在Java中检查对象的NULL的最佳方法 [英] Best way to check NULL for objects in Java

问题描述

我有一个检查NULL 从对象中提取的值的解决方案，但是我觉得可能有比我在这里做的更好的方法。所以请用代码片段向我建议最佳方式：）

I have a solution to check NULL values extracted from object, However i feel there might be best approach than i am doing here. So please suggest me the best ways with code snippet :)

我将把我的xml内容传递给解组方法&然后将unmarshalledValues传递给null检查方法（即ValidateInputFiled）

I will be passing my xml Content to unmarshalling method & then pass the unmarshalledValues to null check method (i.e ValidateInputFiled )

Contents unmarshalledValues = unmarshalingContent( xml ); 
inputCheck = ValidateInputField( unmarshalledValues );

我的XML元素有一个POJO，如下所述，

I have a POJO for my XML elements as mentioned below,

 @XmlRootElement( name = "contents" )
    public class Contents
    {
        @XmlElement
        String A;

        @XmlElement
        String B;

        @XmlElement
        String C;

        @XmlAttribute
        String D;

       public String getA()
      {
        return A;
      }

       public String getB()
      {
        return B;
      }

       public String getC()
      {
        return C;
      }

       public String getD()
      {
        return D;
      }
}

我已经定义了ValidateInputFiled，如下所述

I have defined ValidateInputFiled as mentioned below

public Boolean ValidateInputField( Contents unmarshalledValues )
    {
        int checker = 0;
        Boolean listCheck = false;

        // Extracting unmarshalled values from xml
        String A= unmarshalledValues.getA();
        String B= unmarshalledValues.getB();
        String C = unmarshalledValues.getC();
        String D= unmarshalledValues.getD();

        if ( A== null || A.isEmpty() )
        {
            checker++;
        }

        if ( B== null || B.isEmpty() )
        {
            checker++;
        }

        if ( C== null || C.isEmpty() )
        {
            checker++;
        }

        if ( D== null || D.isEmpty() )
        {
            checker++;
        }

        if ( checker == 0 )
        {
            listCheck = true;
        }

        return listCheck;

    }

这里我希望避免对每个字符串值进行NULL检查（即A，B，C，D）我可以使用集合或列表对内容或unmarshalledValues进行空检查吗？

Here i am looking to avoid NULL check for each String Values ( i.e A, B, C, D ) instead can i just do null check for Contents or for unmarshalledValues using collection or list ?

推荐答案

<那是你在找什么？

public Boolean ValidateInputField(Contents unmarshalledValues) {
    // Extracting unmarshalled values from xml
    String A = unmarshalledValues.getA();
    String B = unmarshalledValues.getB();
    String C = unmarshalledValues.getC();
    String D = unmarshalledValues.getD();
    return checkNull(A, B, C, D);
}

private static boolean checkNull(String... strings) {
    for (String string : strings) {
        if (string == null || string.isEmpty()) {
            return false;
        }
    }
    return true;
}

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