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。

数据传递与数据回传

 

 

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();
    }
}

 

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