Android初学第47天

13_Toolbar

代码

SingleFragmentActivity.java

package com.bignerdranch.android.criminalintent;import android.os.Bundle;import android.support.v4.app.Fragment;import android.support.v4.app.FragmentManager;import android.support.v7.app.AppCompatActivity;public abstract class SingleFragmentActivity extends AppCompatActivity {    protected abstract Fragment createFragment();    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_fragment);        FragmentManager fm = getSupportFragmentManager();        Fragment fragment = fm.findFragmentById(R.id.fragment_container);        if (fragment == null) {            fragment = createFragment();            fm.beginTransaction()                    .add(R.id.fragment_container, fragment)                    .commit();        }    }}