I’ve been following the Android tutorials and created MyFirstApp (see http://developer.android.com/training/basics/firstapp/index.html) and I can launch the app ok on the emulator, but upon entering a message and hitting “send” I get an IllegalStateException caused by a NullPointerException at this line in the below code:
String message = editText.getText().toString();
Upon debugging, it is clear that editText is null at this point, but I cannot see why, or anything I’ve missed in the tutorial.
My MainActivity class:
package com.example.myfirstapp;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.widget.EditText;
/**
* <p>Main Activity class for the App</p>
*
* @author - thebloodguy
*/
public class MainActivity extends Activity {
//~ ----------------------------------------------------------------------------------------------------------------
//~ Static fields/initializers
//~ ----------------------------------------------------------------------------------------------------------------
/** Key to the extra message data in the sendMessage intent */
public static final String EXTRA_MESSAGE = "com.example.myfirstapp.MESSAGE";
//~ ----------------------------------------------------------------------------------------------------------------
//~ Methods
//~ ----------------------------------------------------------------------------------------------------------------
/**
* {@inheritDoc}
*/
@Override
public boolean onCreateOptionsMenu(Menu menu) {
/* Inflate the menu; this adds items to the action bar if it is present */
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
/**
* <p>Send a message using the data in the {@link View}</p>
*
* @param view - the {@link View} object representing the state of the view when the message is sent
*/
public void sendMessage(View view) {
Intent intent = new Intent(this, DisplayMessageActivity.class);
EditText editText = (EditText) view.findViewById(R.id.edit_message);
String message = editText.getText().toString(); // This is the guilty line
intent.putExtra(EXTRA_MESSAGE, message);
startActivity(intent);
}
/**
* {@inheritDoc}
*/
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
}
My activity_main.xml:
<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=".MainActivity"
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>
and the LogCat output:
12-21 10:02:32.210: E/Trace(621): error opening trace file: No such file or directory (2)
12-21 10:02:32.250: W/ActivityThread(621): Application com.example.myfirstapp is waiting for the debugger on port 8100...
12-21 10:02:32.270: I/System.out(621): Sending WAIT chunk
12-21 10:02:32.280: I/dalvikvm(621): Debugger is active
12-21 10:02:32.480: I/System.out(621): Debugger has connected
12-21 10:02:32.480: I/System.out(621): waiting for debugger to settle...
12-21 10:02:32.680: I/System.out(621): waiting for debugger to settle...
12-21 10:02:32.889: I/System.out(621): waiting for debugger to settle...
12-21 10:02:33.091: I/System.out(621): waiting for debugger to settle...
12-21 10:02:33.290: I/System.out(621): waiting for debugger to settle...
12-21 10:02:33.534: I/System.out(621): waiting for debugger to settle...
12-21 10:02:33.796: I/System.out(621): waiting for debugger to settle...
12-21 10:02:33.990: I/System.out(621): waiting for debugger to settle...
12-21 10:02:34.204: I/System.out(621): debugger has settled (1353)
12-21 10:02:35.429: D/gralloc_goldfish(621): Emulator without GPU emulation detected.
12-21 10:05:11.510: I/Choreographer(621): Skipped 94 frames! The application may be doing too much work on its main thread.
12-21 10:05:13.850: I/Choreographer(621): Skipped 35 frames! The application may be doing too much work on its main thread.
12-21 10:05:15.571: I/Choreographer(621): Skipped 38 frames! The application may be doing too much work on its main thread.
12-21 10:06:53.724: D/AndroidRuntime(621): Shutting down VM
12-21 10:06:53.724: W/dalvikvm(621): threadid=1: thread exiting with uncaught exception (group=0x40a13300)
12-21 10:06:53.840: E/AndroidRuntime(621): FATAL EXCEPTION: main
12-21 10:06:53.840: E/AndroidRuntime(621): java.lang.IllegalStateException: Could not execute method of the activity
12-21 10:06:53.840: E/AndroidRuntime(621): at android.view.View$1.onClick(View.java:3591)
12-21 10:06:53.840: E/AndroidRuntime(621): at android.view.View.performClick(View.java:4084)
12-21 10:06:53.840: E/AndroidRuntime(621): at android.view.View$PerformClick.run(View.java:16966)
12-21 10:06:53.840: E/AndroidRuntime(621): at android.os.Handler.handleCallback(Handler.java:615)
12-21 10:06:53.840: E/AndroidRuntime(621): at android.os.Handler.dispatchMessage(Handler.java:92)
12-21 10:06:53.840: E/AndroidRuntime(621): at android.os.Looper.loop(Looper.java:137)
12-21 10:06:53.840: E/AndroidRuntime(621): at android.app.ActivityThread.main(ActivityThread.java:4745)
12-21 10:06:53.840: E/AndroidRuntime(621): at java.lang.reflect.Method.invokeNative(Native Method)
12-21 10:06:53.840: E/AndroidRuntime(621): at java.lang.reflect.Method.invoke(Method.java:511)
12-21 10:06:53.840: E/AndroidRuntime(621): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
12-21 10:06:53.840: E/AndroidRuntime(621): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
12-21 10:06:53.840: E/AndroidRuntime(621): at dalvik.system.NativeStart.main(Native Method)
12-21 10:06:53.840: E/AndroidRuntime(621): Caused by: java.lang.reflect.InvocationTargetException
12-21 10:06:53.840: E/AndroidRuntime(621): at java.lang.reflect.Method.invokeNative(Native Method)
12-21 10:06:53.840: E/AndroidRuntime(621): at java.lang.reflect.Method.invoke(Method.java:511)
12-21 10:06:53.840: E/AndroidRuntime(621): at android.view.View$1.onClick(View.java:3586)
12-21 10:06:53.840: E/AndroidRuntime(621): ... 11 more
12-21 10:06:53.840: E/AndroidRuntime(621): Caused by: java.lang.NullPointerException
12-21 10:06:53.840: E/AndroidRuntime(621): at com.example.myfirstapp.MainActivity.sendMessage(MainActivity.java:61)
12-21 10:06:53.840: E/AndroidRuntime(621): ... 14 more
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