Fragment 替换

private void initViews() {
    fragment = findViewById(R.id.fragment);
    group = findViewById(R.id.group);

    final FragmentManager supportFragmentManager = getSupportFragmentManager();

    group.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
        @Override
        public void onCheckedChanged(RadioGroup group, int checkedId) {
            switch(checkedId){
                case R.id.but_01:
                    supportFragmentManager.beginTransaction().replace(R.id.fragment,new ZiXun()).commit();
                    break;
                case R.id.but_02:
                    supportFragmentManager.beginTransaction().replace(R.id.fragment,new BoKe()).commit();
                    break;
                case R.id.but_03:
                    supportFragmentManager.beginTransaction().replace(R.id.fragment,new KaiYuan()).commit();
                    break;
                case R.id.but_04:
                    supportFragmentManager.beginTransaction().replace(R.id.fragment,new QiTa()).commit();
                    break;
            }
        }
    });