Question

我编写了一个android程序，用于从Web服务向tablerow加载值。但是一个值为null，所以我需要将它转换为字符串。有人可以告诉我这样做的方法。

try{                    

    SoapObject request = service.getRequest();
    SoapSerializationEnvelope envelope = service.getEnvelope(request);
    SoapObject response = service.getResponse(envelope);
    Log.i("Service Master", response.toString());
    int count = response.getPropertyCount();
    for (int i = 0; i < count; i++) {
        SoapObject result = (SoapObject) response.getProperty(i);
        DeleteuserDetails deleteuserDetails=new DeleteuserDetails();
        deleteuserDetails.setUserId(result.getPropertyAsString(4));
        deleteuserDetails.setUserName(result.getPropertyAsString(2));
        deleteuserDetails.setUserRole(result.getPropertyAsString(3));
        deleteuserDetails.setCreatedDate(result.getPropertyAsString(1));
        deleteuserDetails.setCreatedBy(result.getPropertyAsString(0));
        userdetail.add(deleteuserDetails);
    }

现在deleteuserDetails.setCreatedBy(result.getPropertyAsString(0));从webservice获取null值，因此我需要将其转换为字符串"null"。

logcat的：

12-20 18:48:52.608: W/System.err(2174): java.lang.NullPointerException
12-20 18:48:52.608: W/System.err(2174):     at org.ksoap2.serialization.SoapObject.getPropertyAsString(SoapObject.java:165)
12-20 18:48:52.608: W/System.err(2174):     at com.mvss.admin.Deleteuser$deteUserIdLoad.doInBackground(Deleteuser.java:81)
12-20 18:48:52.608: W/System.err(2174):     at com.mvss.admin.Deleteuser$deteUserIdLoad.doInBackground(Deleteuser.java:1)
12-20 18:48:52.608: W/System.err(2174):     at android.os.AsyncTask$2.call(AsyncTask.java:185)
12-20 18:48:52.608: W/System.err(2174):     at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
12-20 18:48:52.608: W/System.err(2174):     at java.util.concurrent.FutureTask.run(FutureTask.java:137)
12-20 18:48:52.608: W/System.err(2174):     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1068)
12-20 18:48:52.608: W/System.err(2174):     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:561)
12-20 18:48:52.608: W/System.err(2174):     at java.lang.Thread.run(Thread.java:1096)

Answer 1

使用，而不是捕获异常或放置条件的将String.valueOf（result.getPropertyAsString（0））;

它将调用参数的 toString（）方法，并将其转换为String，如果result.getPropertyAsString（0）为null，则将其更改为＆＃34;空＆＃34;

Answer 2

当属性内部为空时，

result.getPropertyAsString(0)单独将导致NPE。您的stacktrace指向SoapObject.getPropertyAsString(SoapObject.java:165)，应该是

public String getPropertyAsString(int index) {
    PropertyInfo propertyInfo = (PropertyInfo) properties.elementAt(index);
    return propertyInfo.getValue().toString();
}

source - propertyInfo或{}时会崩溃 propertyInfo.getValue()为null。

为了防止这种情况发生，您需要不是通过getPropertyAsString而是通过getProperty获取该属性，并将其手动转换为String。

您可以将其封装到某个实用程序方法

中

public static String getPropertyAsString(SoapObject object, int index) {
    Object prop = object.getProperty(index);
    if(prop instanceof PropertyInfo) {
        prop = ((PropertyInfo)prop).getValue();
    }
    return String.valueOf(prop); // will make it "null" if it is null
}

然后再做

deleteuserDetails.setUserId(getPropertyAsString(result, getPropertyAsString(4)));
deleteuserDetails.setUserName(getPropertyAsString(result, getPropertyAsString(2)));
deleteuserDetails.setUserRole(getPropertyAsString(result, getPropertyAsString(3)));

Answer 3

使用此，

try {
    deleteuserDetails.setCreatedBy(result.getPropertyAsString(0).toString());
}
catch(Exception e) {
    deleteuserDetails.setCreatedBy("null");
}

Answer 4

试试这个：

deleteuserDetails.setCreatedBy(result.getPropertyAsString(0) == null ? "null": result.getPropertyAsString(0));

Answer 5

虽然这不是一个好习惯，但你可以将空值与“”连接起来，使其成为一个字符串。

例如：

    String str=null;
    System.out.println((str+"").length()); /// prints 4

Answer 6

if(result.getPropertyAsString(0)==null)
{
deleteuserDetails.setCreatedBy("");
}
else
{
deleteuserDetails.setCreatedBy(result.getPropertyAsString(0).toString());
}

Answer 7

您只需检查其是否为null，然后为其设置字符串。

if(result.getPropertyAsString(0) == null){
 deleteuserDetails.setCreatedBy("NULL");
}else{
 deleteuserDetails.setCreatedBy(result.getPropertyAsString(0));
}

Answer 8

而不是那样，放置条件if(String!=null)。

Answer 9

"Hi this will be " + null;

在字符串

中打印出“嗨这将为空”

Answer 10

当您尝试将null值转换为String（主要是BigDecimal）时，就会出现错误

因此，您需要做的是在程序尝试将null转换为String并为String变量手动设置null值时捕获异常。

try{
    deleteuserDetails.setUserId(result.getPropertyAsString(4));
}catch (Exception e){
    deleteuserDetails.setUserId(null);
}

Answer 11

骑着小猪@prateek说的话。

public class guy
{
    public address address { get; set; }
    public int age { get; set; }

    public guy()
    {
        address = new address();
    }
}

不要使用.length进行操作，这样您实际上就可以打印出字符串

将null对象转换为String

11 个答案: