Android：Java不能引用非final变量

Android: Java cannot refer to a non-final variable

在我的Android应用程序中，当用户单击Sales按钮时，它将显示另一个视图来执行销售。

如果所选客户的GST许可证到期日期少于7天并且即将到期，则在实施警报对话框之前，我的应用程序工作正常，没有任何问题，向用户显示警告消息。现在，如果我不向这两个变量(customer和v声明final的话，我会收到以下错误消息。

Cannot refer to a non-final variable customer inside an inner class defined in a different method

Cannot refer to a non-final variable v inside an inner class defined in a different method

我明白

The reference declared as final cannot be modified once it is
initialized.

那么，如果我把这两个变量指定为final，会发生什么？它总是包含相同的值？有人能给我解释一下为什么编译器会给我这些错误，为什么我要向这两个变量声明final？

这是我的源代码：

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private OnClickListener salesBtnClick = new OnClickListener() {
@Override
public void onClick(View v) {
Customer customer = salesCustAdpt.getSelectedCustomer();
if (customer != null) {
Date expiryDate = customer.getGSTLicenseExpiryDate();
if (checkCustomerGSTLicenseExpiryDate(expiryDate)) {
AlertDialog.Builder builder = new AlertDialog.Builder(SalesCustomerActivity.this);
builder.setCancelable(false)
.setPositiveButton(
"OK",
new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
try {
//Perform sales here!
Intent intent = null;
intent = new Intent(v.getContext(), SalesActivity.class);//Error msg here!
Bundle bundle = new Bundle();
bundle.putSerializable("selCustomer", customer);//Error msg here!
intent.putExtra("bundle", bundle);
startActivity(intent);
finish();
} catch (Exception ex) {
AddPlusUtil.displayErrorMsg(
SalesCustomerActivity.this,
ex);
}
}
});

AlertDialog alert = builder.create();
alert.setTitle("Warning Message");
String errMsg ="GST License Expiry Date of selected customer is
" + expiryDate +" and going to expire soon.";
alert.setMessage(errMsg);
alert.setIcon(android.R.drawable.stat_notify_error);
alert.show();
} else {
//Perform Sales
}
}
}
}

定义客户时，使用final:

1	final Customer customer = salesCustAdpt.getSelectedCustomer();

另外，在onclick方法中，将视图设置为final：

1	public void onClick(final View v) {

希望这有帮助：)