fragment加载

package com.bawei.yuekaolianxi01;import android.os.Bundle;import android.support.v4.app.FragmentManager;import android.support.v7.app.AppCompatActivity;import android.view.View;public class MainActivity extends AppCompatActivity implements View.OnClickListener {    private FragmentManager manager;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        manager = getSupportFragmentManager();//获取Fragment管理者        manager.beginTransaction().replace(R.id.fram,new Fragment01()).commit();//默认加载第一个        findViewById(R.id.bt_wea).setOnClickListener(this);        findViewById(R.id.bt_sel).setOnClickListener(this);    }    @Override    public void onClick(View view) {        switch (view.getId()){            case R.id.bt_wea:                manager.beginTransaction().replace(R.id.fram,new Fragment01()).commit();                break;            case R.id.bt_sel:                manager.beginTransaction().replace(R.id.fram,new Fragment02()).commit();                break;        }    }}