对于参数类型 double、EditText，运算符 * 未定义
我真的不知道为什么会出现这个错误。这可能很简单，但我对此很陌生。
final Button calculate = (Button) findViewById(R.id.calculate);
calculate.setOnClickListener(new View.OnClickListener() {
// Implement the OnClickListener callback
private void onClick(Button calculate) {
double perimeter = 2 * (Math.PI * entry); //error on this line
System.out.print(perimeter);
}
public void onClick(View v) {
// TODO Auto-generated method stub
}
}
);
I'm really not sure why I get this error. It's probably something simple but I'm new to this.
final Button calculate = (Button) findViewById(R.id.calculate);
calculate.setOnClickListener(new View.OnClickListener() {
// Implement the OnClickListener callback
private void onClick(Button calculate) {
double perimeter = 2 * (Math.PI * entry); //error on this line
System.out.print(perimeter);
}
public void onClick(View v) {
// TODO Auto-generated method stub
}
}
);
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看来
entry是一个EditText对象......你不能将其相乘。我将做出一个有根据的猜测，您想要将
EditText中的内容相乘。查看javadocs，您需要使用entry.getText().toString()获取文本，并将其转换为数字类型（前提是文本表示数字类型）。（或者
Integer.parseInt()如果这就是您所期望的）http://developer.android.com/reference/android/widget/EditText.html
http://docs.oracle.com/javase/6 /docs/api/java/lang/Double.html
http://docs.oracle.com/javase/6 /docs/api/java/lang/Integer.html
It would appear that
entryis anEditTextobject ... you can't multiply that.I'm going to make an educated guess that you want to multiply what's in that
EditText. Looking at the javadocs, You need to get the text withentry.getText().toString(), and convert it to a numeric type (provided the text represents a numeric type).(or
Integer.parseInt()if that's what you're expecting)http://developer.android.com/reference/android/widget/EditText.html
http://docs.oracle.com/javase/6/docs/api/java/lang/Double.html
http://docs.oracle.com/javase/6/docs/api/java/lang/Integer.html