Activity值回传

1.值回传：将A界面里的数据传递到B界面里，在B界面里需要将A界面里的数据处理之后再返回到A界面。

2.创建MainActivity类对应的布局文件activity_main.xml

<RelativeLayout 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:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.example.intent_result.MainActivity" >

<EditText
android:id="@+id/editText1"
android:layout_width="70dp"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:ems="10" >
</EditText>

<TextView
android:id="@+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="@+id/editText1"
android:layout_alignBottom="@+id/editText1"
android:layout_toRightOf="@+id/editText1"
android:textSize="30sp"
android:text=" + "
/>

<EditText
android:id="@+id/editText2"
android:layout_width="70dp"
android:layout_height="wrap_content"
android:layout_alignBaseline="@+id/textView1"
android:layout_alignBottom="@+id/textView1"
android:layout_toRightOf="@+id/textView1"
android:ems="10" >

<requestFocus />
</EditText>

<TextView
android:id="@+id/textView2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="@+id/editText2"
android:layout_alignBottom="@+id/editText2"
android:layout_toRightOf="@+id/editText2"
android:textSize="30sp"
android:text=" = "  />

<EditText
android:id="@+id/editText3"
android:layout_width="70dp"
android:layout_height="wrap_content"
android:layout_alignTop="@+id/textView2"
android:layout_toRightOf="@+id/textView2"
android:ems="10" />

<Button
android:id="@+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/editText2"
android:layout_marginTop="48dp"
android:layout_toLeftOf="@+id/textView2"
android:text="提交" />

</RelativeLayout>

界面效果：



3.创建MainActivity类

(1) 通过findViewById()方法获取相应的控件

(2) 将数据通过intent传递到另一个界面

(3) startActivityForResult (intent,requestCode),requestCode表示请求码，就是当前类定义的一个数值，当前类为请求类。

(4) 我们要从另一个activity里面获取返回的值，需要实现onActivityResult这个方法，onActivityResult(int requestCode, int resultCode, Intent data)，requestcode表示请求码，resultcode 表示返回的结果码，data表示存放返回的数据。通过验证返回码和请求码，我们就可以获取另一个activity返回的数据了。

package com.example.intent_result;

import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;

public class MainActivity extends ActionBarActivity {
private Button button;
private EditText editText1,editText2,editText3;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
button = (Button) findViewById(R.id.button1);
editText1 = (EditText) findViewById(R.id.editText1);
editText2 = (EditText) findViewById(R.id.editText2);
editText3 = (EditText) findViewById(R.id.editText3);

button.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
String text1 = editText1.getText().toString().trim();
String text2 = editText2.getText().toString().trim();
Intent intent = new Intent(MainActivity.this,NextActivity.class);
intent.putExtra("message", text1 + "+" + text2 + "=" + "?");
startActivityForResult(intent, 1000);
}
});
}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if(requestCode ==1000 && resultCode==1001){
String result = data.getStringExtra("result");
editText3.setText(result);
}
};

}

4.创建NextActivity类对应的布局文件activity_next.xml

<RelativeLayout 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:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.example.intent_result.MainActivity" >

<TextView
android:id="@+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:layout_marginLeft="15dp"
android:layout_marginTop="33dp"
android:textSize="20sp"
android:text="" />

<EditText
android:id="@+id/editText1"
android:layout_width="100sp"
android:layout_height="wrap_content"
android:layout_alignBaseline="@+id/textView1"
android:layout_alignBottom="@+id/textView1"
android:layout_marginLeft="23dp"
android:layout_toRightOf="@+id/textView1"
android:ems="10" >
</EditText>

<Button
android:id="@+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="@+id/editText1"
android:layout_alignBottom="@+id/editText1"
android:layout_toRightOf="@+id/editText1"
android:text="计算结果" />

</RelativeLayout>

界面效果:



5.创建NextActivity类

(1) 将计算的结果填到输入框里面，点击提交就会返回到Mactivity_main.xml的textedit3里面

(2) 通过setResult(1001, intent);将值放到intent里面，传递到onActivityResult(int requestCode, int resultCode, Intent data) {

这个方法里的data里面。

(3) finish(); //结束activity的生命周期

package com.example.intent_result;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class NextActivity extends Activity {
private EditText editText;
private TextView textView;
private Button button;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_next);
editText = (EditText) this.findViewById(R.id.editText1);
textView = (TextView) this.findViewById(R.id.textView1);
button = (Button) this.findViewById(R.id.button1);

Intent intent = getIntent();
String message = intent.getStringExtra("message");
textView.setText(message);
button.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
String value = editText.getText().toString().trim();
Intent intent = new Intent();
intent.putExtra("result", value);
//设置回传的意图
setResult(1001, intent);
finish(); //结束activity的生命周期
}
});
}
}

5.AndroidManifest.xml注册NextActivity

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.intent_result"
android:versionCode="1"
android:versionName="1.0" >

<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="17" />

<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name=".MainActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />

<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:name=".NextActivity"></activity>
</application>

</manifest>