Android学习2——Activity之间跳转

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Activity是Android的四大控件之一，它是直接和用户打交道的界面，既然作为界面，那么界面和界面之间将会有一定的通讯，通讯则代表数据的传输。Activity之间的跳转通过Intent类完成，Intent类在跳转过程中还可携带数据。

 

修改activity_main.xml布局文件，添加一个文本框和发送按钮，点击发送按钮时，会将文本框的信息传到FirstActivity，并完成跳转。

<LinearLayout 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"
    tools:context="com.cygoat.myapp.MainActivity" >
	
    <EditText
        android:id="@+id/message"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:hint="@string/hello_world" />
	<Button android:layout_width="wrap_content"
	    android:layout_height="wrap_content"
	    android:text="@string/send_button"
	    android:onClick="sendMessage"/>
</LinearLayout>

 

修改MainActivity.java，添加sendMessage（View）方法，当发送按钮点击时，会调用该方法。该方法会将文本框的消息保存到Intent对象中，并通过Intent实例跳转。代码如下

package com.cygoat.myapp;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.EditText;

public class MainActivity extends Activity {

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
	}

	@Override
	public boolean onCreateOptionsMenu(Menu menu) {
		// Inflate the menu; this adds items to the action bar if it is present.
		getMenuInflater().inflate(R.menu.main, menu);
		return true;
	}

	@Override
	public boolean onOptionsItemSelected(MenuItem item) {
		// Handle action bar item clicks here. The action bar will
		// automatically handle clicks on the Home/Up button, so long
		// as you specify a parent activity in AndroidManifest.xml.
		int id = item.getItemId();
		if (id == R.id.action_settings) {
			return true;
		}
		return super.onOptionsItemSelected(item);
	}
	
	public void sendMessage(View view){
		Intent intent = new Intent(this,FirstActivity.class);
		EditText text = (EditText) findViewById(R.id.message);
		intent.putExtra("message", text.getText().toString());
		startActivity(intent);
	}
}

 

创建activity_first.xml布局，用来展示接收的消息，内容如下

<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.cygoat.myapp.FirstActivity" >

    <TextView
        android:id="@+id/result"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/hello_world" />

</RelativeLayout>

 

创建FirstActivity.java类，该类接收消息并展示。代码如下

package com.cygoat.myapp;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.TextView;

public class FirstActivity extends Activity {

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_first);
		Intent intent = getIntent();
		String message = intent.getStringExtra("message");
		TextView textView = (TextView) findViewById(R.id.result);
		textView.setText("内容为："+message);
	}

	@Override
	public boolean onCreateOptionsMenu(Menu menu) {
		// Inflate the menu; this adds items to the action bar if it is present.
		getMenuInflater().inflate(R.menu.first, menu);
		return true;
	}

	@Override
	public boolean onOptionsItemSelected(MenuItem item) {
		// Handle action bar item clicks here. The action bar will
		// automatically handle clicks on the Home/Up button, so long
		// as you specify a parent activity in AndroidManifest.xml.
		int id = item.getItemId();
		if (id == R.id.action_settings) {
			return true;
		}
		return super.onOptionsItemSelected(item);
	}
}

 

测试如下

 

 
 

源代码如附件