Retrieving SharedPreferences not working in my SettingsActivity

Question

I have defined some SharedPreferences in my Main Activity (called ScoreboardActivity). The values are definitely either getting retrieved or the correct default value is working. However, I have now tried to setup a SettingsActivity screen so that the user can change these values and it isn't working correctly. When the new Activity is opening, the values aren't loading into the fields in the XML layout.

(as you will be able to tell, I'm very new to this so please be kind)

Here is my ScoreboardActivity code related to the Shared Preferences (this works):

// get the preferences
        prefs = getPreferences(MODE_PRIVATE);

        // Load the values or defaults from the SharedPreferences
        msMainClockStart = prefs.getLong( "Default_Main_Clock", 480000);    // 8 minute default
        useShotClock = prefs.getBoolean( "Use_ShotClock", false );
        msShotClockStart = prefs.getLong( "Default_Shot_Clock", 24000);     // 24 second default
        tvPeriodPrefix = prefs.getString( "Period_Prefix", getResources().getString(R.string.period) );
        valMaxPeriods = prefs.getInt( "Max_Periods", 4);


Here is my code when the menu button is pressed and Settings is clicked on (I think this is wrong but the settings.xml page does open:

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        setContentView(R.layout.settings);

        return super.onOptionsItemSelected(item);
    }

Here is my SettingsActivity:

 package com.example.ultimatescoreclock;

    import android.app.Activity;
    import android.content.SharedPreferences;
    import android.os.Bundle;
    import android.widget.CheckBox;
    import android.widget.EditText;

    public class SettingsActivity extends Activity {

    ScoreboardActivity scoreboard = new ScoreboardActivity();
    SharedPreferences settings = scoreboard.prefs;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        EditText
            strMainMinutes,
            strShotSeconds,
            strPeriodPrefix,
            strMaxPeriods;

        CheckBox
            cbUseShotClock;

        super.onCreate(savedInstanceState);
        setContentView(R.layout.settings);

        // Load the values or defaults from the SharedPreferences
        scoreboard.msMainClockStart = settings.getLong( "Default_Main_Clock", 480000);  // 8 minute default
        scoreboard.useShotClock = settings.getBoolean( "Use_ShotClock", true );
        scoreboard.msShotClockStart = settings.getLong( "Default_Shot_Clock", 24000);       // 24 second default
        scoreboard.tvPeriodPrefix = settings.getString( "Period_Prefix", getResources().getString(R.string.period) );
        scoreboard.valMaxPeriods = settings.getInt( "Max_Periods", 4);

        strMainMinutes = (EditText) findViewById(R.id.numMainMinutes);
        cbUseShotClock = (CheckBox) findViewById(R.id.cbUseShotClock);
        strShotSeconds = (EditText) findViewById(R.id.numShotSeconds);
        strPeriodPrefix = (EditText) findViewById(R.id.periodPrefix);
        strMaxPeriods = (EditText) findViewById(R.id.periodMax);


        strMainMinutes.setText( Long.toString(scoreboard.msMainClockStart / 1000) );
        cbUseShotClock.setChecked( scoreboard.useShotClock );
        strShotSeconds.setText( Long.toString(scoreboard.msShotClockStart / 1000) );
        strPeriodPrefix.setText( scoreboard.tvPeriodPrefix );
        strMaxPeriods.setText( Integer.toString(scoreboard.valMaxPeriods) );
    }


}

Here is my XML Layout:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >

<TextView
    android:id="@+id/lblMainClock"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:text="Main Clock Default (mins)" />

<EditText
    android:id="@+id/numMainMinutes"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_weight="1"
    android:ems="10"
    android:inputType="number"
    android:minEms="4" />

<CheckBox
    android:id="@+id/cbUseShotClock"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:gravity="center_vertical|start"
    android:text="Use Shot Clock" />

<TextView
    android:id="@+id/lblShotClock"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Shot Clock Default (secs)" />

<EditText
    android:id="@+id/numShotSeconds"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_weight="1"
    android:ems="10"
    android:inputType="number"
    android:minEms="4" >

    <requestFocus />
</EditText>

<TextView
    android:id="@+id/lblPeriodPrefix"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Period Prefix (e.g. Q, Shift, etc)" />

<EditText
    android:id="@+id/periodPrefix"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:ems="10" />

<TextView
    android:id="@+id/lblMaxPeriods"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Maximum Number of Periods" />

<EditText
    android:id="@+id/periodMax"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:minEms="4" />

Answer 1

You should really learn basics of android first.

The way you are instantiating ScoreboardActivity is not the android's way of instantiation of Activity.

In your code, I didn't find any code related to SAVING DATA to SharedPreferences. the code you put there is only for retrieving data from SharedPreferences in both classes.

and when you change values using UI components, like changing the CheckBox state, changing the text in EditText etc, you need to save them again to SharedPreferences while you are finalizing the value (asking user to save or finishing current Activity).

I would suggest you to read some basics of android-sdk.

• Here are some example and explanation on saving and retrieving data from SharedPreferences
• Here is an android tutorial about how to start Activity. (switching between Activities)

Answer 2

@Eric & @Adil Soomro - Thank you for your comments. You have put me on the right track and I have discovered how to accomplish the retrieving of the SharedPreferences in my SettingsActivity.

Here is my altered code for anyone that might be interested in the future...

Main Activity code retrieving the initial values:

    // get the preferences
    prefs = getPreferences(MODE_PRIVATE);

    // Load the values or defaults from the SharedPreferences
    msMainClockStart = prefs.getLong( "Default_Main_Clock", DEFAULT_MAIN_CLOCK_START);
    useShotClock = prefs.getBoolean( "Use_ShotClock", DEFAULT_USE_SHOT_CLOCK );
    msShotClockStart = prefs.getLong( "Default_Shot_Clock", DEFAULT_SHOT_CLOCK_START);
    tvPeriodPrefix = prefs.getString( "Period_Prefix", DEFAULT_PERIOD_PREFIX );
    valMaxPeriods = prefs.getInt( "Max_Periods", DEFAULT_PERIOD_MAX );

The onOptionsItemSelected method:

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    Intent intent = new Intent(this, SettingsActivity.class);       
    startActivity(intent);

    return super.onOptionsItemSelected(item);
}

The SettingsActivity class:

package com.example.ultimatescoreclock;

import android.app.Activity;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.widget.CheckBox;
import android.widget.EditText;

public class SettingsActivity extends Activity {

EditText
    strMainMinutes,
    strShotSeconds,
    strPeriodPrefix,
    strMaxPeriods;

long
    msMainClockStart,
    msShotClockStart;

int valMaxPeriods;

CheckBox cbUseShotClock;

SharedPreferences prefs;

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

    // get the Shared Preferences
    prefs  = getPreferences(MODE_PRIVATE);

    // assign the views
    strMainMinutes = (EditText) findViewById(R.id.numMainMinutes);
    cbUseShotClock = (CheckBox) findViewById(R.id.cbUseShotClock);
    strShotSeconds = (EditText) findViewById(R.id.numShotSeconds);
    strPeriodPrefix = (EditText) findViewById(R.id.periodPrefix);
    strMaxPeriods = (EditText) findViewById(R.id.periodMax);

    // Load the values or defaults from the SharedPreferences
    msMainClockStart = prefs.getLong( "Default_Main_Clock", DEFAULT_MAIN_CLOCK_START);
    cbUseShotClock.setChecked( prefs.getBoolean( "Use_ShotClock", DEFAULT_USE_SHOT_CLOCK) );
    msShotClockStart = prefs.getLong( "Default_Shot_Clock", DEFAULT_SHOT_CLOCK_START);
    strPeriodPrefix.setText( prefs.getString("Period_Prefix", DEFAULT_PERIOD_PREFIX) );
    valMaxPeriods = prefs.getInt( "Max_Periods", DEFAULT_PERIOD_MAX );

    // convert the values that need converting
    strMainMinutes.setText( Long.toString(msMainClockStart / 60000) );
    strShotSeconds.setText( Long.toString(msShotClockStart / 1000) );
    strMaxPeriods.setText( Integer.toString(valMaxPeriods) );

}

}