当我在手机上启动活动时，它说应用程序没有响应。问题是后退按钮，我似乎无法对其进行编程以使其从 textView 收集以前的文本。
活动的 XML 代码
<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:background="@drawable/background"
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=".Author" >
<TextView
android:id="@+id/textView1"
android:layout_width="300dp"
android:layout_height="300dp"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:background="@drawable/button_shape"
android:text="@string/Getstarted"
android:textColor="#FFFFFF"
android:textSize="23sp" />
<ImageButton
android:id="@+id/next"
android:layout_width="90dp"
android:layout_height="50dp"
android:layout_alignRight="@+id/textView1"
android:layout_below="@+id/textView1"
android:layout_marginTop="14dp"
android:background="@drawable/button_shape"
android:contentDescription="@string/Next"
android:onClick="NextQuote"
android:src="@drawable/navigationnextitem" />
<ImageButton
android:id="@+id/share"
android:layout_width="90dp"
android:layout_height="50dp"
android:layout_alignTop="@+id/next"
android:layout_centerHorizontal="true"
android:background="@drawable/button_shape"
android:contentDescription="@string/share"
android:onClick="Sharing"
android:src="@drawable/socialshare" />
<ImageButton
android:id="@+id/back"
android:layout_width="90dp"
android:layout_height="50dp"
android:layout_alignLeft="@+id/textView1"
android:layout_alignTop="@+id/next"
android:background="@drawable/button_shape"
android:contentDescription="@string/Back"
android:onClick="PreviousQuote"
android:src="@drawable/navigationpreviousitem" />
</RelativeLayout>
活动的 Java 代码
package com.android.motivateme3;
import java.util.Random;
import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.ImageButton;
import android.widget.TextView;
import android.support.v4.app.NavUtils;
import android.annotation.TargetApi;
import android.content.Intent;
import android.os.Build;
public class Author extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_author);
// 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);
Button NextQuote = (Button)findViewById(R.id.next);
final TextView display = (TextView) findViewById(R.id.textView1);
NextQuote.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// TODO Auto-generated method stub
Random numGen = new Random();
int rNumber = numGen.nextInt(10);
if (rNumber == 0)
{
display.setText(R.string.Author1);
}
else if (rNumber == 1)
{
display.setText(R.string.Author2);
}
else if (rNumber == 2)
{
display.setText(R.string.Author3);
}
else if (rNumber == 3)
{
display.setText(R.string.Author4);
}
else if (rNumber == 4)
{
display.setText(R.string.Author5);
}
else if (rNumber == 5)
{
display.setText(R.string.Author6);
}
else if (rNumber == 6)
{
display.setText(R.string.Author7);
}
else if (rNumber == 7)
{
display.setText(R.string.Author8);
}
else if (rNumber == 8)
{
display.setText(R.string.Author9);
}
else if (rNumber == 9)
{
display.setText(R.string.Author10);
} }
});
}
ImageButton Sharing = (ImageButton)findViewById(R.id.share);
Sharing.setOnClickListener(new View.OnClickListener() {
public void onClick(View v){
TextView text = (TextView)findViewById(R.id.textView1);
String quote = text.getText().toString();{
Intent shareIntent = new Intent(android.content.Intent.ACTION_SEND);
shareIntent.setType("plain/text");
shareIntent.putExtra(android.content.Intent.EXTRA_SUBJECT, "This is a great quote (from the Motivate Me! app)");
shareIntent.putExtra(android.content.Intent.EXTRA_TEXT, quote);
startActivity(Intent.createChooser(shareIntent, "Share via:"));}}});
Button BackQuote = (Button)findViewById(R.id.back);
final TextView display = (TextView) findViewById(R.id.textView1);
BackQuote.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
String prev = (String) display.getText();
display.setText(prev);
}
});}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.author, 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);
}
}
这是堆栈跟踪
04-03 14:29:34.174: E/AndroidRuntime(17383): at android.app.ActivityThread.main(ActivityThread.java:4441)
04-03 14:29:34.174: E/AndroidRuntime(17383): at java.lang.reflect.Method.invokeNative(Native Method)
04-03 14:29:34.174: E/AndroidRuntime(17383): at java.lang.reflect.Method.invoke(Method.java:511)
04-03 14:29:34.174: E/AndroidRuntime(17383): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:823)
04-03 14:29:34.174: E/AndroidRuntime(17383): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:590)
04-03 14:29:34.174: E/AndroidRuntime(17383): at dalvik.system.NativeStart.main(Native Method)
04-03 14:29:34.174: E/AndroidRuntime(17383): Caused by: java.lang.ClassCastException: android.widget.ImageButton cannot be cast to android.widget.Button
04-03 14:29:34.174: E/AndroidRuntime(17383): at com.android.motivateme3.Author.setupActionBar(Author.java:36)
04-03 14:29:34.174: E/AndroidRuntime(17383): at com.android.motivateme3.Author.onCreate(Author.java:25)
04-03 14:29:34.174: E/AndroidRuntime(17383): at android.app.Activity.performCreate(Activity.java:4465)
04-03 14:29:34.174: E/AndroidRuntime(17383): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
04-03 14:29:34.174: E/AndroidRuntime(17383): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1931)
04-03 14:29:34.174: E/AndroidRuntime(17383): ... 11 more
04-03 14:29:41.664: I/Process(17383): Sending signal. PID: 17383 SIG: 9