android使用代码片段，,1、 精确获取屏幕尺寸

android使用代码片段，,1、 精确获取屏幕尺寸

1、  精确获取屏幕尺寸（例如：3.5、4.0、5.0寸屏幕）     public static double getScreenPhysicalSize(Activity ctx) {        DisplayMetrics dm = new DisplayMetrics();        ctx.getWindowManager().getDefaultDisplay().getMetrics(dm);        double diagonalPixels = Math.sqrt(Math.pow(dm.widthPixels, 2) + Math.pow(dm.heightPixels, 2));        return diagonalPixels / (160 * dm.density);    }一般是7寸以上是平板2、  判断是否是平板（官方用法）public static boolean isTablet(Context context) {    return (context.getResources().getConfiguration().screenLayout & Configuration.SCREENLAYOUT_SIZE_MASK) >= Configuration.SCREENLAYOUT_SIZE_LARGE;}3、  文字根据状态更改颜色 android:textColor <selector xmlns:android="http://schemas.android.com/apk/res/android">    <item android:color="#53c1bd" android:state_selected="true"/>    <item android:color="#53c1bd" android:state_focused="true"/>    <item android:color="#53c1bd" android:state_pressed="true"/>    <item android:color="#777777"/></selector>放在res/color/目录下4、背景色根据状态更改颜色 android:backgroup<selector xmlns:android="http://schemas.android.com/apk/res/android">    <item android:state_selected="true"><shape>            <gradient android:angle="0" android:centerColor="#00a59f" android:endColor="#00a59f" android:startColor="#00a59f" />        </shape></item>    <item android:state_focused="true"><shape>            <gradient android:angle="0" android:centerColor="#00a59f" android:endColor="#00a59f" android:startColor="#00a59f" />        </shape></item>    <item android:state_pressed="true"><shape>            <gradient android:angle="0" android:centerColor="#00a59f" android:endColor="#00a59f" android:startColor="#00a59f" />        </shape></item>    <item><shape>            <gradient android:angle="0" android:centerColor="#00ff00" android:endColor="00ff00" android:startColor="00ff00" />        </shape></item></selector>如果直接给背景色color会报错。5、  启动APK的默认Activitypublic static void startApkActivity(final Context ctx, String packageName) {    PackageManager pm = ctx.getPackageManager();    PackageInfo pi;    try {        pi = pm.getPackageInfo(packageName, 0);        Intent intent = new Intent(Intent.ACTION_MAIN, null);        intent.addCategory(Intent.CATEGORY_LAUNCHER);        intent.setPackage(pi.packageName);        List<ResolveInfo> apps = pm.queryIntentActivities(intent, 0);        ResolveInfo ri = apps.iterator().next();        if (ri != null) {            String className = ri.activityInfo.name;            intent.setComponent(new ComponentName(packageName, className));            ctx.startActivity(intent);        }    } catch (NameNotFoundException e) {        Log.e("startActivity", e);    }}7、计算字宽public static float GetTextWidth(String text, float Size) {    TextPaint FontPaint = new TextPaint();    FontPaint.setTextSize(Size);    return FontPaint.measureText(text);}    注意如果设置了textStyle，还需要进一步设置TextPaint。//该片段来自于http://byrx.net