How to handle onClickListener in android?

0
votes

I am trying to write a simple android application to help interpret some lab results.

package org.android.bloodgas;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.TextView;
import android.widget.Button;

public class pinit extends Activity {


    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        Button interpretButton = (Button) findViewById(R.id.Interpret);

        //interpretButton.setOnClickListener(this);
        View.OnClickListener myhandler = new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                    float inpPH, inpPO2, inpPCO2, inpHCO3, inpBE;
                    inpPH = Float.valueOf(findViewById(R.id.InpPH).toString()).floatValue();
                    inpPO2 = Float.valueOf(findViewById(R.id.InpO2).toString()).floatValue();
                    inpPCO2 = Float.valueOf(findViewById(R.id.InpCO2).toString()).floatValue();
                    inpHCO3 = Float.valueOf(findViewById(R.id.InpHCO3).toString()).floatValue();
                    inpBE = Float.valueOf(findViewById(R.id.InpBE).toString()).floatValue();

                    TextView interpretation;
                    interpretation = (TextView) findViewById(R.id.Interpretation);

                    String sResult = null;
                    if (inpPH < 7.35) {
                        // Acidosis
                        sResult.concat("Acidosis. ");
                    } else {
                        if (inpPH > 7.45) {
                            // Alkalosis
                            sResult.concat("Alkalosis. ");
                        } else {
                            // Normal acidity, 7.35-7.45
                            sResult.concat("Normal pH. ");
                        }
                    }
                    interpretation.setText(sResult);
            }
        };

        interpretButton.setOnClickListener(myhandler);

    }

}

It does compile and run but when I press on the "interpret" button it simply says The application ... has stopped unexpectedly. Please try again. (Force Close).

I am totally new to android programming... So I guess this would be some very stupid mistake I have made but please help. Thanks.

update: changed the code to this (minus the logic portion while i will complete later) but still hangs when press on the button.

package org.android.bloodgas;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.Button;

public class Pinit extends Activity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        Button interpretButton = (Button) findViewById(R.id.Interpret);

        View.OnClickListener myhandler = new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                    float inpPH, inpPO2, inpPCO2, inpHCO3, inpBE;
                    inpPH = Float.valueOf(((EditText) Pinit.this.findViewById(R.id.InpPH)).toString()).floatValue();
                    inpPO2 = Float.valueOf(((EditText) Pinit.this.findViewById(R.id.InpO2)).toString()).floatValue();
                    inpPCO2 = Float.valueOf(((EditText) Pinit.this.findViewById(R.id.InpCO2)).toString()).floatValue();
                    inpHCO3 = Float.valueOf(((EditText) Pinit.this.findViewById(R.id.InpHCO3)).toString()).floatValue();
                    inpBE = Float.valueOf(((EditText) Pinit.this.findViewById(R.id.InpBE)).toString()).floatValue();
                    // ...
            }
        };

        interpretButton.setOnClickListener(myhandler);

    }

}

logcat:

12-07 03:37:02.231: WARN/dalvikvm(1074): threadid=1: thread exiting with uncaught exception (group=0x4001d800)
12-07 03:37:02.332: ERROR/AndroidRuntime(1074): FATAL EXCEPTION: main
12-07 03:37:02.332: ERROR/AndroidRuntime(1074): java.lang.NumberFormatException: android.widget.EditText@44f47e60
12-07 03:37:02.332: ERROR/AndroidRuntime(1074):     at org.apache.harmony.luni.util.FloatingPointParser.initialParse(FloatingPointParser.java:130)
12-07 03:37:02.332: ERROR/AndroidRuntime(1074):     at org.apache.harmony.luni.util.FloatingPointParser.parseFloat(FloatingPointParser.java:319)
12-07 03:37:02.332: ERROR/AndroidRuntime(1074):     at java.lang.Float.parseFloat(Float.java:291)
12-07 03:37:02.332: ERROR/AndroidRuntime(1074):     at java.lang.Float.valueOf(Float.java:330)
12-07 03:37:02.332: ERROR/AndroidRuntime(1074):     at org.android.bloodgas.Pinit$1.onClick(Pinit.java:22)
12-07 03:37:02.332: ERROR/AndroidRuntime(1074):     at android.view.View.performClick(View.java:2408)
12-07 03:37:02.332: ERROR/AndroidRuntime(1074):     at android.view.View$PerformClick.run(View.java:8816)
12-07 03:37:02.332: ERROR/AndroidRuntime(1074):     at android.os.Handler.handleCallback(Handler.java:587)
12-07 03:37:02.332: ERROR/AndroidRuntime(1074):     at android.os.Handler.dispatchMessage(Handler.java:92)
12-07 03:37:02.332: ERROR/AndroidRuntime(1074):     at android.os.Looper.loop(Looper.java:123)
12-07 03:37:02.332: ERROR/AndroidRuntime(1074):     at android.app.ActivityThread.main(ActivityThread.java:4627)
12-07 03:37:02.332: ERROR/AndroidRuntime(1074):     at java.lang.reflect.Method.invokeNative(Native Method)
12-07 03:37:02.332: ERROR/AndroidRuntime(1074):     at java.lang.reflect.Method.invoke(Method.java:521)
12-07 03:37:02.332: ERROR/AndroidRuntime(1074):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
12-07 03:37:02.332: ERROR/AndroidRuntime(1074):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
12-07 03:37:02.332: ERROR/AndroidRuntime(1074):     at dalvik.system.NativeStart.main(Native Method)
12-07 03:37:02.382: WARN/ActivityManager(68):   Force finishing activity org.android.bloodgas/.Pinit
12-07 03:37:02.952: WARN/ActivityManager(68): Activity pause timeout for HistoryRecord{44fbfc90 org.android.bloodgas/.Pinit}
12-07 03:37:07.761: INFO/Process(1074): Sending signal. PID: 1074 SIG: 9
12-07 03:37:09.852: INFO/ActivityManager(68): Process org.android.bloodgas (pid 1074) has died.
12-07 03:37:09.862: INFO/WindowManager(68): WIN DEATH: Window{44fa71e0 org.android.bloodgas/org.android.bloodgas.Pinit paused=false}
12-07 03:37:15.931: WARN/ActivityManager(68): Activity destroy timeout for HistoryRecord{44fbfc90 org.android.bloodgas/.Pinit}
2
androidnullpointerexception
You'll need to post a stacktrace from your logcat for us to be able to give you any help. – Falmarri
update 2: Turns out that the culprit is not on the click handler. It is the type conversion problem. It turns out that the string value of EditText is requested via .getText() not .toString(). My stupid mistake. – bubu

2 Answers

3
votes

First thing I see is that you have to cast this to the type of view that it is

inpPH = Float.valueOf(findViewById(R.id.InpPH).toString()).floatValue();

Second, you're calling this from within the onclickListener. So findViewById() really shouldn't even compile. You need

inpPH = Float.valueOf((TypeOfView) pinit.this.findViewById(R.id.InpPH).toString()).floatValue();

And also in java, classes should start with capital lettors, so it should be

public class Pinit extends Activity{

Update:

findViewById(R.id.InpPH) resolves to EditTex

No it doesn't. It resolves to a View. Calling .toString() on a view is not what you want. You want to do

((EditText) pinit.this.findViewById(R.id.InpPH)).getText().toString()
1
votes

I guess you get NumberFormatException at one of the calls like this:

Float.valueOf(findViewById(R.id.InpPH).toString())

As to the doc the NumberFormatException is got if string is null, has a length of zero or can not be parsed as a float value.

However, checking the logCat trace for this would give a clean answer.