后退按钮未调用onActivityResult

Question

I'm having an issue with my "back button" on my android app. I have an Activity called DashboardActivity that calls AskQuestionActivity. I pass a value to AskQuestionActivity, and want to send that value back to DashboardActivity when the back button is pressed. This is my code so far. The child class is:

public class AskQuestionActivity extends AppCompatActivity {

private int userId;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.ask_question);
    setUserId(getIntent().getExtras().getInt("id"));
}

@Override
public void onBackPressed() {
    Intent resultData = getIntent();
    resultData.putExtra("id", getUserId());
    setResult(2, resultData);
    finish();
//    super.onBackPressed();
 }

public int getUserId() {
    return userId;
}

public void setUserId(int userId) {
    this.userId = userId;
}

}

The parent class is:

public class DashboardActivity extends AppCompatActivity {

    private int userId;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.dashboard);
        setUserId(getIntent().getExtras().getInt("id"));
        DisplayMetrics dm = this.getResources().getDisplayMetrics();

        RelativeLayout linearLayout = (RelativeLayout) findViewById(R.id.dashboard);

        TextView availableQuestions = new TextView(this);
        RelativeLayout.LayoutParams relativeLayout = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.WRAP_CONTENT, RelativeLayout.LayoutParams.WRAP_CONTENT);
        relativeLayout.setMargins(convertDpToPx(100,dm), convertDpToPx(40,dm), convertDpToPx(0,dm), convertDpToPx(0, dm));
        availableQuestions.setLayoutParams(relativeLayout);
        User u = getUser(this.userId);

        if (u.getAvailableQuestionCount() > 0) {
            availableQuestions.setTextColor(Color.GREEN);
        } else {
            availableQuestions.setTextColor(Color.RED);
        }
        availableQuestions.setText("" + u.getAvailableQuestionCount());
        linearLayout.addView(availableQuestions);
    }

    public void askQuestion(View view) {
        Intent intent = new Intent(this, AskQuestionActivity.class);
        intent.putExtra("id", getUserId());
        startActivityForResult(intent, 2);
    }

    /**
     * gets the logged in user and populates the entity
     * @return
     */
    private User getUser(int id) {
        MySQLiteHelper mDbHelper = new MySQLiteHelper(getApplicationContext());
        SQLiteDatabase db = mDbHelper.getWritableDatabase();
        String[] selectionArgs = {String.valueOf(id)};
        Cursor cursor = db.query("user", null, "id=?", selectionArgs, null, null, null, null);
        User u = new User(new Long(id));

        if (cursor.moveToFirst()) {
            u.setUsername(cursor.getString(cursor.getColumnIndex("username")));
            u.setPassword(cursor.getString(cursor.getColumnIndex("password")));
            u.setAvailableQuestionCount(Integer.parseInt(cursor.getString(cursor.getColumnIndex("availableQuestionsCount"))));
            u.setAnswerCount(Integer.parseInt(cursor.getString(cursor.getColumnIndex("answerCount"))));
        } else {
            return null;
        }
        return u;
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (requestCode == RESULT_OK) {
            Intent intent = getIntent();
            setUserId(data.getIntExtra("id", 0));
        }
    }
        /**
         * getter for userId
         * @return
         */
    public int getUserId() {
        return userId;
    }

    /**
     * setter for userId
     * @param userId
     */
    public void setUserId(int userId) {
        this.userId = userId;
    }

    private int convertDpToPx(int dp, DisplayMetrics displayMetrics) {
        float pixels = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, dp, displayMetrics);
        return Math.round(pixels);
    }

    }

and my manifest file is:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.amk27.pollit" >

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme" >
        <activity
            android:name=".MainActivity"
            android:label="@string/app_name"
            android:theme="@style/AppTheme.NoActionBar" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <activity
            android:name=".CreateAccountActivity"
            android:label="CreateAccountActivity"
            android:parentActivityName=".MainActivity" >
            <meta-data
                android:name="android.support.PARENT_ACTIVITY"
                android:value=".MainActivity" />
        </activity>

        <activity
            android:name=".DashboardActivity"
            android:label="DashboardActivity"
            android:parentActivityName=".MainActivity" >
            <meta-data
                android:name="android.support.PARENT_ACTIVITY"
                android:value=".MainActivity" />
        </activity>

        <activity
            android:name=".AskQuestionActivity"
            android:label="AskQuestionActivity"
            android:parentActivityName=".DashboardActivity" >
            <meta-data
                android:name="android.support.PARENT_ACTIVITY"
                android:value=".DashboardActivity" />
        </activity>

    </application>

</manifest>

The problem seems to be that in the parent class, onActivityResult is never called. onCreate seems to be called instead. I'm not sure what is causing this, so if anyone could shed some light on the situation, I would greatly appreciate it.

Thanks!

Answer 1

        startActivityForResult(intent, 1);

        setResult(Activity.RESULT_OK, resultData);

Activity.RESULT_OK is 1? because when you start activity for result, you set your request code to 1

Answer 2

maybe you can use

 startActivityForResult(intent,code)

@Override  
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {  
        // TODO Auto-generated method stub 
         user.setName(data.getStringExtra("name"))
        Toast.makeText(this, data.getStringExtra("name"), 1).show();
        super.onActivityResult(requestCode, resultCode, data);  
    } 

Answer 3

The issue was that I was confusing the up button with the back button. I didn't realize the difference. After reading about the 2, the problem became clear. onActivityResult works for the back button, as many of you pointed out, but for the up button, you need to use onOptionsItemSelected(MenuItem item).