I have just started learning android. I have develop a program named Android Light Sensor that measure the Intensity of Light. Here is my code:
package com.AndroidLightSensor;
import com.example.andriodlightsensor.R;
import android.os.Bundle;
import android.app.Activity;
import android.content.Context;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.view.View;
import android.widget.Button;
import android.widget.ProgressBar;
import android.widget.TextView;
import android.widget.Toast;
public class AndriodLightSensorActivity extends Activity {
ProgressBar lightMeter;
TextView textMax, textReading;
float counter;
Button read;
TextView display;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
counter = 0;
read = (Button) findViewById(R.id.bStart);
display = (TextView) findViewById(R.id.tvDisplay);
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
lightMeter = (ProgressBar)findViewById(R.id.lightmeter);
textMax = (TextView)findViewById(R.id.max);
textReading = (TextView)findViewById(R.id.reading);
SensorManager sensorManager
= (SensorManager)getSystemService(Context.SENSOR_SERVICE);
Sensor lightSensor
= sensorManager.getDefaultSensor(Sensor.TYPE_LIGHT);
if (lightSensor == null){
Toast.makeText(AndriodLightSensorActivity.this,
"No Light Sensor! quit-",
Toast.LENGTH_LONG).show();
}else{
float max = lightSensor.getMaximumRange();
lightMeter.setMax((int)max);
textMax.setText("Max Reading(Lux): " + String.valueOf(max));
sensorManager.registerListener(lightSensorEventListener,
lightSensor,
SensorManager.SENSOR_DELAY_NORMAL);
}
}
SensorEventListener lightSensorEventListener
= new SensorEventListener(){
@Override
public void onAccuracyChanged(Sensor sensor, int accuracy) {
// TODO Auto-generated method stub
}
@Override
public void onSensorChanged(SensorEvent event) {
// TODO Auto-generated method stub
if(event.sensor.getType()==Sensor.TYPE_LIGHT){
final float currentReading = event.values[0];
lightMeter.setProgress((int)currentReading);
textReading.setText("Current Reading(Lux): " + String.valueOf(currentReading));
read.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
display.setText("" + String.valueOf(currentReading));
}
});
}
}
};
}
Also The xml is:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:id="@+id/tvDisplay"
/>
<ProgressBar
android:id="@+id/lightmeter"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:padding="80dp"
style="?android:attr/progressBarStyleHorizontal"
android:max="100"
android:progress="0"
/>
<TextView
android:id="@+id/max"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
<TextView
android:id="@+id/reading"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
<Button
android:layout_width="250dp"
android:layout_height="wrap_content"
android:text="Start"
android:layout_y="249dp"
android:textSize="30dp"
android:onClick="onButtonDown"
android:id="@+id/bStart"
></Button>
</LinearLayout>
I want to get the current value whenever I press the button; i:e the value should not keep changing (Like in Stop Watch, but the updated should replace the previous one). In Eclipse, It shows no error, but when I run on my device is says" Unfortunately, Android Light Sensor has stopped." Please help!!
There are an error that is obvious.
If findViewById
is used before setContentView(R.layout.main);
the values returned are null.
When you try to use them you get an error.
Put this two lines after setContentView(R.layout.main);
read = (Button) findViewById(R.id.bStart);
display = (TextView) findViewById(R.id.tvDisplay);