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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