I am making a simple app to use while counting a till. I am having an issue with the edit text to input the numbers.
What happens in the app is the user enters the reading of the till then the amount for each individual notes and coins and does the calculations when a button is clicked and gives you a result on a new activity.
The application crashes immediately, i believe it may be the way i am trying to get the values from the edit text.
I have supplied my code and the error log, i am new to android development so apologies if its something silly.
Thanks in advance.
TillCounter.java activity
package com.example.tillcounter;
import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class TillCounter extends Activity implements OnClickListener{
Button calcButton;
EditText readingIn, floatIn, noteIn, fiftiesIn, twentiesIn, tensIn, fivesIn, twosIn, onesIn, fiftyCentsIn, twentyCentsIn, tenCentsIn;
TextView resultOut;
//int reading = new Integer(readingIn.intValue());
double reading = Double.parseDouble(readingIn.getText().toString());
double tillFloat = Double.parseDouble(floatIn.getText().toString());
double largeNotes = Double.parseDouble(noteIn.getText().toString());
double fifties = Double.parseDouble(fiftiesIn.getText().toString());
double twenties = Double.parseDouble(twentiesIn.getText().toString());
double tens = Double.parseDouble(tensIn.getText().toString());
double fives = Double.parseDouble(fivesIn.getText().toString());
double twos = Double.parseDouble(twosIn.getText().toString());
double ones = Double.parseDouble(onesIn.getText().toString());
double fiftyC = Double.parseDouble(fiftyCentsIn.getText().toString());
double twentyC = Double.parseDouble(twentyCentsIn.getText().toString());
double tenC = Double.parseDouble(tenCentsIn.getText().toString());
double result = 0;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_till_counter);
resultOut = (TextView) findViewById(R.id.textView1);
Button calcButton = (Button) findViewById(R.id.calcButton);
calcButton.setOnClickListener(this);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.till_counter, menu);
return true;
}
@Override
public void onClick(View v) {
Log.i("clicks","You Clicked calculate");
result = (reading - tillFloat - largeNotes - fifties - twenties - tens - fives - twos - ones - fiftyC - twentyC - tenC);
if(result > 0){
resultOut.setText("The till is up by: " + result);
}else if(result < 0){
resultOut.setText("The till is down by: " + result);
}else{
resultOut.setText("The till is even at: " + reading);
}
Intent i=new Intent(TillCounter.this, ResultActivity.class);
startActivity(i);
}
}
ResultActivity.java
package com.example.tillcounter;
import android.app.Activity;
import android.os.Bundle;
import android.widget.TextView;
public class ResultActivity extends Activity{
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_display_result);
}
}
Error Log
09-03 11:56:58.033: E/Trace(19124): error opening trace file: No such file or directory (2)
09-03 11:56:58.063: W/dalvikvm(19124): threadid=1: thread exiting with uncaught exception (group=0x40d59378)
09-03 11:56:58.073: E/AndroidRuntime(19124): FATAL EXCEPTION: main
09-03 11:56:58.073: E/AndroidRuntime(19124): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.tillcounter/com.example.tillcounter.TillCounter}: java.lang.NullPointerException
09-03 11:56:58.073: E/AndroidRuntime(19124): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1995)
09-03 11:56:58.073: E/AndroidRuntime(19124): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2096)
09-03 11:56:58.073: E/AndroidRuntime(19124): at android.app.ActivityThread.access$600(ActivityThread.java:138)
09-03 11:56:58.073: E/AndroidRuntime(19124): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1207)
09-03 11:56:58.073: E/AndroidRuntime(19124): at android.os.Handler.dispatchMessage(Handler.java:99)
09-03 11:56:58.073: E/AndroidRuntime(19124): at android.os.Looper.loop(Looper.java:213)
09-03 11:56:58.073: E/AndroidRuntime(19124): at android.app.ActivityThread.main(ActivityThread.java:4787)
09-03 11:56:58.073: E/AndroidRuntime(19124): at java.lang.reflect.Method.invokeNative(Native Method)
09-03 11:56:58.073: E/AndroidRuntime(19124): at java.lang.reflect.Method.invoke(Method.java:511)
09-03 11:56:58.073: E/AndroidRuntime(19124): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:789)
09-03 11:56:58.073: E/AndroidRuntime(19124): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:556)
09-03 11:56:58.073: E/AndroidRuntime(19124): at dalvik.system.NativeStart.main(Native Method)
09-03 11:56:58.073: E/AndroidRuntime(19124): Caused by: java.lang.NullPointerException
09-03 11:56:58.073: E/AndroidRuntime(19124): at com.example.tillcounter.TillCounter.<init>(TillCounter.java:22)
09-03 11:56:58.073: E/AndroidRuntime(19124): at java.lang.Class.newInstanceImpl(Native Method)
09-03 11:56:58.073: E/AndroidRuntime(19124): at java.lang.Class.newInstance(Class.java:1319)
09-03 11:56:58.073: E/AndroidRuntime(19124): at android.app.Instrumentation.newActivity(Instrumentation.java:1053)
09-03 11:56:58.073: E/AndroidRuntime(19124): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1986)
09-03 11:56:58.073: E/AndroidRuntime(19124): ... 11 more
--------UPDATE----------- As advised by the comments below, thank you by the way, this is now my main activity and unfortunately it still crashes.
package com.example.tillcounter;
import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class TillCounter extends Activity implements OnClickListener{
Button calcButton;
EditText readingIn, floatIn, noteIn, fiftiesIn, twentiesIn, tensIn, fivesIn, twosIn, onesIn, fiftyCentsIn, twentyCentsIn, tenCentsIn;
TextView resultOut;
double reading, tillFloat, largeNotes, fifties, twenties, tens, fives, twos, ones, fiftyC, twentyC, tenC;
//int reading = new Integer(readingIn.intValue());
double result = 0;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_till_counter);
resultOut = (TextView) findViewById(R.id.results);
readingIn = (EditText) findViewById(R.id.readingIn);
floatIn = (EditText) findViewById(R.id.floatIn);
noteIn = (EditText) findViewById(R.id.notesIn);
fiftiesIn = (EditText) findViewById(R.id.fiftiesIn);
twentiesIn = (EditText) findViewById(R.id.twentiesIn);
tensIn = (EditText) findViewById(R.id.tensIn);
fivesIn = (EditText) findViewById(R.id.fivesIn);
twosIn = (EditText) findViewById(R.id.twosIn);
onesIn = (EditText) findViewById(R.id.onesIn);
fiftyCentsIn = (EditText) findViewById(R.id.fiftyCentIn);
twentyCentsIn = (EditText) findViewById(R.id.twentyCentIn);
tenCentsIn = (EditText) findViewById(R.id.tenCentIn);
Button calcButton = (Button) findViewById(R.id.calcButton);
calcButton.setOnClickListener(this);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.till_counter, menu);
return true;
}
@Override
public void onClick(View v) {
Log.i("clicks","You Clicked calculate");
//calculate();
result = (reading - tillFloat - largeNotes - fifties - twenties - tens - fives - twos - ones - fiftyC - twentyC - tenC);
if(result > 0){
resultOut.setText("The till is up by: " + result);
}else if(result < 0){
resultOut.setText("The till is down by: " + result);
}else{
resultOut.setText("The till is even at: " + reading);
}
Intent i=new Intent(TillCounter.this, ResultActivity.class);
startActivity(i);
}
public void calculate(){
reading = Double.parseDouble(readingIn.getText().toString());
tillFloat = Double.parseDouble(floatIn.getText().toString());
largeNotes = Double.parseDouble(noteIn.getText().toString());
fifties = Double.parseDouble(fiftiesIn.getText().toString());
twenties = Double.parseDouble(twentiesIn.getText().toString());
tens = Double.parseDouble(tensIn.getText().toString());
fives = Double.parseDouble(fivesIn.getText().toString());
twos = Double.parseDouble(twosIn.getText().toString());
ones = Double.parseDouble(onesIn.getText().toString());
fiftyC = Double.parseDouble(fiftyCentsIn.getText().toString());
twentyC = Double.parseDouble(twentyCentsIn.getText().toString());
tenC = Double.parseDouble(tenCentsIn.getText().toString());
}
}
and gives me the error log like this -
09-03 15:20:55.083: E/Trace(6712): error opening trace file: No such file or directory (2)
09-03 15:21:14.753: W/dalvikvm(6712): threadid=1: thread exiting with uncaught exception (group=0x40d59378)
09-03 15:21:14.763: E/AndroidRuntime(6712): FATAL EXCEPTION: main
09-03 15:21:14.763: E/AndroidRuntime(6712): java.lang.NullPointerException
09-03 15:21:14.763: E/AndroidRuntime(6712): at com.example.tillcounter.TillCounter.onClick(TillCounter.java:68)
09-03 15:21:14.763: E/AndroidRuntime(6712): at android.view.View.performClick(View.java:4147)
09-03 15:21:14.763: E/AndroidRuntime(6712): at android.view.View$PerformClick.run(View.java:17161)
09-03 15:21:14.763: E/AndroidRuntime(6712): at android.os.Handler.handleCallback(Handler.java:615)
09-03 15:21:14.763: E/AndroidRuntime(6712): at android.os.Handler.dispatchMessage(Handler.java:92)
09-03 15:21:14.763: E/AndroidRuntime(6712): at android.os.Looper.loop(Looper.java:213)
09-03 15:21:14.763: E/AndroidRuntime(6712): at android.app.ActivityThread.main(ActivityThread.java:4787)
09-03 15:21:14.763: E/AndroidRuntime(6712): at java.lang.reflect.Method.invokeNative(Native Method)
09-03 15:21:14.763: E/AndroidRuntime(6712): at java.lang.reflect.Method.invoke(Method.java:511)
09-03 15:21:14.763: E/AndroidRuntime(6712): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:789)
09-03 15:21:14.763: E/AndroidRuntime(6712): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:556)
09-03 15:21:14.763: E/AndroidRuntime(6712): at dalvik.system.NativeStart.main(Native Method)
Like you have initialised your
TextView resultOutyou should also initialise your EditTexts which you are using to get the inputs from the user likereadingIn = (EditText) findViewById(R.id.your_edit_text).Also when you are assigning the values the readingIn value is null. You can assign all the values in a method and can invoke the method at the time of calculation .