Android 代码规范文档

public String name;
public TextView nameView;
public FrameLayout nameLayout;

// 命名规范附带技巧（当布局中同个类型的控件只有一个的时候，也可以这样命名）
public TextView textView;
public RecyclerView recyclerView;

private String mName;
private TextView mNameView;
private FrameLayout mNameLayout;

// 命名规范附带技巧（当布局中同个类型的控件只有一个的时候，也可以这样命名）
private TextView mTextView;
private RecyclerView mRecyclerView;

// 不规范写法示例
private boolean mIsDebug;
boolean isDebug;

// 规范写法示例
private boolean mDebug;
boolean debug;

static Handler sHandler;

static final String REQUEST_INSTALL_PACKAGES;

public class Activity {

    public static final int RESULT_CANCELED    = 0;
    public static final int RESULT_OK          = -1;

    private Instrumentation mInstrumentation;

    private IBinder mToken;
    private IBinder mAssistToken;

    private Application mApplication;

    /*package*/ Intent mIntent;

    /*package*/ String mReferrer;

    private ComponentName mComponent;

    /*package*/ ActivityInfo mActivityInfo;

    /*package*/ ActivityThread mMainThread;

    Activity mParent;

    boolean mCalled;

    /*package*/ boolean mResumed;

    /*package*/ boolean mStopped;

    boolean mFinished;
    boolean mStartedActivity;

    private boolean mDestroyed;
    private boolean mDoReportFullyDrawn = true;
    private boolean mRestoredFromBundle;

    private final ArrayList<Application.ActivityLifecycleCallbacks> mActivityLifecycleCallbacks =
            new ArrayList<Application.ActivityLifecycleCallbacks>();

    private Window mWindow;

    private WindowManager mWindowManager;

    private CharSequence mTitle;
    private int mTitleColor = 0;


    final Handler mHandler = new Handler();

    final FragmentController mFragments = FragmentController.createController(new HostCallbacks());
}

public class View {

    private View.OnClickListener mListener;

    public void setOnClickListener(OnClickListener listener) {
        mListener = listener;
    }

    public interface OnClickListener {

        void onClick(View v);
    }
}

public class Handler {

    public interface Callback {

        boolean handleMessage(Message msg);
    }
}

public final class PasswordEditText extends EditText implements View.OnTouchListener, View.OnFocusChangeListener, TextWatcher {

    public PasswordEditText(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        setOnTouchListener(this);
        setOnFocusChangeListener(this);
        addTextChangedListener(this);
    }

    @Override
    public void onFocusChange(View view, boolean hasFocus) {
        ......
    }

    @Override
    public boolean onTouch(View view, MotionEvent event) {
        ......
    }

    @Override
    public void onTextChanged(CharSequence s, int start, int before, int count) {
        ......
    }

    @Override
    public void beforeTextChanged(CharSequence s, int start, int count, int after) {
        ......
    }

    @Override
    public void afterTextChanged(Editable s) {
        ......
    }
}

public final class PasswordEditText extends EditText
        implements View.OnTouchListener,
        View.OnFocusChangeListener, TextWatcher {

    public PasswordEditText(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        setOnTouchListener(this);
        setOnFocusChangeListener(this);
        addTextChangedListener(this);
    }

    /**
     * {@link OnFocusChangeListener}
     */

    @Override
    public void onFocusChange(View view, boolean hasFocus) {
        ......
    }

    /**
     * {@link OnTouchListener}
     */

    @Override
    public boolean onTouch(View view, MotionEvent event) {
        ......
    }

    /**
     * {@link TextWatcher}
     */

    @Override
    public void onTextChanged(CharSequence s, int start, int before, int count) {
        ......
    }

    @Override
    public void beforeTextChanged(CharSequence s, int start, int count, int after) {
        ......
    }

    @Override
    public void afterTextChanged(Editable s) {
        ......
    }
}

try {
    Xxx.xxx();
} catch (Exception e) {}

// 捕获这个异常，避免程序崩溃
try {
    // 目前发现在 Android 7.1 主线程被阻塞之后弹吐司会导致崩溃，可使用 Thread.sleep(5000) 进行复现
    // 查看源码得知 Google 已经在 Android 8.0 已经修复了此问题
    // 主线程阻塞之后 Toast 也会被阻塞，Toast 因为显示超时导致 Window Token 失效
    mHandler.handleMessage(msg);
} catch (WindowManager.BadTokenException | IllegalStateException e) {
    // android.view.WindowManager$BadTokenException：Unable to add window -- token android.os.BinderProxy is not valid; is your activity running?
    // java.lang.IllegalStateException：View android.widget.TextView has already been added to the window manager.
    e.printStackTrace();
}

Caused by: java.lang.IllegalArgumentException: You cannot start a load for a destroyed activity
   at com.bumptech.glide.manager.RequestManagerRetriever.assertNotDestroyed(RequestManagerRetriever.java:348)
   at com.bumptech.glide.manager.RequestManagerRetriever.get(RequestManagerRetriever.java:148)
   at com.bumptech.glide.Glide.with(Glide.java:826)

try {
    // Activity 销毁后执行加载图片会触发 crash
    Glide.with(this)
            .load(url)
            .into(mImageView);
} catch (IllegalArgumentException e) {
    // java.lang.IllegalArgumentException: You cannot start a load for a destroyed activity
    e.printStackTrace();
}

if (isFinishing() || isDestroyed()) {
   // Glide：You cannot start a load for a destroyed activity
    return;
}
Glide.with(this)
        .load(url)
        .into(mImageView);

public class IntentKey {

    /** id */
    public static final String ID = "id";
    /** token */
    public static final String TOKEN = "token";
    /** 订单 */
    public static final String ORDER = "order";
    /** 余额 */
    public static final String BALANCE = "balance";
    /** 时间 */
    public static final String TIME = "time";
    /** URL */
    public static final String URL = "url";
    /** 路径 */
    public static final String PATH = "path";
    /** 其他 */
    public static final String OTHER = "other";

    .....
}

public final class WebActivity extends Activity {

    public static void start(Context context, String url) {
        Intent intent = new Intent(context, WebActivity.class);
        intent.putExtra(IntentKey.URL, url);
        context.startActivity(intent);
    }
}

public final class WebActivity extends Activity {

    public static Intent newIntent(Context context, String url) {
        Intent intent = new Intent(context, WebActivity.class);
        intent.putExtra(IntentKey.URL, url);
        return intent;
    }
}

public final class WebFragment extends Fragment {

    public static WebFragment newInstance(String url) {
        WebFragment fragment = new WebFragment();
        Bundle bundle = new Bundle();
        bundle.putString(IntentKey.URL, url);
        fragment.setArguments(bundle);
        return fragment;
    }
}

public final class VideoPlayActivity extends Activity {

    /**
     * 播放参数构建
     */
    public static final class Builder implements Parcelable {

        /** 视频源 */
        private String mVideoSource;
        /** 视频标题 */
        private String mVideoTitle;
        /** 播放进度 */
        private int mPlayProgress;
        /** 手势开关 */
        private boolean mGestureEnabled = true;
        /** 循环播放 */
        private boolean mLoopPlay = false;
        /** 自动播放 */
        private boolean mAutoPlay = true;
        /** 播放完关闭 */
        private boolean mAutoOver = true;

        public Builder() {}

        public Builder setVideoSource(File file) {
            mVideoSource = file.getPath();
            if (mVideoTitle == null) {
                mVideoTitle = file.getName();
            }
            return this;
        }

        public Builder setVideoSource(String url) {
            mVideoSource = url;
            return this;
        }

        private String getVideoSource() {
            return mVideoSource;
        }

        public Builder setVideoTitle(String title) {
            mVideoTitle = title;
            return this;
        }

        private String getVideoTitle() {
            return mVideoTitle;
        }

        public Builder setPlayProgress(int progress) {
            mPlayProgress = progress;
            return this;
        }

        private int getPlayProgress() {
            return mPlayProgress;
        }

        public Builder setGestureEnabled(boolean enabled) {
            mGestureEnabled = enabled;
            return this;
        }

        private boolean isGestureEnabled() {
            return mGestureEnabled;
        }

        public Builder setLoopPlay(boolean enabled) {
            mLoopPlay = enabled;
            return this;
        }

        private boolean isLoopPlay() {
            return mLoopPlay;
        }

        public Builder setAutoPlay(boolean enabled) {
            mAutoPlay = enabled;
            return this;
        }

        public boolean isAutoPlay() {
            return mAutoPlay;
        }

        public Builder setAutoOver(boolean enabled) {
            mAutoOver = enabled;
            return this;
        }

        private boolean isAutoOver() {
            return mAutoOver;
        }

        public void start(Context context) {
            Intent intent = new Intent(context, VideoPlayActivity.class);
            intent.putExtra(IntentKey.VIDEO, this);
            if (!(context instanceof Activity)) {
                intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
            }
            context.startActivity(intent);
        }
    }
}

new VideoPlayActivity.Builder()
        .setVideoTitle("速度与激情特别行动")
        .setVideoSource("http://xxxxx.mp4")
        .start(getAttachActivity());

/**
 *    author : Android 轮子哥
 *    github : https://github.com/getActivity/XXPermissions
 *    time   : 2018/06/15
 *    desc   : 权限请求实体类
 *    doc    : https://developer.android.google.cn/reference/android/Manifest.permission?hl=zh_cn
 *             https://developer.android.google.cn/guide/topics/permissions/overview?hl=zh-cn#normal-dangerous
 */
public final class Permission {
    ....
}

/**
 * 设置请求的对象
 *
 * @param activity          当前 Activity，可以传入栈顶的 Activity
 */
public static XXPermissions with(FragmentActivity activity) {
    return ....;
}

/** 请求的权限组 */
private static final String REQUEST_PERMISSIONS = "request_permissions";

/** 权限回调对象 */
private OnPermissionCallback mCallBack;

// 设置保留实例，不会因为屏幕方向或配置变化而重新创建
fragment.setRetainInstance(true);

// 不规范写法示例
if (view.getVisibility() != 0) {
    return;
}

Intent intent = new Intent("android.settings.APPLICATION_DETAILS_SETTINGS");
startActivity(intent);

// 规范写法示例
if (view.getVisibility() != View.VISIBLE) {
    return;
}

Intent intent = new Intent(Settings.ACTION_APPLICATION_DETAILS_SETTINGS);
startActivity(intent);

public final class UserInfoManager {

    /** 学生 */
    public static final int TYPE_STUDENT = 0;

    /** 老师 */
    public static final int TYPE_TEACHER = 1;

    /** 家长 */
    public static final int TYPE_PATRIARCH = 2;
}

ValueAnimator animator = ValueAnimator.ofInt(0, 100);
animator.setDuration(500);
animator.start();