显示其他活动中已检查项目的数量

Question

On the second activity i have checkboxes with radiobuttons , their state i saving in sharedpreference and i want to create on first activity something like this:
" 2 from 10 checkboxes are checked "
I do not know how to do it or with what elements of the palette to do it.

Can i ask for some tricks how to do it best?

public class MainActivity extends AppCompatActivity implements CompoundButton.OnCheckedChangeListener {

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

        CheckBox cb1,cb2,cb3,cb4;
        RadioButton rb1;

        cb1 = (CheckBox)findViewById(R.id.cb1);
        cb1.setChecked(getFromSP("cb1"));
        cb1.setOnCheckedChangeListener(this);
        cb2 = (CheckBox)findViewById(R.id.cb2);
        cb2.setChecked(getFromSP("cb2"));
        cb2.setOnCheckedChangeListener(this);
        cb3 = (CheckBox)findViewById(R.id.cb3);
        cb3.setChecked(getFromSP("cb3"));
        cb3.setOnCheckedChangeListener(this);
        cb4 = (CheckBox)findViewById(R.id.cb4);
        cb4.setChecked(getFromSP("cb4"));
        cb4.setOnCheckedChangeListener(this);
        rb1 = (RadioButton)findViewById(R.id.rb1);
        rb1.setChecked(getFromSP("rb1"));
        rb1.setOnCheckedChangeListener(this);
    }


    private boolean getFromSP(String key){
        SharedPreferences preferences = getApplicationContext().getSharedPreferences("PROJECT_NAME", android.content.Context.MODE_PRIVATE);
        return preferences.getBoolean(key, false);
    }
    private void saveInSp(String key,boolean value) {
        SharedPreferences preferences = getApplicationContext().getSharedPreferences("PROJECT_NAME", android.content.Context.MODE_PRIVATE);
        SharedPreferences.Editor editor = preferences.edit();
        editor.putBoolean(key, value);
        editor.commit();
    }



    @Override
    public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
        switch(buttonView.getId()){
            case R.id.cb1:
                saveInSp("cb1",isChecked);
                break;
            case R.id.cb2:
                saveInSp("cb2",isChecked);
                break;

            case R.id.cb3:
                saveInSp("cb3",isChecked);
                break;

            case R.id.cb4:
                saveInSp("cb4",isChecked);
                break;

            case R.id.rb1:
                saveInSp("rb1",isChecked);
                break;
        }
    }
}

Now my code look like ( still no works ):

public class MainActivity extends AppCompatActivity implements CompoundButton.OnCheckedChangeListener {

    int numberOfTrue = 0;

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

        CheckBox cb1,cb2,cb3,cb4;
        Button b2;
        TextView tv1;

        b2 = (Button)findViewById(R.id.b2);

        tv1 = (TextView)findViewById(R.id.tv1);
        cb1 = (CheckBox)findViewById(R.id.cb1);
        cb1.setChecked(getFromSP("cb1"));
        cb1.setOnCheckedChangeListener(this);
        cb2 = (CheckBox)findViewById(R.id.cb2);
        cb2.setChecked(getFromSP("cb2"));
        cb2.setOnCheckedChangeListener(this);
        cb3 = (CheckBox)findViewById(R.id.cb3);
        cb3.setChecked(getFromSP("cb3"));
        cb3.setOnCheckedChangeListener(this);
        cb4 = (CheckBox)findViewById(R.id.cb4);
        cb4.setChecked(getFromSP("cb4"));
        cb4.setOnCheckedChangeListener(this);


        b2.setOnClickListener(new View.OnClickListener() {

            public void onClick(View view) {

                finish();

            }
        });

        String name = String.valueOf(numberOfTrue);
        tv1.setText(name);

    }


    private boolean getFromSP(String key){
        SharedPreferences preferences = getApplicationContext().getSharedPreferences("PROJECT_NAME", android.content.Context.MODE_PRIVATE);
        return preferences.getBoolean(key, false);
    }
    private void saveInSp(String key,boolean value) {
        SharedPreferences preferences = getApplicationContext().getSharedPreferences("PROJECT_NAME", android.content.Context.MODE_PRIVATE);
        SharedPreferences.Editor editor = preferences.edit();
        editor.putBoolean(key, value);
        editor.commit();
    }



    @Override
    public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {



        switch(buttonView.getId()){
            case R.id.cb1:
                saveInSp("cb1",isChecked);
                if (isChecked == true){
                    numberOfTrue++;
            }
                break;
            case R.id.cb2:
                saveInSp("cb2",isChecked);
                if (isChecked == true){
                    numberOfTrue++;
                }
                break;

            case R.id.cb3:
                saveInSp("cb3",isChecked);
                if (isChecked == true){
                    numberOfTrue++;
                }
                break;

            case R.id.cb4:
                saveInSp("cb4",isChecked);
                if (isChecked == true){
                    numberOfTrue++;
                }
                break;

        }
    }
}

Answer 1

You can launch the second activity with startActivityForResult() and get the callback to update the text on the first activity. More here: startActivityForResult on Android docs

Answer 2

  private void saveNumber(String key,int value) {
    SharedPreferences preferences = getApplicationContext().getSharedPreferences("PROJECT_NAME", android.content.Context.MODE_PRIVATE);
    SharedPreferences.Editor editor = preferences.edit();
    editor.putBoolean(key, value);
    editor.commit();
}

Simply save the number of trues you do if you're already using shared prefs,

in the onCheckedChanged if the boolean is true add 1 and if it's false remove 1 , and ofcourse initial at 0.