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Android 如何避免参数可能为空_Android_Nullpointerexception - Fatal编程技术网

Android 如何避免参数可能为空

Android 如何避免参数可能为空,android,nullpointerexception,Android,Nullpointerexception,我收到一个警告参数amountTarget可能为空。有没有办法忽略这个警告 if (betid != null) { String betnumber = mData.get(i).get("betnumber"); String amountTarget = mData.get(i).get("amountTarget"); holder.tx_amount.setText(amountTarget

我收到一个警告参数amountTarget可能为空。有没有办法忽略这个警告

            if (betid != null) {
            String betnumber = mData.get(i).get("betnumber");
            String amountTarget = mData.get(i).get("amountTarget");
            holder.tx_amount.setText(amountTarget);
            holder.tx_number.setText(betnumber);
            holder.checkBox.setChecked(true);

            //getting warning argument exception on amountTarget
            int x = Integer.parseInt(amountTarget) * amountX - deductAmount; 
            holder.tx_counter.setText(x);
        }

通过执行以下操作之一,检查amountTarget是否不为null:

if(amountTarget != null){
 int x = Integer.parseInt(amountTarget) * amountX - deductAmount;
}
或者在使用变量之前将其初始化,例如

amountTarget = 0
int x = Integer.parseInt(amountTarget) * amountX - deductAmount;
或者你也可以这样做

if (amountTarget == null){
amountTarget = 0
}

请显示什么是mData?这是mData专用阵列列表mData;这是警告,但如果amountTarget为null或为空,则可能会发生此情况。所以,在通过int进行解析之前,请应用验证。为什么在ArrayList中使用hashMap?请检查它是否为null,例如ifamountTarget!=无效的