Android实用代码七段（一）

正文

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);

}

}

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。