【Android开发】启动另一个Activity_android启动activity方法

Intent intent = new Intent(this, DisplayMessageActivity.class);

• Context作为其第一个参数（此处用this，因为Activity类是Context的子类）
• App组件的类，系统将传递Intent到该类

/* Called when the user clicks the Send Button */
    public void sendMessage(View view){
    	// Do something in response to button
    	Intent intent = new Intent(this, DisplayMessageActivity.class);
    	EditText editText = (EditText)findViewById(R.id.edit_message);
    	String message = editText.getText().toString();
    	intent.putExtra(EXTRA_MESSAGE, message);
    }

public class MainActivity extends Activity {
 
    public static final String EXTRA_MESSAGE = "com.example.myfirstapp.MESSAGE";
    ...
}

/* Called when the user clicks the Send Button */
    public void sendMessage(View view){
    	// Do something in response to button
    	Intent intent = new Intent(this, DisplayMessageActivity.class);
    	EditText editText = (EditText)findViewById(R.id.edit_message);
    	String message = editText.getText().toString();
    	intent.putExtra(EXTRA_MESSAGE, message);
    	startActivity(intent);
    }

• Project：MyFirstApp
• Activity Name:DisplayMessageActivity
• LayoutName:activity_display_message
• Title:My Message
• Hierarchial Parent:com.example.myfirstapp.MainActivity
• Navigation Type:None

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.MenuItem;
import android.support.v4.app.NavUtils;
import android.annotation.TargetApi;
import android.os.Build;
 
public class DisplayMessageActivity extends Activity {
 
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_display_message);
		// Show the Up button in the action bar.
		setupActionBar();
	}
 
	/**
	 * Set up the {@link android.app.ActionBar}, if the API is available.
	 */
	@TargetApi(Build.VERSION_CODES.HONEYCOMB)
	private void setupActionBar() {
		if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
			getActionBar().setDisplayHomeAsUpEnabled(true);
		}
	}
 
	@Override
	public boolean onCreateOptionsMenu(Menu menu) {
		// Inflate the menu; this adds items to the action bar if it is present.
		getMenuInflater().inflate(R.menu.display_message, menu);
		return true;
	}
 
	@Override
	public boolean onOptionsItemSelected(MenuItem item) {
		switch (item.getItemId()) {
		case android.R.id.home:
			// This ID represents the Home or Up button. In the case of this
			// activity, the Up button is shown. Use NavUtils to allow users
			// to navigate up one level in the application structure. For
			// more details, see the Navigation pattern on Android Design:
			//
			//  http://developer.android.com/design/patterns/navigation.html#up-vs-back
			//
			NavUtils.navigateUpFromSameTask(this);
			return true;
		}
		return super.onOptionsItemSelected(item);
	}
 
}

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android=" http://schemas.android.com/apk/res/android"
    package="com.example.myfirstapp"
    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="com.example.myfirstapp.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="com.example.myfirstapp.DisplayMessageActivity"
            android:label="@string/title_activity_display_message"
            android:parentActivityName="com.example.myfirstapp.MainActivity" >
            <meta-data
                android:name="android.support.PARENT_ACTIVITY"
                android:value="com.example.myfirstapp.MainActivity" />
        </activity>
    </application>
 
</manifest>

protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		
		// Get the message from the intent
		Intent intent = getIntent();
		String message = intent.getStringExtra(MainActivity.EXTRA_MESSAGE);
		
		// Create the text view
		TextView textView = new TextView(this);
		textView.setTextSize(40);
		textView.setText(message);
		
//		setContentView(R.layout.activity_display_message);
		setContentView(textView);
		
		// Show the Up button in the action bar.
		setupActionBar();	
		
	}