【发布时间】：2015-10-13 10:22:19
【问题描述】：
在我的项目中，我在下面显示的类中得到了 nullpointerexception，我还附加了 logcat 和下面的 java 类。在这种情况下，我给出了“if（name == null）”之类的条件，我不确定它是否正确或错误如果错误意味着建议我正确的代码来解决 NPE..
提前谢谢你
public void onClick(DialogInterface dialog,int id)
{
// yes();
Intent tablewise = new Intent(Seating_Engagement.this,LoginForm.class);
startActivity(tablewise);
finish();
}
})
日志猫：
10-13 10:25:33.914 24201-24201/com.sentientit.theiWedplanner E/AndroidRuntime﹕ FATAL EXCEPTION: main
java.lang.NullPointerException
at com.sentientit.theiWedplanner.Seating_Engagement$2.onClick(Seating_Engagement.java:77)
at android.view.View.performClick(View.java:4421)
at android.view.View$PerformClick.run(View.java:18190)
at android.os.Handler.handleCallback(Handler.java:725)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:175)
at android.app.ActivityThread.main(ActivityThread.java:5279)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1102)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:869)
at dalvik.system.NativeStart.main(Native Method)
10-13 10:25:45.445 24201-24206/com.sentientit.theiWedplanner I/dalvikvm﹕ threadid=3: reacting to signal 3
10-13 10:25:45.578 24201-24206/com.sentientit.theiWedplanner I/dalvikvm﹕ Wrote stack traces to '/data/anr/traces.txt'
在第 77 行发生异常，我在下面的 java 文件中将该行标记为 (77)
Seating_Engagement
import android.app.AlertDialog;
import android.app.Dialog;
import android.app.ProgressDialog;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.view.View;
import android.widget.Button;
import com.bugsense.trace.BugSenseHandler;
import java.util.StringTokenizer;
public class Seating_Engagement extends FragmentActivity{
ProgressDialog myProgressDialog = null;
String username=welcomeuser1.usernamevalue;
String result=null;
String nameresult=null;
String Table,Chart=null;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState); BugSenseHandler.initAndStartSession(this, "68640bea");
setContentView(R.layout.seatingchart);
Button familywise=(Button)findViewById(R.id.familywise);
Button tablewisesummary=(Button)findViewById(R.id.tableclassify);
Button assignedguest=(Button)findViewById(R.id.assignedguest);
Button notassignedguest=(Button)findViewById(R.id.notassignedguest);
Button tablechair=(Button)findViewById(R.id.tableclass);
Button groupwise=(Button)findViewById(R.id.groupwise);
Button tablewise=(Button)findViewById(R.id.tablewisesummary);
Button familywisesummary=(Button)findViewById(R.id.familywisesummary);
Button groupwisesummary=(Button)findViewById(R.id.groupwisesummary);
Button arrangementsummary=(Button)findViewById(R.id.totaltables);
Button back=(Button)findViewById(R.id.back);
Button seatingoverview =(Button)findViewById(R.id.seatingview);
back.setOnClickListener(new View.OnClickListener() {
//@Override
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
finish();
}
});
seatingoverview.setOnClickListener(new View.OnClickListener() {
//@Override
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
if(username.equals("null"))
{
Dialog locationError = new AlertDialog.Builder(
Seating_Engagement.this)
.setIcon(0)
.setTitle("Message!")
.setPositiveButton(R.string.ok1,
new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog,
int id) {
// yes();
(77) Intent tablewise = new Intent(Seating_Engagement.this,LoginForm.class);
startActivity(tablewise);
finish();
}
})
.setMessage("Registered users can access this page. Click 'Yes' to login")
.setNegativeButton(R.string.no,
new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog,
int id) {
}
})
.create();
locationError.show();
}
else
{
Dialog locationError = new AlertDialog.Builder(
Seating_Engagement.this)
.setIcon(0)
.setPositiveButton("Table",
new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog,
int id) {
// yes();
Intent tablewise = new Intent(Seating_Engagement.this,
Seating_EngagementTable.class);
startActivity(tablewise);
// finish();
}
})
.setNegativeButton("Chart",
new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog,
int id) {
Intent tab=new Intent(Seating_Engagement.this,Seating_Engagementviewtable.class);
startActivity(tab);
finish();
}
})
.create();
locationError.show();
}
}
});
notassignedguest.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent tablewise=new Intent(Seating_Engagement.this,Engagement_Notyetseated.class);
startActivity(tablewise);
// finish();
}
});
assignedguest.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent tablewise=new Intent(Seating_Engagement.this,Engagement_AssignedGuest.class);
startActivity(tablewise);
//finish();
}
});
tablechair.setOnClickListener(new View.OnClickListener() {
//@Override
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
Intent tablewise=new Intent(Seating_Engagement.this,Engagement_TableClassify.class);
startActivity(tablewise);
// finish();
}
});
tablewisesummary.setOnClickListener(new View.OnClickListener() {
//@Override
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
if(username.equals("null"))
{
Dialog locationError = new AlertDialog.Builder(
Seating_Engagement.this)
.setIcon(0)
.setTitle("Message!")
.setPositiveButton(R.string.ok1,
new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog,
int id) {
// yes();
Intent tablewise = new Intent(Seating_Engagement.this,
LoginForm.class);
startActivity(tablewise);
finish();
}
})
.setMessage("Registered users can access this page. Click 'Yes' to login")
.setNegativeButton(R.string.no,
new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog,
int id) {
}
})
.create();
locationError.show();
}
else
{
Dialog locationError = new AlertDialog.Builder(
Seating_Engagement.this)
.setIcon(0)
.setPositiveButton("Table",
new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog,
int id) {
// yes();
Intent tablewise = new Intent(Seating_Engagement.this,
Engagement_TableChairSummary.class);
startActivity(tablewise);
//finish();
}
})
.setNegativeButton("Chart",
new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog,
int id) {
Intent tab=new Intent(Seating_Engagement.this,Engagement_ViewTable.class);
startActivity(tab);
finish();
}
})
.create();
locationError.show();
}
}
});
familywisesummary.setOnClickListener(new View.OnClickListener() {
//@Override
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
if(username.equals("null"))
{
Dialog locationError = new AlertDialog.Builder(
Seating_Engagement.this)
.setIcon(0)
.setTitle("Message!")
.setPositiveButton(R.string.ok1,
new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog,
int id) {
// yes();
Intent tablewise = new Intent(Seating_Engagement.this,
LoginForm.class);
startActivity(tablewise);
finish();
}
})
.setMessage("Registered users can access this page. Click 'Yes' to login")
.setNegativeButton(R.string.no,
new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog,
int id) {
}
})
.create();
locationError.show();
}
else
{
Dialog locationError = new AlertDialog.Builder(
Seating_Engagement.this)
.setIcon(0)
.setPositiveButton("Table",
new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog,
int id) {
// yes();
Intent tablewise = new Intent(Seating_Engagement.this,
Engagement_Familywisesummary.class);
startActivity(tablewise);
//finish();
}
})
.setNegativeButton("Chart",
new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog,
int id) {
Intent tab=new Intent(Seating_Engagement.this,Engagement_Familyviewtable.class);
startActivity(tab);
finish();
}
})
.create();
locationError.show();
}
}
});
groupwisesummary.setOnClickListener(new View.OnClickListener() {
//@Override
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
if(username.equals("null"))
{
Dialog locationError = new AlertDialog.Builder(
Seating_Engagement.this)
.setIcon(0)
.setTitle("Message!")
.setPositiveButton(R.string.ok1,
new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog,
int id) {
// yes();
Intent tablewise = new Intent(Seating_Engagement.this,
LoginForm.class);
startActivity(tablewise);
finish();
}
})
.setMessage("Registered users can access this page. Click 'Yes' to login")
.setNegativeButton(R.string.no,
new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog,
int id) {
}
})
.create();
locationError.show();
}
else
{
Dialog locationError = new AlertDialog.Builder(
Seating_Engagement.this)
.setIcon(0)
.setPositiveButton("Table",
new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog,
int id) {
// yes();
Intent tablewise = new Intent(Seating_Engagement.this,
Engagement_Groupwisesummary.class);
startActivity(tablewise);
//finish();
}
})
.setNegativeButton("Chart",
new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog,
int id) {
Intent tab=new Intent(Seating_Engagement.this,Engagement_Groupviewtable.class);
startActivity(tab);
finish();
}
})
.create();
locationError.show();
}
}
});
familywise.setOnClickListener(new View.OnClickListener() {
//@Override
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
// String user_url ="http://mobileapps.iwedplanner.com/mobileapps/iwedplanner/mobile/tabledisplay.aspx?unme="+username+"&occasion=Engagement";
String user_url ="http://mobileapps.iwedplanner.com/mobileapps/iwedplanner/mobile/version21/seating-table-display.aspx?unme="+username+"&occasion=Engagement";
httpclass obj = new httpclass();
result = obj.server_conn(user_url);
StringTokenizer st = new StringTokenizer(result, "|");
result = st.nextToken();
// String user ="http://mobileapps.iwedplanner.com/mobileapps/iwedplanner/mobile/Notallocated_familywise.aspx?unme="+username+"&occasion=Engagement";
String user="http://mobileapps.iwedplanner.com/mobileapps/iwedplanner/mobile/version21/notallocated_familywise.aspx?unme="+username+"&occasion=Engagement";
httpclass objg = new httpclass();
nameresult = objg.server_conn(user);
StringTokenizer s = new StringTokenizer(nameresult, "|");
nameresult = s.nextToken();
if(result.equals("There is no table"))
{
alertbox("Assignment", "None of the table has been created");
}
else if(nameresult.equals("No Guests"))
{
alertbox("Assignment", "No Guest invited");
}
else
{
boolean netvalue = false;
ConnectivityManager cm = (ConnectivityManager)getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo info = cm.getActiveNetworkInfo();
if (info != null && info.isAvailable()) {
netvalue = true;
Intent tablewise=new Intent(Seating_Engagement.this,Engagement_FamilwiseAllocation.class);
startActivity(tablewise);
// finish();
}
else
{
alertbox("Message!", "No Internet Connection!");
}
}
}
});
groupwise.setOnClickListener(new View.OnClickListener() {
//@Override
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
// String user_url ="http://mobileapps.iwedplanner.com/mobileapps/iwedplanner/mobile/tabledisplay.aspx?unme="+username+"&occasion=Engagement";
String user_url ="http://mobileapps.iwedplanner.com/mobileapps/iwedplanner/mobile/version21/tabledisplay.aspx?unme="+username+"&occasion=Engagement";
httpclass obj = new httpclass();
result = obj.server_conn(user_url);
StringTokenizer st = new StringTokenizer(result, "|");
result = st.nextToken();
// String user ="http://mobileapps.iwedplanner.com/mobileapps/iwedplanner/mobile/Not_allocated_notfamily.aspx?unme="+username+"&occasion=Engagement";
String user="http://mobileapps.iwedplanner.com/mobileapps/iwedplanner/mobile/version21/Not_allocated_notfamily.aspx?unme="+username+"&occasion=Engagement";
httpclass objg = new httpclass();
nameresult = objg.server_conn(user);
StringTokenizer s = new StringTokenizer(nameresult, "|");
nameresult = s.nextToken();
if(result.equals("There is no table"))
{
alertbox("Summary", "None of the table has been created");
}
else if(nameresult.equals("No Guests"))
{
alertbox("Assignment", "No Guest invited");
}
else
{
Intent tablewise=new Intent(Seating_Engagement.this,Engagement_GroupWiseAllocation.class);
startActivity(tablewise);
//finish();
}
}
});
tablewise.setOnClickListener(new View.OnClickListener() {
//@Override
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
if(username.equals("null"))
{
Dialog locationError = new AlertDialog.Builder(
Seating_Engagement.this)
.setIcon(0)
.setTitle("Message!")
.setPositiveButton(R.string.ok1,
new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog,
int id) {
// yes();
Intent tablewise = new Intent(Seating_Engagement.this,
LoginForm.class);
startActivity(tablewise);
finish();
}
})
.setMessage("Registered users can access this page. Click 'Yes' to login")
.setNegativeButton(R.string.no,
new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog,
int id) {
}
})
.create();
locationError.show();
}
else
{
Dialog locationError = new AlertDialog.Builder(
Seating_Engagement.this)
.setIcon(0)
.setPositiveButton("Table",
new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog,
int id) {
// yes();
Intent tablewise = new Intent(Seating_Engagement.this,
Engagement_TableWiseSummary.class);
startActivity(tablewise);
//finish();
}
})
.setNegativeButton("Chart",
new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog,
int id) {
Intent tab=new Intent(Seating_Engagement.this,Engagement_Tableviewtable.class);
startActivity(tab);
finish();
}
})
.create();
locationError.show();
}
}
});
arrangementsummary.setOnClickListener(new View.OnClickListener() {
//@Override
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
// String user_url ="http://mobileapps.iwedplanner.com/mobileapps/iwedplanner/mobile/tabledisplay.aspx?unme="+username+"&occasion=Engagement";
String user_url ="http://mobileapps.iwedplanner.com/mobileapps/iwedplanner/mobile/version21/tabledisplay.aspx?unme="+username+"&occasion=Engagement";
httpclass obj = new httpclass();
result = obj.server_conn(user_url);
StringTokenizer st = new StringTokenizer(result, "|");
result = st.nextToken();
if(result.equals("There is no table"))
{
alertbox("Summary", "None of the table has been created");
}
else
{
Intent tablewise=new Intent(Seating_Engagement.this,Engagement_TotalSeatingStatus.class);
startActivity(tablewise);
// finish();
}
}
});
}
protected void alertbox(String title, String mymessage)
{
new AlertDialog.Builder(this)
.setMessage(mymessage)
.setTitle(title)
.setCancelable(true)
.setNeutralButton(android.R.string.ok,
new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int whichButton){}
})
.show();
}
@Override
public void onStart() {
super.onStart();
// The rest of your onStart() code.
// EasyTracker.getInstance(this).activityStart(this); // Add this method.
}
@Override
public void onStop() {
super.onStop();
// The rest of your onStop() code.
// EasyTracker.getInstance(this).activityStop(this); // Add this method.
}
}
【问题讨论】：
-
而不是
username.equals("null")使用username == null -
@shayan pourvatan 通过更改用户名 == null 仍然获得相同的 NPE
标签： android android-layout android-fragments android-intent android-activity