无法为对象解析此符号

Question

在 OnCreate() 中创建对象 RadioGroup 时，稍后在另一个函数中调用此对象时会显示错误 "cannot resolve this symbol"

这是java代码 MainActivity.java

 @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        RadioGroup group1 = (RadioGroup)findViewById(R.id.que1_rG);
        RadioGroup group2 = (RadioGroup)findViewById(R.id.que2rG);
        RadioGroup group3 = (RadioGroup)findViewById(R.id.que3rG);
        RadioGroup group4 = (RadioGroup)findViewById(R.id.que4rG);
        RadioGroup group5 = (RadioGroup)findViewById(R.id.que5rG);
        RadioGroup group6 = (RadioGroup)findViewById(R.id.que6rG);
        RadioGroup group7 = (RadioGroup)findViewById(R.id.que7rG);
        RadioGroup group8 = (RadioGroup)findViewById(R.id.que8rG);
        RadioGroup group9 = (RadioGroup)findViewById(R.id.que9rG);
        RadioGroup group10 = (RadioGroup)findViewById(R.id.que10rG);
    }

    public void submitButton(View view)
    {
        int checkedRadio1= group1.getCheckedRadioButtonId();
        Toast.makeText(this,"Score is : " + score,Toast.LENGTH_SHORT);
        Log.v("MainActivity","Score is  " + score);
        score = 0;
    }

Answer 1

您收到无法解析符号的原因是您尚未在 class 级别声明您的 RadioGroup group1。由于您已在 onCreate 中声明和分配，因此其范围仅限于 onCreate()。要以其他方法访问，请将其设为 class 成员。

声明RadioGroup group1为class成员如下：

public class MainAcivity extends Activity{
    private RadioGroup group1;
    //Declare other RadioGroup group2,group3...group 10. if you intend
    //to access them outside of onCreate()
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        group1 = (RadioGroup)findViewById(R.id.que1_rG);
        ...
    }
      public void submitButton(View view) {
        int checkedRadio1= group1.getCheckedRadioButtonId();
        Toast.makeText(this,"Score is : " + score,Toast.LENGTH_SHORT).show();
        Log.v("MainActivity","Score is  " + score);
        score = 0;
    }
}

注：同样的事情适用于您希望在 onCreate().

之外访问的任何其他 RadioGroup

您在尝试显示 Toast 时还缺少对 show() 方法的调用。不调用 show()，不会显示 Toast 消息。

而不是

Toast.makeText(this,"Score is : " + score,Toast.LENGTH_SHORT)

使用

Toast.makeText(this,"Score is : " + score,Toast.LENGTH_SHORT).show()

Answer 2

在 class 级别声明单选按钮组。您在函数级别使用 veriable，因此您不能在函数之外使用该变量。

   private RadioGroup group1, group2, group3, group4, group5, group6, group7,group8,group9,group10;     

    @Override
            protected void onCreate(Bundle savedInstanceState) {
                super.onCreate(savedInstanceState);
                setContentView(R.layout.activity_main);
                 group1 = (RadioGroup)findViewById(R.id.que1_rG);
                 group2 = (RadioGroup)findViewById(R.id.que2rG);
                 group3 = (RadioGroup)findViewById(R.id.que3rG);
                 group4 = (RadioGroup)findViewById(R.id.que4rG);
                 group5 = (RadioGroup)findViewById(R.id.que5rG);
                 group6 = (RadioGroup)findViewById(R.id.que6rG);
                 group7 = (RadioGroup)findViewById(R.id.que7rG);
                 group8 = (RadioGroup)findViewById(R.id.que8rG);
                 group9 = (RadioGroup)findViewById(R.id.que9rG);
                 group10 = (RadioGroup)findViewById(R.id.que10rG);
            }

            public void submitButton(View view)
            {
                int checkedRadio1= group1.getCheckedRadioButtonId();
                Toast.makeText(this,"Score is : " + score,Toast.LENGTH_SHORT);
                Log.v("MainActivity","Score is  " + score);
                score = 0;
            }

无法为对象解析此符号

Cannot resolve this symbol for an Object

java

xml

android

android-radiogroup