Android判断程序是否第一次启动

public class Welcome extends Activity {
  private final long SPLASH_LENGTH = 2000;
  Handler handler = new Handler();

  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.farst_img);
    
    //定义一个setting记录APP是几次启动！！！
    SharedPreferences setting = getSharedPreferences("com.example.hr_jie", 0);
    Boolean user_first = setting.getBoolean("FIRST", true);
    if (user_first) {// 第一次则跳转到欢迎页面
      setting.edit().putBoolean("FIRST", false).commit();
      tiaozhuanzhu();
    } else {//如果是第二次启动则直接跳转到主页面
      tiaozhuanfu();
    }
  }
  
  public void tiaozhuanzhu(){ 
  handler.postDelayed(new Runnable() { //使用handler的postDelayed实现延时跳转 
     
      public void run() {  
        Intent intent = new Intent(Welcome.this, Welcome_four.class);  
        startActivity(intent);  
        finish();    
      }  
    }, SPLASH_LENGTH);//2秒后跳转至应用主界面MainActivity 
}
  
  public void tiaozhuanfu(){ 
  handler.postDelayed(new Runnable() {//使用handler的postDelayed实现延时跳转 
     
      public void run() {  
        Intent intent = new Intent(Welcome.this, MainActivity.class);  
        startActivity(intent);  
        finish();    
      }  
    }, SPLASH_LENGTH);//2秒后跳转至应用欢迎界面
}
}