简介：
Activity经常需要向Fragment进行数据传递,推荐使用fragment.newInstance的方式进行数据传递，以保证界面切换的时候数据不会丢失。
参考阅读：Android开发-Fragment和Activity传值相关(Fragment传值给Activity)
步骤一：MainActivity.java文件
package com.huwan.activity2fragmentvaluedemo2;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
public class MainActivity extends AppCompatActivity {
// 1.定义了几个字符串
private String aaaa = "字母a值";
private String bbbb = "字母b值";
private String cccc = "字母c值";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// 4.点击进行fragment切换
Button btn1;
Button btn2;
Button btn3;
btn1 = findViewById(R.id.btn1);
btn1.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
getSupportFragmentManager().beginTransaction().replace(R.id.content_frame, Fragment1.newInstance(aaaa, bbbb)).commit();
}
});
btn2 = findViewById(R.id.btn2);
btn2.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
getSupportFragmentManager().beginTransaction().replace(R.id.content_frame, Fragment1.newInstance(bbbb, cccc)).commit();
}
});
btn3 = findViewById(R.id.btn3);
btn3.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
getSupportFragmentManager().beginTransaction().replace(R.id.content_frame, Fragment1.newInstance(aaaa, cccc)).commit();
}
});
// 2.activity的数据可能是传递或者获取的，所以一定要进行判断
if (savedInstanceState != null) {
aaaa = savedInstanceState.getString("字母a值");
bbbb = savedInstanceState.getString("字母b值");
cccc = savedInstanceState.getString("字母c值");
}
}
// 3.防止数据丢失，一定要进行保存
@Override
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putString("字母a值", aaaa);
outState.putString("字母b值", bbbb);
outState.putString("字母c值", cccc);
}
}
步骤二：Fragment1.java文件
package com.huwan.activity2fragmentvaluedemo2;
import android.app.Activity;
import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.TextView;
public class Fragment1 extends Fragment {
//5.获取传递过来的值，并保存在bundle中
String zhi1;
String zhi2;
public static Fragment1 newInstance(String zhi1,String zhi2) {
Fragment1 newFragment = new Fragment1();
Bundle bundle = new Bundle();
bundle.putString("zhi1", zhi1);
bundle.putString("zhi2", zhi2);
newFragment.setArguments(bundle);
return newFragment;
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment1, container, false);
//6.将保存的值取出，进行展示
Bundle args = getArguments();
if (args != null){
zhi1 = args.getString("zhi1");
zhi2 = args.getString("zhi2");
TextView text1 = view.findViewById(R.id.text1);
text1.setText(zhi1);
TextView text2 = view.findViewById(R.id.text2);
text2.setText(zhi2);
}
return view;
}
}
步骤三：其它相关文件
activity_main.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<Button
android:id="@+id/btn1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textColor="@color/colorAccent"
android:textSize="20dp"
android:text="切换一" />
<Button
android:id="@+id/btn2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textColor="@color/colorAccent"
android:textSize="20dp"
android:text="切换二" />
<Button
android:id="@+id/btn3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textColor="@color/colorAccent"
android:textSize="20dp"
android:text="切换三" />
<FrameLayout
android:id="@+id/content_frame"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#ff0000"
android:fitsSystemWindows="true" />
</LinearLayout>
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fragment1.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:background="@color/colorAccent">
<TextView
android:id="@+id/text1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="20dp"
android:text="值一" />
<TextView
android:id="@+id/text2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="20dp"
android:text="值二"/>
</LinearLayout>
Demo样例下载：
http://www.huwan.xin/Source/AppPackage/ZIP/Android/ Activity2FragmentValueDemo2.rar
更多内容请访问：www.huwan.xin
