How to keep a TextView's content when changing the Activity

Question

I'm pretty new to Android Development and I've come across a problem with my TextView. I have an XML file that contains a ScrollView and a TextView:

<ScrollView
    android:id="@+id/scroll1"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fillViewport="true" >

            <TextView 
                android:id="@+id/textView"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:freezesText="true">
            </TextView>

    </ScrollView>

And I have included it in two different XML files

<LinearLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent"
  android:orientation="vertical">

<LinearLayout 
    android:layout_width="fill_parent"
    android:layout_height="0dp"
    android:layout_weight="1"
    android:orientation="vertical">

    <include
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1"
        android:id="@+id/story_view"
        layout="@layout/story_view" />

    <EditText 
        android:id="@+id/editText1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="@string/add_text">
    </EditText>

</LinearLayout>

<LinearLayout 
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal">

    <Button android:text="@string/end_button"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:layout_width="0dp"
        android:onClick="endButtonPressed">
    </Button>

    <Button android:text="@string/submit_button"
        android:layout_height="wrap_content"
        android:layout_width="0dp"
        android:layout_weight="1"
        android:onClick="textAdded">
    </Button>

</LinearLayout>

and

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical">

<LinearLayout 
    android:layout_width="fill_parent"
    android:layout_height="0dp"
    android:layout_weight="1"
    android:orientation="vertical">

    <include
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        layout="@layout/story_view" />

</LinearLayout>

<LinearLayout
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal" >

    <Button android:text="@string/save"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:layout_width="0dp"
        android:onClick="saveToDevice">
    </Button>

    <Button android:text="@string/facebook"
        android:layout_height="wrap_content"
        android:layout_width="0dp"
        android:layout_weight="1"
        android:onClick="saveToFacebook">
    </Button>

</LinearLayout>

But when I go from the first XML file to the other (and changing the Activity in the process), the content of the TextView disappears. I have tried freezesText but that doesn't seem to work.

Ordinarily I would just pass the content in an intent but my text is in different colours and I want to maintain that.

I could pass a Bitmap image in an intent but I want to avoid that if possible.

Thanks.

Answer 1

You could use the Activity state to save some values like

@Override
public void onSaveInstanceState(Bundle savedInstanceState) {
    super.onSaveInstanceState(savedInstanceState);
    // Save UI state changes to the savedInstanceState.
    // This bundle will be passed to onCreate if the process is
    // killed and restarted.
    savedInstanceState.putBoolean("MyBoolean", true);
    savedInstanceState.putDouble("myDouble", 1.9);
    savedInstanceState.putInt("MyInt", 1);
    savedInstanceState.putString("MyString", "Welcome back to Android");
}

@Override
public void onRestoreInstanceState(Bundle savedInstanceState) {
    super.onRestoreInstanceState(savedInstanceState);
    // Restore UI state from the savedInstanceState.
    // This bundle has also been passed to onCreate.
    boolean myBoolean = savedInstanceState.getBoolean("MyBoolean");
    double myDouble = savedInstanceState.getDouble("myDouble");
    int myInt = savedInstanceState.getInt("MyInt");
    String myString = savedInstanceState.getString("MyString");
}

Answer 2

That happen because when you come back to the first activity, the onCreate method is called, so your textView is a new textView. Take a look to Activity Lifecycle, here is explained much better.

You can use sharedPreferences or a Singleton (a design pattern), where the class can be instantiate only one time:

public class MySingleton{

    private static MySingleton INSTANCE = null;
    private String textViewInformation;

    private MySingleton() {

    }

    public static MySingleton getInstance(Context context) {
        synchronized (MySingleton.class) {
            if (INSTANCE == null) {
                synchronized (MySingleton.class) {
                    if (INSTANCE == null)
                        INSTANCE = new MySingleton();
                }
            }
        }
        return INSTANCE;
    }

  public String getTextViewInformation(){
    return textViewInformation;
  }

 public void setTextViewInformation(String textViewInfo){
  textViewInformation = textViewInfo;
 }

}

and then:

 public void onDestroy() {
            super.onDestroy();
      MySingleton.getInstance(this).setTextViewInformation("textViewText");
     }



  public void onResume() {
            super.onResume();

   if(MySingleton.getInstance(this).getTextViewInformation() != null){
     yourTextView.setText(MySingleton.getInstance(this).getTextViewInformation());
   }else{
     yourTextView.setText("new text");
   }

Maybe this way it's longer than the shared preferences, but it's very useful. Excuse my bad english! I hope this help.

Answer 3

you can use the sharedpreferences for this purpose it allows you to store and retrieve data using key-value pairs. for satisfying your purpose you need to store your activity state in sharedpreferences.

particularly in your case first you need to store the textview value in shared preferences when you destroy the activity

@Override
        public void onDestroy() {
            super.onDestroy();
TextView tvText = (TextView) findViewById(R.id.yourelement);
            SharedPreferences.Editor prefEditor = getSharedPreferences("Preferences", Context.MODE_PRIVATE).edit();
            prefEditor.putBoolean("text", tvText .getText().toString());
            prefEditor.commit();
        }

Then in onCreate you need to set the textview text from your shared preferences.

TextView tvText = (TextView) findViewById(R.id.yourelement);
    SharedPreferences prefs = getSharedPreferences("Preferences", Context.MODE_PRIVATE);
    if (prefs.contains("text")){
            tvText .setText(prefs.getString("text", ""));
        }