如何从Java文件（Android）创建.xml文件？

Question

So i have this java file which basically creates a list of menu items that will take me to that specific activity. I created the list in java but did not create an .xml file when creating the list. Normally, when creating a new activity, android creates an .xml and java file for both. I only created a java file for it. Can android auto generate an .xml file for my menu class or do i have to recreate it?

Code:

Menu.java

package com.AthleteProgram.x.athleteprogram;

import android.app.ListActivity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.ListView;

public class Menu extends ListActivity{

String classes [] = {"AddAthlete", "Email"};

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    ArrayAdapter<String> adapter = new ArrayAdapter<String>(Menu.this, android.R.layout.simple_list_item_1, classes);
    setListAdapter(adapter);

}

@Override
protected void onListItemClick(ListView l, View v, int position, long id) {
    super.onListItemClick(l, v, position, id);

    String listPosition = classes[position];
    try {
        Class myClass = Class.forName("com.AthleteProgram.x.athleteprogram." + listPosition);
        Intent intent = new Intent(Menu.this, myClass);
        startActivity(intent);
    } catch (ClassNotFoundException e) {
        e.printStackTrace();
    }
}

}

I tried to create a menu.xml but to no avail:

<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="vertical"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin"
tools:context="com.AthleteProgram.x.athleteprogram.Menu">

<TextView
    android:text="@string/hello_world"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="center"/>

</LinearLayout>

What do I do to get a visual .xml file so I can see exactly what I am working with? Thank you!

Answer 1

You are missing the part that adds the xml to your class

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    setContentView(R.layout.menu);    //This line add the view to your activity

    ArrayAdapter<String> adapter = new ArrayAdapter<String>(Menu.this, android.R.layout.simple_list_item_1, classes);
    setListAdapter(adapter);

}

Answer 2

You can also create your layout separately by doing right click on res -> New -> Android resource file . Give a name to it and set its Resource type value to "layout".

Then in your Menu.java file add this line setContentView(R.layout.menu); within onCreate method after super.onCreate(savedInstanceState); .