Android實用代碼七段（一）

前言

 這里積累了一些不常見確又很實用的代碼，每收集7條更新一次，希望能對大家有用。

 

聲明

　　歡迎轉載，但請保留文章原始出處:) 
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正文 

1、 精確獲取屏幕尺寸（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、 判斷是否是平板（官方用法）

                
          public  
          static  
          boolean isTablet(Context context) { 
          
         
          return (context.getResources().getConfiguration().screenLayout & Configuration.SCREENLAYOUT_SIZE_MASK) >= Configuration.SCREENLAYOUT_SIZE_LARGE; 
          
    } 
         

 

3、 文字根據狀態更改顏色 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/目錄下

 

4、背景色根據狀態更改顏色 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>

  如果直接給背景色color會報錯。

 

5、 啟動APK的默認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、計算字寬

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

注意如果設置了textStyle，還需要進一步設置TextPaint。