数据传递与数据回传
1.按照图(1)布局编写第一个Activity，点击按钮后跳转到第二个Activity并将选择的结果数据一起传递过去。
2.按照图(2)编写第二个Activity，显示第一个Activity传递的数据内容，点击按钮后跳转到第三个Activity。
3.按照图(3)编写第三个Activity，用ListView实现列表展示信息，点击列表某行信息后跳转回第二个Activity，并将列表中数据回传给第二个Activity，并且在第二个Activity中对信息进行展示。
根据上图，先写出xml布局：
第一个
1 <?xml version="1.0" encoding="utf-8"?> 2 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 3 android:layout_width="match_parent" 4 android:layout_height="match_parent" 5 android:orientation="horizontal"> 6 <TextView 7 android:layout_width="wrap_content" 8 android:layout_height="wrap_content" 9 android:text="水果："/> 10 11 <LinearLayout 12 android:layout_width="wrap_content" 13 android:layout_height="wrap_content" 14 android:orientation="vertical"> 15 <CheckBox 16 android:id="@+id/apple" 17 android:layout_width="wrap_content" 18 android:layout_height="wrap_content" 19 android:text="苹果"/> 20 <CheckBox 21 android:id="@+id/orange" 22 android:layout_width="wrap_content" 23 android:layout_height="wrap_content" 24 android:text="橙子"/> 25 <CheckBox 26 android:id="@+id/watermelon" 27 android:layout_width="wrap_content" 28 android:layout_height="wrap_content" 29 android:text="西瓜"/> 30 <CheckBox 31 android:id="@+id/grape" 32 android:layout_width="wrap_content" 33 android:layout_height="wrap_content" 34 android:text="葡萄"/> 35 36 <Button 37 android:id="@+id/tijiao" 38 android:layout_width="wrap_content" 39 android:layout_height="wrap_content" 40 android:text="提交" /> 41 </LinearLayout> 42 43 </LinearLayout>
第二个
1 <?xml version="1.0" encoding="utf-8"?> 2 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 3 android:layout_width="match_parent" 4 android:layout_height="match_parent" 5 android:orientation="vertical"> 6 7 <LinearLayout 8 android:layout_width="wrap_content" 9 android:layout_height="wrap_content" 10 android:orientation="vertical"> 11 12 <TextView 13 android:layout_width="wrap_content" 14 android:layout_height="wrap_content" 15 android:text="选择了：" /> 16 17 <TextView 18 android:id="@+id/fruit" 19 android:layout_width="wrap_content" 20 android:layout_height="wrap_content" /> 21 22 <TextView 23 android:layout_width="wrap_content" 24 android:layout_height="wrap_content" 25 android:text="商家是：" /> 26 27 <TextView 28 android:id="@+id/shop" 29 android:layout_width="wrap_content" 30 android:layout_height="wrap_content" /> 31 32 </LinearLayout>> 33 34 <Button 35 android:id="@+id/c_shop" 36 android:layout_width="wrap_content" 37 android:layout_height="wrap_content" 38 android:text="选择商家" /> 39 40 </LinearLayout>
第三个
1 <?xml version="1.0" encoding="utf-8"?> 2 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 3 xmlns:app="http://schemas.android.com/apk/res-auto" 4 android:orientation="horizontal" 5 android:layout_width="wrap_content" 6 android:layout_height="wrap_content"> 7 <ListView 8 android:id="@+id/shows" 9 android:layout_width="wrap_content" 10 android:layout_height="wrap_content"/> 11 12 </LinearLayout>
需要三个activity，从MainActivity开始，对应图（1）
MainActivity重点是我们要发送页面的值给SecondActivity（图2）
我们单独写一个方法buy_fruit()
1 public void buy_fruit() { 2 Intent intent_1 = new Intent(this,SecondActivity.class); 3 intent_1.putExtra("buy_fruits",buy_fruits); 4 startActivity(intent_1); 5 6 }
还有我们用多选按钮来进行选择的过程，思路就是点击按钮，将选择的水果打包起来传出去
传递数据需要用到Intent提供的putExtra()方法
1 Intent intent = new Intent(this,Activity02.class); 2 intent.putExtra("extra_data","Hello Activity02"); 3 startActivity(intent);
1 Intent intent = getIntent(); 2 String data = intent.getStringExtra("extra_data");
那就好说了，写代码喽
1 Button tijiao = (Button) findViewById(R.id.tijiao); 2 tijiao.setOnClickListener(new View.OnClickListener() { 3 @Override 4 public void onClick(View view) { 5 String str="";//保存所有选中的值 6 if(apple.isChecked())//选中苹果 7 str+=apple.getText().toString()+""; 8 if(orange.isChecked())//选中橘子 9 str+=orange.getText().toString()+""; 10 if(watermelon.isChecked())//选中西瓜 11 str+=watermelon.getText().toString()+""; 12 if(grape.isChecked())//选中葡萄 13 str+=grape.getText().toString(); 14 buy_fruits = str; 15 if(buy_fruits.equals("")){ 16 Toast.makeText(MainActivity.this,"不可以空选",Toast.LENGTH_SHORT).show(); 17 }else { 18 Toast.makeText(MainActivity.this,str,Toast.LENGTH_SHORT).show(); 19 buy_fruit(); 20 } 21 } 22 });
好了，我们第一个activity写完了,开始写SecondActivity
这个是最难写的，它要接收两个值，第一个的和第三个的数据回传的值，所以我们可以分成两部分来写，
先写接收MainActivity的值，并显示在图（2）上
1 Intent buy_fruits = getIntent(); 2 String fruits = buy_fruits.getStringExtra("buy_fruits"); 3 fruit = (TextView) findViewById(R.id.fruit); 4 fruit.setText(fruits);
然后写数据回传，这个过程是点击按钮跳转到thirdActivity上，thirdActivity将数据传回来
这个过程的代码是这样的
1 Intent intent = new Intent(this,Active02.class); 2 startActivityForResult(intent,1); //这里的1就是rquestCode
//进行跳转，数据回传的开始
1 Intent intent = new Intent(); 2 intent.putExtra("extra_data","Hello Activity01"); 3 setResult(1,intent); //这里的1是resultCode
//另一个activity回传数据
1 protected void onActivityResult(int requestcode,int resultcode,Intent data){ 2 super.onActivityResult(requestcode,resultcode,c); 3 if (requestcode == 1 && resultcode == 1){ 4 String string = data.getStringExtra("extra_data"); 5 } 6 }
//重写onActivityResult()方法用来接收数据
然后我们就可以根据上面的代码来写我们的代码了
1 public void c_shops() { 2 Intent intent = new Intent(this,thirdActivity.class); 3 startActivityForResult(intent,1); 4 } 5 protected void onActivityResult(int requestcode,int resultcode,Intent c){ 6 super.onActivityResult(requestcode,resultcode,c); 7 if (requestcode == 1 && resultcode == 1){ 8 String shops = c.getStringExtra("shop"); 9 shop = (TextView) findViewById(R.id.shop); 10 shop.setText(shops); 11 } 12 }
1 public void c_shop(String oshop){ 2 Intent intent = new Intent(); 3 intent.putExtra("shop",oshop); 4 setResult(1,intent); 5 finish(); 6 }
secondActivity主要内容也写好了
thirdActiyity主要内容也写好了
附上三个actiyity的全部代码
package com.example.app; import androidx.appcompat.app.AppCompatActivity; import android.support.v4.app.*; import androidx.appcompat.app.AlertDialog; import android.text.TextUtils; import android.os.Bundle; import android.view.View; import android.widget.*; import android.content.Intent; public class MainActivity extends AppCompatActivity { private CheckBox apple; private CheckBox orange; private CheckBox watermelon; private CheckBox grape; private Button tijiao; String buy_fruits; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.homework_seven_1); apple = (CheckBox) findViewById(R.id.apple); orange = (CheckBox) findViewById(R.id.orange); watermelon = (CheckBox) findViewById(R.id.watermelon); grape = (CheckBox) findViewById(R.id.grape); Button tijiao = (Button) findViewById(R.id.tijiao); tijiao.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { String str="";//保存所有选中的值 if(apple.isChecked())//选中苹果 str+=apple.getText().toString()+""; if(orange.isChecked())//选中橘子 str+=orange.getText().toString()+""; if(watermelon.isChecked())//选中西瓜 str+=watermelon.getText().toString()+""; if(grape.isChecked())//选中葡萄 str+=grape.getText().toString(); buy_fruits = str; if(buy_fruits.equals("")){ Toast.makeText(MainActivity.this,"不可以空选",Toast.LENGTH_SHORT).show(); }else { Toast.makeText(MainActivity.this,str,Toast.LENGTH_SHORT).show(); buy_fruit(); } } }); } public void buy_fruit() { Intent intent_1 = new Intent(this,SecondActivity.class); intent_1.putExtra("buy_fruits",buy_fruits); startActivity(intent_1); } }
package com.example.app; import androidx.appcompat.app.AppCompatActivity; import androidx.appcompat.app.AlertDialog; import android.util.Log; import android.text.TextUtils; import android.os.Bundle; import android.view.View; import android.widget.Button; import android.widget.EditText; import android.content.Intent; import android.widget.TextView; public class SecondActivity extends AppCompatActivity { private TextView fruit; private Button c_shop; private TextView shop; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.homework_seven_2); Intent buy_fruits = getIntent(); String fruits = buy_fruits.getStringExtra("buy_fruits"); fruit = (TextView) findViewById(R.id.fruit); fruit.setText(fruits); shop = (TextView) findViewById(R.id.shop); c_shop = (Button) findViewById(R.id.c_shop); c_shop.setOnClickListener(new View.OnClickListener(){ public void onClick(View view) { c_shops(); } }); } public void c_shops() { Intent intent = new Intent(this,thirdActivity.class); startActivityForResult(intent,1); } protected void onActivityResult(int requestcode,int resultcode,Intent c){ super.onActivityResult(requestcode,resultcode,c); if (requestcode == 1 && resultcode == 1){ String shops = c.getStringExtra("shop"); shop = (TextView) findViewById(R.id.shop); shop.setText(shops); } } }
package com.example.app; import android.os.*; import android.view.View; import android.widget.*; import android.content.Intent; import androidx.appcompat.app.AppCompatActivity; public class thirdActivity extends AppCompatActivity { private static String[] shops = new String[]{ "甘福园旗舰店","福瑞达水果汇","沁园春百果园","西域美食品" }; private ListView lv; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.homework_seven_3); lv = (ListView) findViewById(R.id.shows); ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,shops);//新建并配置ArrayAapeter lv.setAdapter(adapter); lv.setOnItemClickListener(new AdapterView.OnItemClickListener(){ //设置监听 @Override public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) { switch (i) { case 0: c_shop("甘福园旗舰店"); break; case 1: c_shop("福瑞达水果汇"); break; case 2: c_shop("沁园春百果园"); break; case 3: c_shop("西域美食品"); break; } } }); } public void c_shop(String oshop){ Intent intent = new Intent(); intent.putExtra("shop",oshop); setResult(1,intent); finish(); } }
