startActivity(intent)

startActivityForResult(intent,requestCode);
onActivityResult(int requestCode,int resultCode,Intent data)
setResult(resultCode,data);

package com.example.hello;
import android.app.Activity;
import android.content.Context;
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 FActivity extends Activity{
  private Button bt1;
  private Context mContext;
  private Button bt2;
  private TextView tv;
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.factivity);
    /*
     * 通过点击bt1实现页面之间的跳转
     * 1.startActivity来实现跳转
     * 1>初始换Intent
     */
    mContext = this;
    bt1 = (Button) findViewById(R.id.button1_first);
    bt2 = (Button) findViewById(R.id.button2_second);
    tv = (TextView) findViewById(R.id.textView1);
    //注册点击事件
    bt1.setOnClickListener(new OnClickListener() {
      @Override
      public void onClick(View v) {
        /**
         * 第一个参数，上下文对象this
         * 第二个参数，目标文件
         */
        Intent intent = new Intent(mContext, SActivity.class);
        startActivity(intent);
      }
    });
    /*
     * 通过startActivityForResult
     * 第二个参数是请求的一个标识
     */
    bt2.setOnClickListener(new OnClickListener() {
      @Override
      public void onClick(View v) {
        Intent intent = new Intent(mContext, SActivity.class);
        startActivityForResult(intent, 1);
      }
    });
  }
  /*
   * 通过startActivityForResult 跳转，接受返回数据的方法
   * requestCode:请求标识
   * resultCode:第二个页面返回的标识
   * data 第二个页面回传的数据
   */
  @Override
  protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    if (requestCode == 1 && resultCode == 2) {
      String content = data.getStringExtra("data");
      tv.setText(content);
    }
  }
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:orientation="vertical" >
  <Button
    android:id="@+id/button1_first"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:text="第一种启动方式" />
  <Button
    android:id="@+id/button2_second"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:text="第二种启动方式" />
  <TextView
    android:id="@+id/textView1"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:text="把第二个页面回传的数据显示出来" />
</LinearLayout>

package com.example.hello;
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;
public class SActivity extends Activity{
  private Button bt;
  private String content = "你好";
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.sactivity);
    /*
     * 第二个页面什么时候回传数据给第一个页面
     * 回传到第一个页面的，实际上是一个Intent对象
     */
    bt = (Button) findViewById(R.id.button1);
    bt.setOnClickListener(new OnClickListener() {
      @Override
      public void onClick(View v) {
        Intent data = new Intent();
        data.putExtra("data", content);
        setResult(2, data);
        //结束当前页面
        finish();
      }
    });
  }
}

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

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
  package="com.example.hello"
  android:versionCode="1"
  android:versionName="1.0" >
  <uses-sdk
    android:minSdkVersion="8"
    android:targetSdkVersion="21" />
  <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" >
    </activity>
    <activity
      android:name=".FActivity"
      android:label="@string/app_name" >
      <!-- 首启动项 -->
      <intent-filter>
        <action android:name="android.intent.action.MAIN" />
        <category android:name="android.intent.category.LAUNCHER" />
      </intent-filter>
    </activity>
    <activity
      android:name=".SActivity"
      android:label="@string/app_name" >
    </activity>
  </application>
</manifest>

Uri uri = Uri.parse("http://www.baidu.com");
Intent intent = new Intent(Intent.ACTION_VIEW, uri);
startActivity(intent);