安卓fragment transaction add方法报错

这个问题百度了很多能用的很少！

原来看的B站的视频教程比较老了参数不匹配！我记一下安卓studio3.1的方法

切换fragment 前都先要 FragmentManager manager=getSupportFragmentManager（）  //这个是 android.support.v4.app.FragmentManager;

然后FragmentTransaction transaction=manager.beginTransaction();  之后执行  transaction.replace(fragment 的id); 最后  transaction.commit();

感觉一般主窗口载入窗口你会Add一个fragment  之后点击切换的时候 程序就会崩溃！！！！  你要在载入你fragment  前面加入 transaction=manager.beginTransaction();不管你载入那个fragment  都加这一句

代码如下写的很low 凑合看

主窗口代码

package com.stdu.myllogin;

import android.support.v4.app.FragmentManager;

import android.support.v4.app.FragmentTransaction;

import android.support.v7.app.AppCompatActivity;

import android.os.Bundle;

import android.view.View;

import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

private TextView zhanghaodenglu;

private TextView dongtaimimadenglu;

private FragmentManager manager;

private FragmentTransaction transaction;

private  YanZhengMaFragment yanZhengMaFragment;

private   LoginFragment loginFragment;

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

       loginFragment=new LoginFragment();

        manager= getSupportFragmentManager();

      transaction=manager.beginTransaction();

      transaction.replace(R.id.login_frea,loginFragment);

      transaction.commit();

      zhanghaodenglu=findViewById(R.id.zhanghao_login);

      dongtaimimadenglu=findViewById(R.id.mima_login);

      zhanghaodenglu.setOnClickListener(listener);

      dongtaimimadenglu.setOnClickListener(listener);

        yanZhengMaFragment=new YanZhengMaFragment();

        loginFragment=new LoginFragment();

    }

    private View.OnClickListener listener=new View.OnClickListener() {

        @Override

        public void onClick(View view) {

            switch (view.getId())

            { case R.id.mima_login:

                hideFragment(transaction);

                //transaction.remove(loginFragment);

                transaction=manager.beginTransaction();//这里一定要再写一遍 否则会出错

                transaction.replace(R.id.login_frea,yanZhengMaFragment);

                transaction.commit();

              //  Toast.makeText(MainActivity.this,"验证码登陆测试",Toast.LENGTH_SHORT).show();

                break;

                case  R.id.zhanghao_login:

                    hideFragment(transaction);

                    transaction=manager.beginTransaction();//这里一定要再写一遍 否则会出错

                    transaction.replace(R.id.login_frea,loginFragment);

                    transaction.commit();

                    //Toast.makeText(MainActivity.this,"账号登陆测试",Toast.LENGTH_SHORT).show();

                    break;

            }

        }

    };

    private void hideFragment(FragmentTransaction transaction) {

        if (loginFragment != null) {

            transaction.remove(loginFragment);

        }

        if (yanZhengMaFragment != null) {

            transaction.remove(yanZhengMaFragment);

        }

    }

}

　　布局界面不写了看看我的哈皮运行截图吧