ParseFloat problem

[Liam O'Connor]

Hey guys,

Float.ParseFloat isnt working for me..

It builds fine with no errors but when I press the button thats used in the function, the app crashes. Ive narrowed the problem down to the

Float.parseFloat("resistorValue");

"resistorValue" is a string..
If i put a normal float value in here instead, it runs fine but once I try to extract the float it keeps crashing..Ive been at it a couple of hours now and just cant solve it..
Any ideas? Something simple no doubt..

//BAND 4 BUTTON LISTENERS
        assert band4Brown != null;
        band4Brown.setOnClickListener(new Button.OnClickListener(){

            @Override
            public void onClick(View v){
                floatResistorValue = Float.parseFloat("resistorValue");

                brownUpperTolerance = floatResistorValue * 1.01f;
                brownLowerTolerance = floatResistorValue * 0.99f;
                upperTolerance = brownUpperTolerance;
                lowerTolerance = brownLowerTolerance;
                Toast.makeText(getApplicationContext(), "Brown Selected", Toast.LENGTH_LONG).show();
            }

        });

[Paul Clapham]

Did you expect to convert that string into a float value in some way? I don't see a reasonable way of interpreting the string "resistorValue" as a float value.

On the other hand: is it possible that you have a String variable named "resistorValue" which contains a String to be interpreted as a float value? If that's the case then your code should look like this:

Float.parseFloat(resistorValue);

[Liam O'Connor]

Yeah im basically trying to get the numbers out of "resistorValue" and use them in a calculation.
I had tried

Float.parseFloat(resistorValue);

and it will build too but ends up crashing once i hit the "band4brown" button that the listener is set up for.

If i put in

floatResistorValue = 10;

it works fine..

[Tim Moores]

Whenever an app crashes, an exception stacktrace is written to the logcat. That contains the actual error message, and should be the first step when debugging app crashes. Post the full stacktrace here, and we'll try to make sense of it.

[Liam O'Connor]

Ok cool - thanks for your help..

03-26 09:00:51.092 14206-14206/com.liamoc.resistortest4 D/dalvikvm: Late-enabling CheckJNI
03-26 09:00:51.222 14206-14206/com.liamoc.resistortest4 W/dalvikvm: VFY: unable to find class referenced in signature (Landroid/view/SearchEvent;)
03-26 09:00:51.222 14206-14206/com.liamoc.resistortest4 I/dalvikvm: Could not find method android.view.Window$Callback.onSearchRequested, referenced from method android.support.v7.view.WindowCallbackWrapper.onSearchRequested
03-26 09:00:51.222 14206-14206/com.liamoc.resistortest4 W/dalvikvm: VFY: unable to resolve interface method 18813: Landroid/view/Window$Callback;.onSearchRequested (Landroid/view/SearchEvent;)Z
03-26 09:00:51.222 14206-14206/com.liamoc.resistortest4 D/dalvikvm: VFY: replacing opcode 0x72 at 0x0002
03-26 09:00:51.222 14206-14206/com.liamoc.resistortest4 I/dalvikvm: Could not find method android.view.Window$Callback.onWindowStartingActionMode, referenced from method android.support.v7.view.WindowCallbackWrapper.onWindowStartingActionMode
03-26 09:00:51.222 14206-14206/com.liamoc.resistortest4 W/dalvikvm: VFY: unable to resolve interface method 18817: Landroid/view/Window$Callback;.onWindowStartingActionMode (Landroid/view/ActionMode$Callback;I)Landroid/view/ActionMode;
03-26 09:00:51.222 14206-14206/com.liamoc.resistortest4 D/dalvikvm: VFY: replacing opcode 0x72 at 0x0002
03-26 09:00:51.822 14206-14206/com.liamoc.resistortest4 D/libEGL: loaded /system/lib/egl/libGLES_hawaii.so
03-26 09:00:51.822 14206-14206/com.liamoc.resistortest4 D/ION: config: version(0x10000) secure(0xf000) 256M(0x22d) fast(0x608) hwwr(0x608)
03-26 09:00:51.822 14206-14206/com.liamoc.resistortest4 D/MM_DEVICE: Waiting for mm thread to come up
03-26 09:00:51.832 14206-14254/com.liamoc.resistortest4 D/MM_DEVICE: mm_device_thread starting
03-26 09:00:51.842 14206-14206/com.liamoc.resistortest4 D/HAWAII_EGL: eglCreateContext() config: 18 context: 0x4fb713d8, VC context 1, Thread 14206
03-26 09:00:51.842 14206-14206/com.liamoc.resistortest4 D/HAWAII_EGL: Set SWAP INTERVAL 0
03-26 09:00:51.842 14206-14206/com.liamoc.resistortest4 D/HAWAII_EGL: eglCreateWindowSurface() surface: 0x4fb71420, VC surface: 1, Thread: 14206
03-26 09:00:51.842 14206-14206/com.liamoc.resistortest4 D/HAWAII_EGL: eglMakeCurrent(0x4fb713d8, 0x4fb71420, 0x4fb71420) Thread: 14206
03-26 09:00:51.852 14206-14206/com.liamoc.resistortest4 D/OpenGLRenderer: Enabling debug mode 0
03-26 09:01:16.306 14206-14206/com.liamoc.resistortest4 D/AndroidRuntime: Shutting down VM
03-26 09:01:16.306 14206-14206/com.liamoc.resistortest4 W/dalvikvm: threadid=1: thread exiting with uncaught exception (group=0x412bd960)
03-26 09:01:16.346 14206-14206/com.liamoc.resistortest4 E/AndroidRuntime: FATAL EXCEPTION: main
                                                                          java.lang.NullPointerException
                                                                              at java.lang.StringToReal.parseFloat(StringToReal.java:285)
                                                                              at java.lang.Float.parseFloat(Float.java:300)
                                                                              at com.liamoc.resistortest4.MainActivity$33.onClick(MainActivity.java:397)
                                                                              at android.view.View.performClick(View.java:4439)
                                                                              at android.widget.Button.performClick(Button.java:139)
                                                                              at android.view.View$PerformClick.run(View.java:18395)
                                                                              at android.os.Handler.handleCallback(Handler.java:725)
                                                                              at android.os.Handler.dispatchMessage(Handler.java:92)
                                                                              at android.os.Looper.loop(Looper.java:176)
                                                                              at android.app.ActivityThread.main(ActivityThread.java:5317)
                                                                              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)
03-26 09:01:18.939 14206-14206/com.liamoc.resistortest4 I/Process: Sending signal. PID: 14206 SIG: 9

[Tim Moores]

OK. So what value is actually being passed to the method? You can print it to the logcat via the Log class, or display it using the Toast class.

[Liam O'Connor]

assert calculate != null;
        calculate.setOnClickListener(new Button.OnClickListener(){

            @Override
            public void onClick(View v){
                resistorValue = ((band1Count + band2Count) * (band3Count) + " Ohms");
                Toast.makeText(getApplicationContext(), "Calculating...", Toast.LENGTH_LONG).show();
            }

        });

        //BAND 4 BUTTON LISTENERS
        assert band4Brown != null;
        band4Brown.setOnClickListener(new Button.OnClickListener(){

            @Override
            public void onClick(View v){
                floatResistorValue = Float.parseFloat(resistorValue);

                brownUpperTolerance = floatResistorValue * 1.01f;
                brownLowerTolerance = floatResistorValue * 0.99f;
                upperTolerance = brownUpperTolerance;
                lowerTolerance = brownLowerTolerance;
                Toast.makeText(getApplicationContext(), "Brown Selected", Toast.LENGTH_LONG).show();
            }

        });

"resistorValue" is a string made up of "band1" + "band2" * "band3".
This calculation is fine as I had it in a textView to check..

The way i'm doing it is, I select band1, then band2, then band3, then band4(tolerance), once i hit band4 it crashes, i dont get a chance to hit the calculate button id I select band4.

Could it be because i'm trying use the value in "resistorValue" in the "band4" button listener before the "calculate" button has been pressed.?

Ive tried selecting band1, band2, band3, calculate, then band4 but it still crashes once band4 is selected..

[Tim Moores]

The Toast doesn't show the actual value being parsed, so doesn't help much. And of course it needs to be done before the parsing, so you'll know which value causes the crash. No statements are executed after the app crashes.

[Paul Clapham]

                resistorValue = ((band1Count + band2Count) * (band3Count) + " Ohms");

So here you get something like "227 Ohms" or "63209776 Ohms" or... who knows? But at any rate trying to convert a string ending with "Ohms" to a float value is bound to fail.

[Liam O'Connor]

ok, i got it sorted! Thanks.

[Paul Clapham]

Liam O'Connor wrote:ok, i got it sorted! Thanks.

Hopefully that means that you noticed you were doing some arithmetic to get the resistance, then turning that number into a string, and then trying to turn the string back into a number again...

[Liam O'Connor]

I ended up just making the value a float and losing the "ohms", putting it in as a textView in the 2nd activity.

Having problems now passing the float, try'd lots of stuff but just cant get the actual value to pass.
I posted the problem as another question in this forum.

Its bloody hard work trying to figure all this stuff out, I can see why lots of people dont make it in the end - I'm trying to remain positive tho, and i appreciate all the help!
Thanks again.