如何让用户第一次在启动时选择设置？

Question

如果没有默认设置，如何设置共享首选项以显示警告框。

public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        /* RR - Restore Prefrences */
         SharedPreferences settings =
         this.getSharedPreferences("com.sample.test",Context.MODE_PRIVATE);
         Boolean isBackgroundWhite = settings.getBoolean("BgColor", true);
             //triggerAlert();
}

Answer 1

使用SharedPreferences.contains()测试是否已设置首选项。如果没有，请显示您的对话框。

if(!settings.contains("BgColor")){

    // Make a call to your dialog code here.  
}

Answer 2

当用户第一次启动应用程序时，使用SharedPreferences.contains检查是否包含SharedPreference包含密钥：

     SharedPreferences settings =
     this.getSharedPreferences("com.sample.test",Context.MODE_PRIVATE);

     if (settings.contains("BgColor")) {
        // means key is present in preference 
        //so no need to show settings
      }else{
         // key not present in preference so 
         // store key in preference and show setting
      }

Answer 3

if (this.getSharedPreferences("com.sample.test",Context.MODE_PRIVATE).getBoolean
    ("firstLaunch", true)){ //Display your dialog settings
    this.getSharedPreferences("com.sample.test",Context.MODE_PRIVATE).edit.
        setBoolean ("firstLaunch", false).commit;
}