如何使用android开发实现hello world项目

这篇文章主要介绍如何使用android开发实现hello world项目，文中介绍的非常详细，具有一定的参考价值，感兴趣的小伙伴们一定要看完！

最近开始在学android开发，这是我的第一个项目 --hello world！

public class MainActivity extends Activity {    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        //设置activity的布局-->res/layout/activity_main.xml        setContentView(R.layout.activity_main);    }    @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;    }                                                                                                    }

android的主activity类，activity类是android用来显示用户界面的类。

public final class R {    public static final class attr {    }    public static final class dimen {        /**  Default screen margins, per the Android Design guidelines.         Customize dimensions originally defined in res/values/dimens.xml (such as         screen margins) for sw720dp devices (e.g. 10" tablets) in landscape here.                                                                                */        public static final int activity_horizontal_margin=0x7f040000;        public static final int activity_vertical_margin=0x7f040001;    }    public static final class drawable {        public static final int ic_launcher=0x7f020000;    }    public static final class id {        public static final int action_settings=0x7f080000;    }    public static final class layout {        public static final int activity_main=0x7f030000;    }    public static final class menu {        public static final int main=0x7f070000;    }    public static final class string {        public static final int action_settings=0x7f050001;        public static final int app_name=0x7f050000;        public static final int hello_world=0x7f050002;    }    public static final class style {        /**        Base application theme, dependent on API level. This theme is replaced        by AppBaseTheme from res/values-vXX/styles.xml on newer devices.                                                                                   Theme customizations available in newer API levels can go in            res/values-vXX/styles.xml, while customizations related to            backward-compatibility can go here.                                                                                   Base application theme for API 11+. This theme completely replaces        AppBaseTheme from res/values/styles.xml on API 11+ devices.                                                                        API 11 theme customizations can go here.        Base application theme for API 14+. This theme completely replaces        AppBaseTheme from BOTH res/values/styles.xml and        res/values-v11/styles.xml on API 14+ devices.                                                                        API 14 theme customizations can go here.         */        public static final int AppBaseTheme=0x7f060000;        /**  Application theme. All customizations that are NOT specific to a particular API-level can go here.         */        public static final int AppTheme=0x7f060001;    }}

这是R.java，这个类有eclipse自动生成，不需要开发者手动写，是用来为组件，资源注册id的，便于

在activity中找到相应资源的引用

这是android的布局文件，控制用户UI

这是android应用的清单文件，相当于windows下的注册表

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