Android应用挂起

Question

Hey i'm brand new to programming and i need some help, i'm doing a project for school and it's an android app where the user inputs words to a text field and then those words are used to create a story, like mad libs. I can not seem to see what is wrong with my code here when i debug on my phone it just shows a white screen. Could someone point out to me what i'm doing wrong? thanks...

MainActivity.java:

package com.joe.madlibs;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class MainActivity extends Activity {

    EditText Noun, Adj, Name, Verb, Verb2, Noun2, Adj2;
    Button Submit;
    TextView Story;


    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Noun = (EditText) findViewById(R.id.noun1);
        Adj = (EditText) findViewById(R.id.adjective1);
        Name = (EditText) findViewById(R.id.name1);
        Verb = (EditText) findViewById(R.id.verb1);
        Verb2 = (EditText) findViewById(R.id.verb2);
        Noun2 = (EditText) findViewById(R.id.noun2);
        Adj2 = (EditText) findViewById(R.id.adj2);
        String noun = Noun.getText().toString();
        String adj = Adj.getText().toString();
        String name = Name.getText().toString();
        String verb = Verb.getText().toString();
        String verb2 = Verb2.getText().toString();
        String noun2 = Noun2.getText().toString();
        String adj2 = Adj2.getText().toString();
        Submit.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub

            }
        });

    }

    @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;
    }

}

activity_main.xml
<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=".MainActivity" >

    <LinearLayout
        android:id="@+id/linearLayout1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="vertical" >
    </LinearLayout>

    <EditText
        android:id="@+id/noun1"
        android:layout_width="140dp"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/linearLayout1"
        android:layout_alignTop="@+id/linearLayout1"
        android:ems="10"
        android:hint="@string/noun" >
    </EditText>

    <EditText
        android:id="@+id/verb1"
        android:layout_width="140dp"
        android:layout_height="wrap_content"
        android:layout_alignBaseline="@+id/name1"
        android:layout_alignBottom="@+id/name1"
        android:layout_alignRight="@+id/storyBox"
        android:ems="10"
        android:hint="@string/verb" />

    <EditText
        android:id="@+id/adjective1"
        android:layout_width="140dp"
        android:layout_height="wrap_content"
        android:layout_alignBaseline="@+id/noun1"
        android:layout_alignBottom="@+id/noun1"
        android:layout_alignLeft="@+id/verb1"
        android:ems="10"
        android:hint="@string/adjective" />

    <EditText
        android:id="@+id/name1"
        android:layout_width="140dp"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/noun1"
        android:layout_below="@+id/noun1"
        android:ems="10"
        android:hint="@string/name" />

    <EditText
        android:id="@+id/verb2"
        android:layout_width="140dp"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/name1"
        android:layout_below="@+id/name1"
        android:ems="10"
        android:hint="@string/verb" />

    <EditText
        android:id="@+id/adj2"
        android:layout_width="140dp"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/verb1"
        android:layout_below="@+id/verb1"
        android:ems="10"
        android:hint="Adjective" />

    <EditText
        android:id="@+id/noun2"
        android:layout_width="140dp"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/verb2"
        android:layout_below="@+id/verb2"
        android:ems="10"
        android:hint="Noun" />


    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_centerVertical="true"
        android:text="Click here to get your story!" />

    <TextView
        android:id="@+id/storyBox"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/noun2"
        android:layout_below="@+id/button1"
        android:layout_marginTop="18dp"
        android:text="This is where your story will go!"
        android:textAppearance="?android:attr/textAppearanceLarge" />

</RelativeLayout>


Manifest.xml:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.Joe.madlibs"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="17" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.Joe.madlibs.MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

Answer 1

Umm... where are you instantiating your Submit button before trying to set an onClickListener on it? I see where you declare it, but you aren't instantiating it.

Add:

Submit = (Button)findViewById(R.id.button1);

right before

Submit.setOnClickListener(new View.OnClickListener() {

and watch. It's gonna be like magic.

One more thing about coding conventions (style): when you name your instance variables, use the headlessCamelCase convention. Names with CamelCase/InitCaps (first letter of each word capitalized) should only be used when you name your class (the pattern for an object) as opposed to when you refer to an instance of that class (the actual object).

Wrong:

// An instance of Button class
Button Submit;

Right:

// An instance of Button class:
Button submit;

When it comes to compound names (more than one word), headlessCamelCase means you capitalize the first letter of each word, except the first word.

Right:

// An instance of Button class:
Button myVeryElderlyMotherJustSatUponNapoleonsSubmitButton;