android - 我做错了什么？错误是 Cannot invoke getText() on the primitive type double

Question

    final EditText number1 = (EditText) findViewById(R.id.editText1);
    final EditText number2 = (EditText) findViewById(R.id.editText2);
    final TextView result =(TextView) findViewById(R.id.textView3);

    Button calculate = (Button) findViewById(new View.OnClickListener() {

我做错了什么？

    public void onClick(View v) {

number1 和 number to cast double 但我收到“无法在基本类型 double 上调用 getText()”错误

    double number1 = Double.parseDouble(number1.getText().toString());//error

    double number2 = Double.parseDouble(number2.getText().toString());error         

        result.setText(String.valueOf(number1*number2));

Answer 1

改变这个

 final EditText number1 = (EditText) findViewById(R.id.editText1);
 final EditText number2 = (EditText) findViewById(R.id.editText2);

到

final EditText num1 = (EditText) findViewById(R.id.editText1);
final EditText num2 = (EditText) findViewById(R.id.editText2);

并使用

double number1 = Double.parseDouble(num1.getText().toString());
double number2 = Double.parseDouble(num2.getText().toString());

您有 EditText numberr1 和 double number1

使用 MainActivity.this.varaiblename 来引用在 onClick 之外声明和初始化的变量。

你可能想检查一下

What is variable shadowing used for in a Java class?

找到更好的解释@

question about variable scope and shadowing in java

也试一试

try
{
final EditText num1 = (EditText) findViewById(R.id.editText1);
final EditText num2 = (EditText) findViewById(R.id.editText2);
}catch(NumberFormatException e){
    e.printStacktrace();
}

如果字符串不包含可解析的 double ，则抛出 NumberFormatException。