本文共 2286 字，大约阅读时间需要 7 分钟。

package com.example.helloworld;import android.support.v7.app.ActionBarActivity;import android.support.v4.app.Fragment;import android.os.Bundle;import android.os.Message;import android.view.LayoutInflater;import android.view.Menu;import android.view.MenuItem;import android.view.View;import android.view.ViewGroup;import android.widget.Toast;import android.os.Handler;public class MainActivity extends ActionBarActivity {    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);    	Message msg2 = new Message();    	msg2.what = 1;    	mHandler2.sendMessage(msg2);                if (savedInstanceState == null) {            getSupportFragmentManager().beginTransaction()                    .add(R.id.container, new PlaceholderFragment())                    .commit();        }    }    private Handler mHandler2 = new Handler(){    	public void handleMessage(Message msg){    		int what = msg.what;    		boolean down = (what==1?true:false);    		Toast toast=Toast.makeText(getApplicationContext(), "今天天气很好"+down, Toast.LENGTH_SHORT);         	toast.show();    		}    	};    @Override    public boolean onCreateOptionsMenu(Menu menu) {                // Inflate the menu; this adds items to the action bar if it is present.        getMenuInflater().inflate(R.menu.main, menu);        return true;    }    @Override    public boolean onOptionsItemSelected(MenuItem item) {        // Handle action bar item clicks here. The action bar will        // automatically handle clicks on the Home/Up button, so long        // as you specify a parent activity in AndroidManifest.xml.        int id = item.getItemId();        if (id == R.id.action_settings) {            return true;        }        return super.onOptionsItemSelected(item);    }        /**     * A placeholder fragment containing a simple view.     */    public static class PlaceholderFragment extends Fragment {        public PlaceholderFragment() {        }        @Override        public View onCreateView(LayoutInflater inflater, ViewGroup container,                Bundle savedInstanceState) {            View rootView = inflater.inflate(R.layout.fragment_main, container, false);            return rootView;        }    }}

转载地址：https://linus.blog.csdn.net/article/details/34410951 如侵犯您的版权，请留言回复原文章的地址，我们会给您删除此文章，给您带来不便请您谅解！