Android应用不断在模拟器和Nexus 10中崩溃

Question

This app keeps on crashing inside the emulator (for which I have allocated 700 MB for RAM, and is a Nexus 4), and when I try loading it onto my Nexus 10, and Galaxy S3. I think it is because of several errors in Java on how to switch Android activities, for which I'm warnings from, but not errors. This is the code:

    package com.example.ldsm2;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.View;

public class Instructions extends Activity {

/** Called when the user clicks the Send button */
public void Ldsm (View view) {
    Object Intent = startActivity(Ldsm.class);  
}

private com.example.ldsm2.intent startActivity(
        Class<Ldsm> class1) {
    // TODO Auto-generated method stub
    return null;
}

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

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

}

Because the other activities just have a different activity to switch to, I simply copied the code to the other activities' Java source code files, but changed the activities to switch to (the students will click on a button and it will send them to another problem to solve).

However, this seems like this is not the only problem in the app. The app is supposed to display images, but there is another warning that comes up for that function as well. This is the XML code, once again copied to the other activities files because they just need to display another image.

    <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=".Ldsm" >

<EditText
    android:id="@+id/launch_codes"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:hint="@string/enter_launch_codes"
    android:imeActionLabel="@string/launch"
    android:inputType="number" />

<Button
    android:id="@+id/button2"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentBottom="true"
    android:layout_alignParentRight="true"
    android:onClick="methodName"
    android:text="@string/instructions" />

<Button
    android:id="@+id/button1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignBottom="@+id/launch_codes"
    android:layout_alignParentRight="true"
    android:onClick="modeon"
    android:text="@string/button_send" />

<ImageView
    android:id="@+id/imageView1"
    android:layout_width="50dp"
    android:layout_height="50dp"
    android:layout_below="@+id/launch_codes"
    android:layout_marginTop="141dp"
    android:layout_toLeftOf="@+id/button2"
    android:src="@drawable/ic_pro1" android:contentDescription="TODO"/>

These are the warnings that come up in the Eclipse problems tab. For the XML code, this is the error that comes up: "Description: The value of the local variable Intent is not used line 16 Java Problem, and for the Java code: Description Resource Path Location Type [Accessibility] Missing contentDescription attribute on image line 37 Android Lint Problem.

Finally, this is the error that comes up when I try launching the app inside the emulator.

Answer 1

You need to use LogCat to see what it says. There will be some clue as to what is happening.

[Accessibility] Missing contentDescription attribute  

is for the visually impaired. This value is read out by screen readers. Basically what it is saying is that there is a possibility of an accessibility bug.

The value of the local variable Intent is not used  

This tells you that although you have assigned a value to your variable, you have never used it anywhere in your code. You may safely delete this unless you plan on using it. Since it is an Intent , I guess you are planning on starting some other Activity