java - How to save a checkbox state in android app

Question

I have this app with a simple checkbox which adds a line to build.prop when the user presses it , the thing works but when i exit the app the check box is reseted , is there a way to prevent this with adding a sample code in your post because i am still newbie to android apps.

MainActivity.java

package com.mythi.tests;

import java.io.DataOutputStream;
import java.io.IOException;

import android.app.Activity;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.CheckBox;
import android.widget.CompoundButton;
import android.widget.CompoundButton.OnCheckedChangeListener;

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }

    public void onCheckboxClicked(View view) {
        // Is the view now checked?
        boolean checked = ((CheckBox) view).isChecked();

        // Check which checkbox was clicked
        switch(view.getId()) {
            case R.id.checkBox1:
                if (checked){
                    try{
                        Process su = Runtime.getRuntime().exec("su");
                        DataOutputStream outputStream = new DataOutputStream(su.getOutputStream());
                        outputStream.writeBytes("cp /system/build.prop /system/build.prop.bak
");
                        outputStream.writeBytes("echo 'persist.sys.scrollingcache=3' >> /system/build.prop
");
                        outputStream.flush();

                        outputStream.writeBytes("exit
");
                        outputStream.flush();
                        su.waitFor();
                    }catch(IOException e){

                    }catch(InterruptedException e){

                    }
        }else{
            try{
                Process su = Runtime.getRuntime().exec("su");
                DataOutputStream outputStream = new DataOutputStream(su.getOutputStream());

                outputStream.writeBytes("rm -r /system/build.prop
");
                outputStream.writeBytes("mv /system/build.prop.bak /system/build.prop
");
                outputStream.flush();

                outputStream.writeBytes("exit
");
                outputStream.flush();
                su.waitFor();
            }catch(IOException e){

            }catch(InterruptedException e){

            }   
            break;
        } 

       }

   }

}

activity_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.mythi.tests.MainActivity" >

    <CheckBox
        android:id="@+id/checkBox1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="169dp"
        android:onClick="onCheckboxClicked"
        android:text="CheckBox" />

</RelativeLayout>

Answer 1

Where did you get this extremely odd approach using getRuntime().exec()? Here's an easy working code sample for you using SharedPreferences. Replace your whole switch-statement with this one:

switch(view.getId()) {
case R.id.checkBox1:
    PreferenceManager.getDefaultSharedPreferences(this).edit()
        .putBoolean("checkBox1", checked).commit();
    break;
}

Inside onCreate() add this:

CheckBox checkBox1 = (CheckBox) findViewById(R.id.checkBox1);
boolean checked = PreferenceManager.getDefaultSharedPreferences(this)
    .getBoolean("checkBox1", false);
checkBox1.setChecked(checked);

Done.