEqualizer.getPresetName(i));
        rgEqualizer.addView(rb, layoutParams);
        i++;
    }
}
private void loadPresetsettings() { 
    rgEqualizer.check(1);
}

似乎即使在添加子单选按钮fillRadioGroupWithRadioButtons（）之后，在radiogroup中也没有添加子项。我缺少什么/

提前致谢

Answer 1

完成一项工作我想

        RadioButton o = (RadioButton) rgEqualizer.getChildAt(1);
        o.setChecked(true);

Answer 2

您已在代码中定义了两次rgEqualizer。

    rgEqualizer = (RadioGroup) findViewById(R.id.rgEqualizerPreset);   <----- Here
    mPlayer = new MediaPlayer();
    mEqualizer = new Equalizer(0, AuID);
    rgEqualizer = new RadioGroup(this);   <---- And here //Delete this

RadioGroup.check（int）不起作用

2 个答案: