CODEWITHSUNDEEP
androidandroid-fragments
Django
Django

Reputation: 135

How to retain variable values in a fragment so when the fragment is launched again the value persists?

I'm making a step counting app that uses navigationview to navigate between different parts of the application and I'm using a fragment for each view, I've setup the Sensor code with a fragment and I store the value in a variable but every time I navigate to another fragment the value of step count is lost and starts from zero. I want the value to remain when I navigate between the different fragments. 

import android.app.Fragment;
import android.content.Context;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.RelativeLayout;
import android.widget.TextView;

public class HomeFragment extends Fragment implements SensorEventListener {

SensorManager sensorManager;
TextView tv_steps;
boolean running = false;
View myView;

int initialStepCount = 0;
int stepCount = 0;

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    myView = inflater.inflate(R.layout.home_layout, container, false);

    // null pointer exception
    // la fragmenta chon view agarrenitawa and make sure null nia

    RelativeLayout rl = (RelativeLayout) inflater.inflate(R.layout.home_layout, container, false);
    tv_steps = (TextView) rl.findViewById(R.id.tv_steps);
    sensorManager = (SensorManager) getActivity().getSystemService(Context.SENSOR_SERVICE);

    return rl;
}

@Override
public void onResume() {
    super.onResume();
    running = true;
    Sensor countSensor = sensorManager.getDefaultSensor(Sensor.TYPE_STEP_COUNTER);
    if (countSensor != null) {
        sensorManager.registerListener(this, countSensor, SensorManager.SENSOR_DELAY_FASTEST);
    } else {
    }
}

@Override
public void onPause() {
    super.onPause();
    running = false;
    // unregister
    //sensorManager.unregisterListener(this);
}

@Override
public void onSensorChanged(SensorEvent event) {
    if (initialStepCount == 0) {
        initialStepCount = (int) event.values[0];
    }

    stepCount = (int)event.values[0] - initialStepCount;

    if (running) {
        tv_steps.setText(String.valueOf(stepCount));

    }
}

@Override
public void onAccuracyChanged(Sensor sensor, int accuracy) {

}
}

Upvotes: 0

Views: 1650

Answers (4)

Pritam Rajput
Pritam Rajput

Reputation: 118

You can use shared preference to store values.

SharedPreferences sharedpreferences=context.getSharedPreferences("MyPrefs", context.MODE_PRIVATE);


    public String getPreference(String name){ 
            Map<String, ?> reader = sharedpreferences.getAll();
            if(reader.get(name).toString()!= null){
                return reader.get(name).toString();
            }
            return null;
        }

        public void setPreference(String name,String value){
            SharedPreferences.Editor editor = sharedpreferences.edit();
            editor.remove(name);
            editor.putString(name,value);
            editor.commit();

        }

Upvotes: 0

Ram
Ram

Reputation: 1534

Simple solution: Declare step count variables as static.

Efficient solution: Use onSaveInstanceState(Bundle) method to save the value and retrieve it in onCreate(Bundle) method next time.

Upvotes: 1

Bj&#246;rn Kechel
Bj&#246;rn Kechel

Reputation: 8463

save your values like this:

@Override
public void onSaveInstanceState(Bundle outState) {
    outState.putInt(SOME_KEY, someIntValue);
    super.onSaveInstanceState(outState);
}

and restore them like this:

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    someIntValue = savedInstanceState.getInt(SOME_KEY)

Upvotes: 0

Shrikant
Shrikant

Reputation: 257

You can use saveInstance for restoring variable value ,and if you are setting that value to any TextView , TextView can save its state by using freezesText attribute:

<TextView
    ...
    android:freezesText="true"/>

For documentation about freezesText : https://developer.android.com/reference/android/widget/TextView.html#attr_android:freezesText

Upvotes: 0

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