android fragment manage 管理fragment demo

package com.jcdh.jcli.myapplication; import android.app.FragmentManager; import android.app.FragmentTransaction; import android.app.Activity; import android.os.Bundle; import android.view.View; import android.widget.Toast; public class MainActivity extends Activity { private FirstFragment fristFragment; private SecondFragment secondFragment; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); } public void moveToFragment(View view) { // 开启Fragment事务 FragmentManager fm = getFragmentManager(); FragmentTransaction transaction = fm.beginTransaction(); switch (view.getId()) { case R.id.first_btn: if (fristFragment == null) { fristFragment = new FirstFragment(); transaction.replace(R.id.first_fragment, fristFragment); } else { Toast.makeText(MainActivity.this, "已经添加过了fristFragment，不能重复添加", Toast.LENGTH_SHORT).show(); return; } break; case R.id.second_btn: if (secondFragment == null) { secondFragment = new SecondFragment(); transaction.replace(R.id.first_fragment, secondFragment); } else { Toast.makeText(MainActivity.this, "已经添加过了fristFragment，不能重复添加", Toast.LENGTH_SHORT).show(); return; } break; } transaction.addToBackStack(null); transaction.commit(); } public void removeFragment(View v) { if (getFragmentManager().getBackStackEntryCount() == 0) { Toast.makeText(MainActivity.this, "没有 Fragment 可以被 删除， ", Toast.LENGTH_SHORT).show(); return; } FragmentTransaction transaction = getFragmentManager().beginTransaction(); switch (v.getId()) { case R.id.button: if (null != fristFragment) { transaction.remove(fristFragment); fristFragment = null; Toast.makeText(MainActivity.this, "删除fristFragment， ", Toast.LENGTH_SHORT).show(); } else { Toast.makeText(MainActivity.this, "没有fristFragment可以被删除 ", Toast.LENGTH_SHORT).show(); } break; case R.id.button2: if (null != secondFragment) { transaction.remove(secondFragment); secondFragment = null; Toast.makeText(MainActivity.this, "删除secondFragment， ", Toast.LENGTH_SHORT).show(); } else { Toast.makeText(MainActivity.this, "没有删除secondFragment可以被删除 ", Toast.LENGTH_SHORT).show(); } break; } transaction.commit();// 一定要提交才能生效 } }