Question

我正在阅读JSONObject作为输入，我正在使用id API的getString()方法检索密钥“net.sf.json”的值但我很好奇知道为什么它不会进入if块..

INPUT:
    {
    "id" : null
    }

代码：

//reading the jsonObject from String
JSONObject jsonObject.fromObject(someString);
String id = jsonObject.getString("id");
if( id == null)
{
        //the control is not going in this if condition
}

Answer 1

在license.Validate() .AssertThat(lic => lic.ProductFeatures.Get("HardwareId") == "133456", new GeneralValidationFailure() { Message="Invalid Hardware.", HowToResolve="Contact administrator"});检查后使用optString("id",null)，当您不确定JSON格式是否相同并处理isNull()时。{/ p>

NPE

或

JSONObject jO=jsonObject.fromObject(someString);
String id = jO.optString("id",null);
if(jO.isNull("id"))
{
    //the control is not going in this if condition
}
else{

}

read this

我得net.sf.JSONObject无法强制转换为java.lang.String Exception

1 个答案: