我的问题：
1.我有错误。
2.为什么当我使用startActivity时不能转到下一页？
3.如何解决？
4.我已经通过使用Intent方法使用了startActivity
以下是证明1：
以下是证明2：
以下是证明3：
下面是代码片段：
public void OnLog(View view)
{
String Username = username.getText().toString();
String Password = password.getText().toString();
String type = "login";
if(Username.equals("") || Password.equals(""))
{
Toast.makeText(getApplicationContext(), "Please fill the Username and Password!", Toast.LENGTH_LONG).show();
}
else {
Background bg = new Background(Context, act);
bg.execute(type, Username, Password);
}
}
下面是Background.java的编码：
public class Background extends AsyncTask<String,Void,String> {
Context context;
AlertDialog alertDialog;
Background(Context ctx) {
context = ctx;
}
@Override
protected String doInBackground(String... params)
{
String type = params[0];
String login_url = "http://172.20.10.4/LoginLab3.php";
String reg_url = "http://172.20.10.4/RegisterLab3.php";
if (type.equals("login")) {
try {
String username = params[1];
String password = params[2];
URL url = new URL(login_url);
HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
httpURLConnection.setRequestMethod("POST");
httpURLConnection.setDoOutput(true);
httpURLConnection.setDoInput(true);
OutputStream outputStream = httpURLConnection.getOutputStream();
BufferedWriter bufferedWriter = new BufferedWriter(new OutputStreamWriter(outputStream, "UTF-8"));
String post_data = URLEncoder.encode("username", "UTF-8") + "=" + URLEncoder.encode(username, "UTF-8") + "&"
+ URLEncoder.encode("password", "UTF-8") + "=" + URLEncoder.encode(password, "UTF-8");
bufferedWriter.write(post_data);
bufferedWriter.flush();
bufferedWriter.close();
outputStream.close();
InputStream inputStream = httpURLConnection.getInputStream();
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream, "ISO-8859-1"));
String result = "";
String line = "";
while ((line = bufferedReader.readLine()) != null)
{
result += line;
}
bufferedReader.close();
inputStream.close();
httpURLConnection.disconnect();
return result;
}
catch (MalformedURLException e)
{
e.printStackTrace();
}
catch (IOException e)
{
e.printStackTrace();
}
}
else if(type.equals("register"))
{
try {
String name = params[1];
String surname = params[2];
String age = params[3];
String username = params[4];
String password = params[5];
URL url = new URL(reg_url);
HttpURLConnection httpURLConnection = (HttpURLConnection)url.openConnection();
httpURLConnection.setRequestMethod("POST");
httpURLConnection.setDoOutput(true);
httpURLConnection.setDoInput(true);
OutputStream outputStream = httpURLConnection.getOutputStream();
BufferedWriter bufferedWriter = new BufferedWriter(new OutputStreamWriter(outputStream, "UTF-8"));
String post_data = URLEncoder.encode("name","UTF-8")+"="+URLEncoder.encode(name,"UTF-8")+"&"
+URLEncoder.encode("surname","UTF-8")+"="+URLEncoder.encode(surname,"UTF-8")+"&"
+URLEncoder.encode("age","UTF-8")+"="+URLEncoder.encode(age,"UTF-8")+"&"
+URLEncoder.encode("username","UTF-8")+"="+URLEncoder.encode(username,"UTF-8")+"&"
+URLEncoder.encode("password","UTF-8")+"="+URLEncoder.encode(password,"UTF-8");
bufferedWriter.write(post_data);
bufferedWriter.flush();
bufferedWriter.close();
outputStream.close();
InputStream inputStream = httpURLConnection.getInputStream();
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream,"ISO-8859-1"));
String result="";
String line="";
while((line = bufferedReader.readLine())!= null)
{
result += line;
}
bufferedReader.close();
inputStream.close();
httpURLConnection.disconnect();
return result;
}
catch (MalformedURLException e)
{
e.printStackTrace();
}
catch (IOException e)
{
e.printStackTrace();
}
}
return null;
}
@Override
protected void onPreExecute()
{
alertDialog = new AlertDialog.Builder(context).create();
alertDialog.setTitle("Login Status");
}
@Override
protected void onPostExecute(String result)
{
AlertDialog.Builder dialog = new AlertDialog.Builder(context);
dialog.setTitle("Login Status");
dialog.setPositiveButton("Ok", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialogInterface, int i) {
startActivity(new Intent(Login.this, Welcome.class));
}
});
dialog.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialogInterface, int i) {
}
});
dialog.create().show();
}
@Override
protected void onProgressUpdate(Void... values)
{
super.onProgressUpdate(values);
}
}
帮我！我有一些问题。我已经使用了几乎所有方法，但无法转到下一页。为什么呢
最佳答案
活动创建代码
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Pass activity to Async Task
new Background(this).execute();
}
异步任务
public class Background extends AsyncTask<Void,Void,Void> {
private Context context;
public Background(Context context){
this.context=context;
}
@Override
protected void onPreExecute() {
super.onPreExecute();
}
@Override
protected Void doInBackground(Void... params) {
return null;
}
@Override
protected void onPostExecute(Void aVoid) {
super.onPostExecute(aVoid);
Intent intent = new Intent(context, TargetActivity.class);
context.startActivity(intent);
((Activity)context).finish();
}
}