请问静态Handler里Toast.makeText()方法的第一个参数怎么设置？

Question

最近在写的程序需要Service和Activity通信，于是想到将MainActivity里面的dataHandler改为static，再在Service里面调用sendMessage()方法。但是handler改为static后，makeText()又报错了，查了一些解决方法都没什么用，请问这个要怎么改？谢谢！

代码：

 public static Handler dataHandler = new Handler(){
        public void handleMessage(android.os.Message msg) {
            if (msg.what == 0) {
                // 处理服务器返回的id，并分配给用户
                try {
                    JSONObject jsonObject = new JSONObject(msg.obj.toString());
                    user.setId(jsonObject.getInt("id"));
                    Toast.makeText(MainActivity.this, "成功连接到服务器,id = " + user.getId(), Toast.LENGTH_SHORT).show();
                } catch (JSONException e) {
                    // TODO Auto-generated catch block
                    Toast.makeText(MainActivity.this, "用户id读取错误！", Toast.LENGTH_SHORT).show();
                    e.printStackTrace();
                }       
            } 
            ...
    }

MainActivity.this 报错：No enclosing instance of the type MainActivity is accessible in scope

Answer 1

定义一个静态的activity，this.activity=this; 然后把toast里面 的第一个参数换成activity；
private static Activity ac;
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ac = this;
}

            public static Handler handler = new Handler(new Handler.Callback() {
    @Override
    public boolean handleMessage(Message msg) {
        Toast.makeText(ac, "用户id读取错误！", Toast.LENGTH_SHORT).show();
        return false;
    }
});