Android实用代码七段（一）

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);
}

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>

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>

5、 启动APK的默认Activity

public 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);
}
}

6、计算字宽

public static float GetTextWidth(String text, float Size) {
TextPaint FontPaint = new TextPaint();
FontPaint.setTextSize(Size);
return FontPaint.measureText(text);
}