Static Value Android Studio

问题

I have two Activities. And a static integer called as counter.

So if I press a button in activity 'A' then counter = counter + 1.

Here is the code from activity a:

public static int counter = 0;
cmdOk.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
        counter = counter + 1;
        if (counter == 5)
        {
             tagihan.txtShip1.setTextColor(Color.parseColor("#000000"));
             tagihan.txtNilai1.setTextColor(Color.parseColor("#000000"));
             tagihan.txtSupir1.setTextColor(Color.parseColor("#000000"));
        }
}

And here it is from activity b :

cmdSuccess.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
        a.counter = a.counter + 1;
        if (a.counter == 5)
        {
             tagihan.txtShip1.setTextColor(Color.parseColor("#000000"));
             tagihan.txtNilai1.setTextColor(Color.parseColor("#000000"));
             tagihan.txtSupir1.setTextColor(Color.parseColor("#000000"));
        }
}

My problem is when i tried to press a button from activity a 3 times it work perfectly. So the values are 3 now.

But when i tried press a button from activity b, the value is going restart into 0. Actually i didn't destroy activity a.

So what i want is the value is going continouosly even i press from activity a or b.

Any ideas ?

Edited :

I have edit the code. Tagihan activity is what im trying to accomplished. So when the counter is 5, then tagihan activity is changing.

回答1:

Dont use static data, this is a bad approach and is not a common OOP-way to develope, instead try passing data between activities...

Act1

Intent intent = new Intent(activity2.this, activity1.class);
intent.putExtra("message", message);
startActivity(intent);

Act2:

Bundle bundle = getIntent().getExtras();
String message = bundle.getString("message");

Android development web is giving an introduction to this: http://developer.android.com/training/basics/firstapp/starting-activity.html

回答2:

After your edit, I can see that you need a "global varfiable" that can be read/write for all the activities:

Solution: All activities are embedded in an Application, so if you habe fields/members in the application you can access to them with a stadard setter/getter

you need:

Define an application

public class MyApplication extends Application {

    private int counterVariable;

    public int counterVariable() {
        return this.counterVariable;
    }

    public void setCounterVariable(int someVariable) {
        this.counterVariable = someVariable;
    }
}

add the App to the manifest:

<application 
  android:name="MyApplication" 
  android:icon="@drawable/icon" 
  android:label="@string/app_name">

Then in your activities get and set the variable like so:

// cast to Application and call the setter
((MyApplication) this.getApplication()).counterVariable(1);

// cast to Application and call the getter
int counter = ((MyApplication) this.getApplication()).getCounterVariable ();

回答3:

Please use the below code:

// Generalized form of Avoiding the Static value holding:

public class SPDataHandler {


 private Context mContext;
 private SharedPreferences mPreference;
 public SPDataHandler(Context context) {
        this.mContext = context;
        this.mPreference = mContext.getSharedPreferences("SAMPLE_SP", Context.MODE_PRIVATE);
   }
    /**
     * COMMON SETTER FOR INTEGER DATA
     */
    private void setIntegerData(String key, int value) {
        SharedPreferences.Editor editor = mPreference.edit();
        editor.putInt(key, value);
        editor.commit();
    }
    /**
     * COMMON GETTER FOR INTEGER SP DATA
     */
    private int getIntegerSpData(String key, int defaultValue) {
        return this.mPreference.getInt(key, defaultValue);
    }


    // Your Getter and Setter

     public int getmCount() {
        return this.getIntegerSpData("Count", 1);
    }

    public void setmCount(int cont) {
        this.setIntegerData("Count", cont);
    }
}

// Your Activity A

SPDataHandler handler = new  SPDataHandler(this);
int count = handler.getmCount();
cmdOk.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
        count = count + 1;
        handler.setmCount(count); // Change the logic based on your requirement
        if (count == 5)
        {
             tagihan.txtShip1.setTextColor(Color.parseColor("#000000"));
             tagihan.txtNilai1.setTextColor(Color.parseColor("#000000"));
             tagihan.txtSupir1.setTextColor(Color.parseColor("#000000"));
        }
}


// Your Activity B
SPDataHandler handler = new  SPDataHandler(this);
int count = handler.getmCount();
cmdSuccess.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
       count = count + 1;
        handler.setmCount(count); // Change the logic based on your requirement
        if (count  == 5)
        {
             tagihan.txtShip1.setTextColor(Color.parseColor("#000000"));
             tagihan.txtNilai1.setTextColor(Color.parseColor("#000000"));
             tagihan.txtSupir1.setTextColor(Color.parseColor("#000000"));
        }
}

来源：https://stackoverflow.com/questions/35354612/static-value-android-studio