Android——正确的Fragment写法

Fragment之前用的都是replace来替换，而且切换后台重新进入会直接导致重叠问题，这是因为没有保存fragment状态。

1。用newinstance来创建对应的fragment

public static BaseFragment newInstance(String name) {
BaseFragment fragment = new BaseFragment();
Bundle args = new Bundle();
args.putString("name", name);
fragment.setArguments(args);
return fragment;
}

2。oncreate根据保存fragment状态来判断展示fragment的呈现

@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (savedInstanceState != null) {
boolean isSupportHidden = savedInstanceState.getBoolean(STATE_SAVE_IS_HIDDEN);

FragmentTransaction ft = getFragmentManager().beginTransaction();
if (isSupportHidden) {
ft.hide(this);
} else {
ft.show(this);
}
ft.commit();
}
}

3。onsaveInstance用来保存fragment状态

@Override
public void onSaveInstanceState(Bundle outState) {
outState.putBoolean(STATE_SAVE_IS_HIDDEN, isHidden());
}

4。onactivitycreated中获取参数

@Override
public void onActivityCreated(@Nullable Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
String name = getArguments().getString("name");

//fragmentText.setText(name);

}

附完整代码：

package com.example.pelon.fragment;

import android.content.Context;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentTransaction;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import com.example.pelon.myteacher.R;

import butterknife.BindView;
import butterknife.ButterKnife;
import butterknife.Unbinder;

/**
* Created by PeLon on 2017/10/31.
*/

public class BaseFragment extends Fragment {
private static final String STATE_SAVE_IS_HIDDEN = "STATE_SAVE_IS_HIDDEN";
@BindView(R.id.fragment_text)
TextView fragmentText;
Unbinder unbinder;

public static BaseFragment newInstance(String name) {
BaseFragment fragment = new BaseFragment();
Bundle args = new Bundle();
args.putString("name", name);
fragment.setArguments(args);
return fragment;
}

@Override
public void onAttach(Context context) {
super.onAttach(context);
}

@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragmentlayout, null);
unbinder = ButterKnife.bind(this, view);
return view;

}

@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (savedInstanceState != null) {
boolean isSupportHidden = savedInstanceState.getBoolean(STATE_SAVE_IS_HIDDEN);

FragmentTransaction ft = getFragmentManager().beginTransaction();
if (isSupportHidden) {
ft.hide(this);
} else {
ft.show(this);
}
ft.commit();
}
}

@Override
public void onSaveInstanceState(Bundle outState) {
outState.putBoolean(STATE_SAVE_IS_HIDDEN, isHidden());
}

@Override
public void onActivityCreated(@Nullable Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
String name = getArguments().getString("name");

fragmentText.setText(name);

}

@Override
public void onDestroyView() {
super.onDestroyView();
unbinder.unbind();
}
}