Android 初识Intent

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
<Button 
    android:id="@+id/button1"
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:text="@string/button1"
    />
</LinearLayout>

package com.Neddy;

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.Toast;

public class MainActivity extends Activity
{
    private Button button=null;
    private final static int REQUEST_CODE=1;
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        button=(Button)findViewById(R.id.button1);
        button.setOnClickListener(listener);
    }
    
    private OnClickListener listener=new OnClickListener()
    {
        public void onClick(View v)
        {
//            Intent intent=new Intent();
//            intent.setAction(Intent.ACTION_SENDTO);
//            intent.setData(Uri.parse("smsto:5554"));
//            intent.putExtra("sms_body", "Welcome to ...");
//            startActivity(intent);
            Intent intent=new Intent();
            intent.setClass(MainActivity.this,SecondActivity.class);
            intent.putExtra("str", "HI,hello world!");
//            startActivity(intent);
            startActivityForResult(intent, REQUEST_CODE);
        }
    };
    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data)
    {
        if(requestCode==REQUEST_CODE)
        {
            if(resultCode==SecondActivity.RESULT_CODE)
            {
                Bundle bundle=data.getExtras();
                String str=bundle.getString("back");
                Toast.makeText(MainActivity.this,str,Toast.LENGTH_LONG).show();
            }
            
        }
    }
    
}

package com.Neddy;

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.TextView;

public class SecondActivity extends Activity
{
    private TextView second=null;
    private Button button2=null;
    final static int RESULT_CODE=1;
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.second);
        Intent intent=getIntent();
        Bundle bundle=intent.getExtras();
        String str=bundle.getString("str");
        second=(TextView)findViewById(R.id.second);
        second.setText(str);
        
        button2=(Button)findViewById(R.id.button2);
        
        button2.setOnClickListener(listener);
        
    }
    
    private OnClickListener listener=new OnClickListener()
    {
        public void onClick(View v)
        {
            Intent intent=new Intent();
            intent.putExtra("back", "Back Data");
            setResult(RESULT_CODE,intent);
            finish();
        }
    };

}

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

    <application android:icon="@drawable/icon" android:label="@string/app_name">
        <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=".SecondActivity"
                  android:label="Second">
        </activity>

    </application>
    <uses-permission android:name="android.permission.SEND_SMS"/>
</manifest>