Question

我有下面的代码，使用单选按钮并获取值并将其作为函数的字符串返回。希望我可以在主程序的其他地方使用它。但是，事实并非如此。它将允许我使用变量btn，如果我通过将其声明为atl-enter而提出了final string []建议，它将返回null。大多数在线教程和stackoverflow上一个问题仅包括在onCheckedChanged中从选择的任何按钮烘烤文本。

public String listeneronbutton() {
        String btn;
        radioGroup = (RadioGroup) findViewById(R.id.radioGroup);

        radioGroup.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
            @Override
            public void onCheckedChanged(RadioGroup radioGroup, int checkedID) {
                int selectedId = radioGroup.getCheckedRadioButtonId();
                radioButton = (RadioButton) findViewById(checkedID);
                Toast.makeText(getApplicationContext(), radioButton.getText(), Toast.LENGTH_SHORT).show();
                btn = String.valueOf(radioButton.getText());      //(error here: variable 'btn' is accessed from within inner class, needs to be declared final)
            }
        });
        return btn;
}

如何正确获取函数listeneronbutton()并能够获取并返回btn值？

Answer 1

您不能拥有同时添加OnCheckedChangeListener并获得String的方法（因为职责分离和一种方法只应运行一次，另一种方法应运行得更多）。就像这样，您可以将方法instanceRadioGroup()添加到onCreate()或onCreateView()中，然后使用方法getButtonText()获得当前值。

此外，变量int checkedId已被传递到范围中，因此可以使用它。

/** the handle for the {@link RadioGroup} */
private RadioGroup mRadioGroup = null;

/** this field holds the button's text */
private String mButtonText = null;

/** the setter for the field */
protected void setButtonText(@Nullable String value) {
    this.mButtonText = value;
}

/** the getter for the field */
protected String getButtonText() {
    return this.mButtonText;
}

/** it sets mButtonText by checkedId */
protected void updateButtonText(int checkedId) {
    if ((checkedId == -1)) {
        this.setButtonText(null);
    } else {
        RadioButton radioButton = (RadioButton) this.mRadioGroup.findViewById(checkedId);
        this.setButtonText(radioButton.getText());
    }
}

/** this code should only run once, onCreate() or onCreateView() */
protected void instanceRadioGroup() {

    /* setting the handle for the {@link RadioGroup} */
    this.mRadioGroup = (RadioGroup) findViewById(R.id.radioGroup);

    /* update the field with the text of the default selection */
    int checkedId = this.mRadioGroup.getCheckedRadioButtonId();
    this.updateButtonText(checkedId);

    /* and also add an onCheckedChange listener */
    this.mRadioGroup.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
        @Override
        public void onCheckedChanged(RadioGroup radioGroup, int checkedId) {
            updateButtonText(checkedId);
        }
    });
}

Answer 2

像这样更改您的方法：

public String listeneronbutton() {
    String btn;
    RadioGroup radioGroup =(RadioGroup)findViewById(R.id.radioGroup);
    int selectedId = radioGroup.getCheckedRadioButtonId();
    radioButton = (RadioButton) findViewById(checkedID);
    Toast.makeText(getApplicationContext(), radioButton.getText(), Toast.LENGTH_SHORT).show();
    btn = String.valueOf(radioButton.getText());      

    return btn;
}

Answer 3

将String btn声明为字段。因此，您可以访问班级内部的任何地方。

public class Test{
    String btn;
    public String listeneronbutton(){

        return btn;
    }
}

Android Studio从单选按钮获取值并在其他地方使用它

3 个答案: