Java 为什么我在安卓系统中会出现异常
我已经编写了一个Android应用程序,它将调用RESTWeb服务。 首先,我尝试了一个Android应用程序,它的变量是固定的。我可以成功地调用Web服务 但是,当我在Android应用程序中集成GUI并在变量中赋值时,在运行时我得到以下异常:Java 为什么我在安卓系统中会出现异常,java,android,web-services,rest,method-call,Java,Android,Web Services,Rest,Method Call,我已经编写了一个Android应用程序,它将调用RESTWeb服务。 首先,我尝试了一个Android应用程序,它的变量是固定的。我可以成功地调用Web服务 但是,当我在Android应用程序中集成GUI并在变量中赋值时,在运行时我得到以下异常: java.lang.reflect.InvocationTargetException java.lang.NullPointerException 为什么我会得到例外 我的程序代码是: public class testing extends Ac
java.lang.reflect.InvocationTargetException
java.lang.NullPointerException
为什么我会得到例外
我的程序代码是:
public class testing extends Activity {
private EditText txturl,foldername,metadata,Username,Password;
private TextView textview;
private Button btnok,btncancel;
private String url,foldname,Metadata;
private String username,password;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
btnok = (Button)findViewById(R.id.btncrtfold);
btncancel=(Button)findViewById(R.id.btnreset);
btnok.setOnClickListener(new View.OnClickListener() {
public void onClick(View arg0) {
txturl=(EditText)findViewById(R.id.txturl);
Username=(EditText)findViewById(R.id.txtloginname);
Password=(EditText)findViewById(R.id.txtpassword);
foldername = (EditText)findViewById(R.id.txtfoldername);
metadata=(EditText)findViewById(R.id.txtmetadata);
foldname=foldername.getText().toString();
Metadata=metadata.getText().toString();
username=Username.getText().toString();
url=txturl.getText().toString();
password=Password.getText().toString();
//HttpRequestInterceptor preemptiveAuth=login();
String result=doprocess(url,username,password,Metadata,foldname);
textview.setText(result);
}});
}
public String doprocess(String url,String username,String password,String metadata,String fold){
HttpResponse response=null;
String content=null;
//public static void login() {
HttpRequestInterceptor preemptiveAuth = new HttpRequestInterceptor() {
@Override
public void process(HttpRequest request,
HttpContext context) throws HttpException,
IOException {
AuthState authState = (AuthState) context.getAttribute(ClientContext.TARGET_AUTH_STATE);
CredentialsProvider credsProvider = (CredentialsProvider) context.getAttribute(
ClientContext.CREDS_PROVIDER);
HttpHost targetHost = (HttpHost) context.getAttribute(ExecutionContext.HTTP_TARGET_HOST);
if (authState.getAuthScheme() == null) {
AuthScope authScope = new AuthScope(targetHost.getHostName(), targetHost.getPort());
Credentials creds = credsProvider.getCredentials(authScope);
if (creds != null) {
authState.setAuthScheme(new BasicScheme());
authState.setCredentials(creds);
}
}
}
};
DefaultHttpClient httpclient = new DefaultHttpClient();
url= url+"/"+username+"/"+foldername;
HttpPut put=new HttpPut(url);
try{
httpclient.getCredentialsProvider().setCredentials(
new AuthScope(null, -1),
new UsernamePasswordCredentials(username, password));
httpclient.addRequestInterceptor(preemptiveAuth, 0);
HttpEntity data=new StringEntity(metadata);
put.setEntity(data);
put.setHeader("Content-Type","application/vnd.org.snia.cdmi.container");
response = httpclient.execute(put);
HttpEntity resEntity=response.getEntity();
if(resEntity!=null)
content = (EntityUtils.toString(resEntity));
}catch (Exception e) {
Log.e("PUT Exception", "java.lang.NullPointerException");
}
String result=response.getStatusLine().toString()+"\n"+content;
return result;
}
您好,我认为您的doProcess方法没有返回任何内容,因此它将抛出 Textview方法的setText上的NullPointerException
请确认。如果您可以发布整个堆栈跟踪,那就太好了。在您的ip。。。实际上引发异常的代码,我怀疑是
doprocess
。嗨,levis501,我一直在编辑整个程序。我不知道。但是如果你发布了整个STACKTRACE,也许有人能找到答案。嗨,阿努普,我想是的。在我调试的程序中,结果为null并返回null。我不知道为什么你的HttpResponse还没有收到,你正在对结果进行操作。所以Http调用应该被阻塞。嗨,Anup Rojekar,我收到了响应字符串。但是我在设置字符串时出错。我可以这样设置textview中的字符串:“textview.setText(result);”是的,当然可以,请您发布您收到的确切错误消息。