小编Ani*_*ain的帖子

尝试了很多方法，但没有一个完美地工作。我想从导航视图中设置的片段中获取主要活动。我试过

@Override
public void onBackPressed() {
    startActivity(new Intent(this, MainActivity.class));
}

但它不会正常工作。我希望它就像当我处于零散的活动中时它返回到主活动，而再次单击返回时它退出（我已经这样做了），当按下返回时帮助我回到主活动

主活动.java

public class MainActivity extends AppCompatActivity {

private static final int PERMISSION_REQUEST_CODE = 1000 ;

private static final String TAG = "MainActivity";

private AdView mAdView;

ImageView imageView;


RecyclerView recyclerView;
RecyclerView.LayoutManager layoutManager;

List<Item> items;
CustomAdapter adapter;
private long backpressedtime;




@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
    super.onRequestPermissionsResult(requestCode, permissions, grantResults);
    switch (requestCode)
    {
        case PERMISSION_REQUEST_CODE:
        {
            if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED)
                Toast.makeText(this, "Permission …