小编Dev*_*e01的帖子

我不知道什么是错的,每当我在模拟器上启动我的应用程序并切换到横向模式时,它就会崩溃.但它在纵向模式下工作正常.请问我能做些什么来解决这个问题.提前致谢!这是我的代码......

MainActivity.class

import android.app.FragmentTransaction;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;

import com.actgeek.android.myapplication.R;

public class MainActivity extends AppCompatActivity{

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

        MAFragment mfrag = new MAFragment();
        FragmentTransaction FT = getFragmentManager().beginTransaction();
        FT.replace(R.id.fragment, mfrag);
        FT.commit();

        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                        .setAction("Action", null).show();
            }
        });
    }

    @Override …