【发布时间】：2014-09-09 07:43:36
【问题描述】：
我试图编写一个程序，用于将文本从主要活动发送到另一个活动“DisplayMessageActivity”。但是，当我在我的 android 手机中安装该应用程序时，按下按钮后，它会崩溃并显示一条消息“不幸的是应用程序已停止”
我的不同文件如下...(eclipse)
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MainActivity.java 文件...
包 com.example.practice3;
导入 android.content.Intent; 导入android.os.Bundle； 导入android.support.v4.app.Fragment； 导入android.support.v7.app.ActionBarActivity； 导入 android.view.LayoutInflater； 导入 android.view.Menu； 导入android.view.MenuItem； 导入android.view.View； 导入android.view.ViewGroup； 导入 android.widget.EditText； 公共类 MainActivity 扩展 ActionBarActivity { public final static String EXTRA_MESSAGE = "com.example.myfirstapp.MESSAGE";
@Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); if (savedInstanceState == null) { getSupportFragmentManager().beginTransaction() .add(R.id.container, new PlaceholderFragment()) .commit(); } } @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); } /** * A placeholder fragment containing a simple view. */ public static class PlaceholderFragment extends Fragment { public PlaceholderFragment() { } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View rootView = inflater.inflate(R.layout.fragment_main, container, false); return rootView; } } public void sendMessage(View view) { 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); }}
2.fragment_main.xml 文件
<?xml version="1.0" encoding="utf-8"?>
<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"
android:orientation="horizontal">
<EditText android:id="@+id/edit_message"
android:layout_weight="1"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:hint="@string/edit_message" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/button_send"
android:onClick="sendMessage"
/>
</LinearLayout>
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DisplayMessageActivity.java 文件
package com.example.practice3; import android.content.Intent; import android.os.Bundle; import android.support.v4.app.Fragment; import android.support.v7.app.ActionBarActivity; import android.view.LayoutInflater; import android.view.Menu; import android.view.MenuItem; import android.view.View; import android.view.ViewGroup; import android.widget.TextView; public class DisplayMessageActivity extends ActionBarActivity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_display_message); 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); // Set the text view as the activity layout setContentView(textView); if (savedInstanceState == null) { getSupportFragmentManager().beginTransaction() .add(R.id.container, new PlaceholderFragment()).commit(); } } @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) { // 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); } /** * A placeholder fragment containing a simple view. */ public static class PlaceholderFragment extends Fragment { public PlaceholderFragment() { } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View rootView = inflater.inflate(R.layout.fragment_display_message, container, false); return rootView; } }}
4.fragment_display_message.xml 文件
<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.example.practice3.DisplayMessageActivity$PlaceholderFragment" >
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/hello_world" />
</RelativeLayout>
5.Strings.xml 文件
<?xml version="1.0" encoding="utf-8"?>
<resources>
<string name="app_name">My First App</string>
<string name="edit_message">Enter a message</string>
<string name="button_send">Send</string>
<string name="action_settings">Settings</string>
<string name="title_activity_main">MainActivity</string>
<string name="title_activity_display_message">DisplayMessageActivity</string>
<string name="hello_world">Hello world!</string>
</resources>
【问题讨论】：
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你能发布 logcat 的输出吗？
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您是否在清单中添加了活动名称？
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发布你的安卓清单
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先生，我已经在 eclipse 上构建了这个并且没有在 emulator 上尝试过，因为它需要太长时间。没有错误。我已将其直接加载到我的 android 手机中，然后安装它。当我启动它时，第一个主要活动开始，然后显示一个按钮和一个文本字段，当我按下按钮时，应用程序崩溃并显示消息“不幸的是应用程序已停止”