Fragment的重複載入問題。之前在一些小專案中經常用到Fragment，一般都使用fragmentTransaction.replace(R.id.content,user_Fa)去動態載入佈局。因為之前專案小，user_fa該fragment資料量比較少，對整體專案並無影響所以就沒去管，直到前天，遇到載入的fragment資料量比較大。切換fragment時出現卡頓現象，分析其原因竟然是每次呼叫replace都會去載入一次fragment,而此時的fragment又好大，所以就出現卡頓現象，載入一次fragment說白了就是每次replace都會呼叫onCreateView方法，要是不信你可以打Log測試一下，那碰到這卡頓怎麼辦勒，還記得fragment給我們提供了另外的方法嗎？add和show方法可以幫我解決這個問題，看程式碼吧 

import android.app.FragmentManager;
import android.app.FragmentTransaction;
import android.os.Bundle;
import android.view.View;
import android.widget.FrameLayout;
import android.widget.ImageView;
import android.widget.RadioButton;
import android.widget.TextView;
import Fragment.SheZhiFragment;
import 
 
Fragment.ShiPinFragment;
import Fragment.ShiTiFragment;
import Fragment.ShouYeFragment;
import base.BaseActivity;
import butterknife.BindView;
import butterknife.ButterKnife;
import cn.bmob.v3.update.BmobUpdateAgent;
public class MainActivity extends BaseActivity implements View.OnClickListener {


    @BindView
 
(R.id.fanhui_btn)
    ImageView fanhuiBtn;
@BindView(R.id.text_title)
    TextView textTitle;
@BindView(R.id.edit)
    ImageView edit;
@BindView(R.id.shiti)
    RadioButton shiti;
@BindView(R.id.shipin)
    RadioButton shipin;
@BindView(R.id.shezhi)
    RadioButton shezhi;
@BindView(R.id.fragmentcontent)
    FrameLayout fragmentcontent;
@BindView(R.id.shouye)
    RadioButton shouye;
    private ShiTiFragment shitifragment = null;
    private ShiPinFragment shipinfragment = null;
    private SheZhiFragment shezhifragment = null;
    private ShouYeFragment shouyefragment = null;
@Override
protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
BmobUpdateAgent.update(this);
setContentView(R.layout.activity_main);
ButterKnife.bind(this);
setDefaultFragment();
shiti.setOnClickListener(this);
shipin.setOnClickListener(this);
shezhi.setOnClickListener(this);
shouye.setOnClickListener(this);
fanhuiBtn.setOnClickListener(this);
}

    @Override
public void onClick(View v) {
        FragmentManager fm = getFragmentManager();
FragmentTransaction transaction = fm.beginTransaction();
        switch (v.getId()) {

            case R.id.shouye:
                textTitle.setText("首頁");
                if (shouyefragment == null) {
                    shouyefragment = new ShouYeFragment();
}
                //如果tab2不為空，把tab2隱藏就是、
if (shitifragment != null) {
                    transaction.hide(shitifragment);
}
                if (shipinfragment != null) {
                    transaction.hide(shipinfragment);
}
                if (shezhifragment != null) {
                    transaction.hide(shezhifragment);
}
                if (!shouyefragment.isAdded()) {

                    transaction.add(R.id.fragmentcontent, shouyefragment);
} else {
                    transaction.show(shouyefragment);
}
                break;
            case R.id.shiti:
                textTitle.setText("C語言試題");
                if (shitifragment == null) {
                    shitifragment = new ShiTiFragment();
}
                //如果tab2不為空，把tab2隱藏就是、
if (shouyefragment != null) {
                    transaction.hide(shouyefragment);
}
                if (shipinfragment != null) {
                    transaction.hide(shipinfragment);
}
                if (shezhifragment != null) {
                    transaction.hide(shezhifragment);
}
                if (!shitifragment.isAdded()) {

                    transaction.add(R.id.fragmentcontent, shitifragment);
} else {
                    transaction.show(shitifragment);
}
                break;
            case R.id.shipin:
                textTitle.setText("C語言視訊");
                if (shipinfragment == null) {
                    shipinfragment = new ShiPinFragment();
}
                //如果tab2不為空，把tab2隱藏就是、
if (shouyefragment != null) {
                    transaction.hide(shouyefragment);
}
                if (shitifragment != null) {
                    transaction.hide(shitifragment);
}
                if (shezhifragment != null) {
                    transaction.hide(shezhifragment);
}
                if (!shipinfragment.isAdded()) {

                    transaction.add(R.id.fragmentcontent, shipinfragment);
} else {
                    transaction.show(shipinfragment);
}
                break;
            case R.id.shezhi:
                textTitle.setText("設定");
                if (shezhifragment == null) {
                    shezhifragment = new SheZhiFragment();
}
                //如果tab2不為空，把tab2隱藏就是、
if (shouyefragment != null) {
                    transaction.hide(shouyefragment);
}
                if (shitifragment != null) {
                    transaction.hide(shitifragment);
}
                if (shipinfragment != null) {
                    transaction.hide(shipinfragment);
}
                if (!shezhifragment.isAdded()) {

                    transaction.add(R.id.fragmentcontent, shezhifragment);
} else {
                    transaction.show(shezhifragment);
}
                break;
            case R.id.fanhui_btn:
                finish();
                break;
}
        transaction.commit();
}

    private void setDefaultFragment() {
        FragmentManager fm = getFragmentManager();
FragmentTransaction transaction = fm.beginTransaction();
        if (shouyefragment == null) {
            shouyefragment = new ShouYeFragment();
}
        //如果tab2不為空，把tab2隱藏就是、
if (shipinfragment != null) {
            transaction.hide(shipinfragment);
}
        if (shitifragment != null) {
            transaction.hide(shitifragment);
}
        if (shezhifragment != null) {
            transaction.hide(shezhifragment);
}
        if (!shouyefragment.isAdded()) {

            transaction.add(R.id.fragmentcontent, shouyefragment);
} else {
            transaction.show(shouyefragment);
}

        transaction.commit();
}
}