Display back button of action bar is not going bac

问题:

I am developing an Android app. I am using ActionBar with AppCompactActivity. In my app, I add back button to action bar. But when I click on it, it is not going back to the previous activity. For example, I start activity 2 from activity 1. Activity 2 contains action bar with back button. But when I click on action bar back button of activity 2, it is not going back to activity 1.

This is how I set action bar for activity 2:

public class EditProfileActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.edit_profile);
        Toolbar toolbar = (Toolbar)findViewById(R.id.profile_action_toolbar);
        setSupportActionBar(toolbar);
        setTitle("Edit Profile");
        ActionBar actionBar= getSupportActionBar();
        actionBar.setDisplayHomeAsUpEnabled(true);
    }
}

This is how I started activity 2 from activity 1:

Intent i = new Intent(MainActivity.this,SecondActivity.class);
                    startActivity(i);

It is not going back when I click this button

Why it is not going back?

回答1:

Add the following to your activity.You have to handle the click event of the back button.

@Override
 public boolean onOptionsItemSelected(MenuItem item) {
      switch (item.getItemId()){
         case android.R.id.home:
              onBackPressed();
              return true;
       }
   return super.onOptionsItemSelected(item);
 }

回答2:

Here you have 2 options:

a) provide a parentActivityName to your SecondActivity tag in AndroidManifest.xml like this:

 <activity
    ...
    android:name=".SecondActivity"
    android:parentActivityName=".MainActivity" >

b) override onOptionsItemSelected in SecondActivity like this:

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    switch (item.getItemId()) {
    // Respond to the action bar's Up/Home button
    case android.R.id.home:
        onBackPressed();
        return true;
    }
    return super.onOptionsItemSelected(item);
}

I would suggest reading this guide for more information.

回答3:

I would suggest not to handle "android.R.id.home" in onOptionsItemSelected as it is brittle. Rather you should override onSupportNavigateUp method.

@Override
 public boolean onOptionsItemSelected(MenuItem item) {
      switch (item.getItemId()){
         case android.R.id.home:
              onBackPressed();
              return true;
       }
   return super.onOptionsItemSelected(item);
 }

Note: If you are using onOptionsItemSelected , then you should return false as default otherwise onSupportNavigateUp method is not called.

回答4:

Here is your code

 public class EditProfileActivity extends AppCompatActivity {

        @Override
        protected void onCreate(Bundle savedInstanceState) {

            super.onCreate(savedInstanceState);
            setContentView(R.layout.edit_profile);
            Toolbar toolbar = (Toolbar)findViewById(R.id.profile_action_toolbar);
            setSupportActionBar(toolbar);
            setTitle("Edit Profile");
            ActionBar actionBar= getSupportActionBar();
            actionBar.setDisplayHomeAsUpEnabled(true);
        }

        @Override
        public boolean onOptionsItemSelected(MenuItem item) {
            int id = item.getItemId();
            if (item.getItemId() == android.R.id.home) {
                   finish();
            }

            return super.onOptionsItemSelected(item);
        }
    }     

回答5:

First of all, always see Android Guidelines http://developer.android.com/intl/pt-br/design/patterns/navigation.html to prevent Google blocks Android apps.

Try to add this code in your Activity

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem menuItem) {
    switch (menuItem.getItemId()) {
        case android.R.id.home:
            onBackPressed();
            break;
    }

    return super.onOptionsItemSelected(menuItem);
}

@Override
public void onBackPressed() {
    super.onBackPressed();
}

回答6:

You have to override onOptionsItemSelected and check the item's id, if it is equals with home button's id, just call onBackPressed method.

@Override
        public boolean onOptionsItemSelected(MenuItem item) {
            if (item.getItemId() == android.R.id.home) {
                onBackPressed();
            }
            return super.onOptionsItemSelected(item);
        }

回答7:

You have to define what should happen when you click on that button, this can be done in your second activity's onOptionsItemSelected method. Notice the android.R.id.home constant which refers to the activity's back button that you want to use.

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    switch (item.getItemId()) {

    case android.R.id.home:

        finish(); //close the activty
        return true;
    }
    return super.onOptionsItemSelected(item);
}