@Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        //定位textView1 根据ID找到控件

        TextView tv1 = (TextView) this.findViewById(R.id.textView1);

        //对控件进行赋值，改变内容

        tv1.setText("你好，android一班");

    }

 1 package com.example.helloword;

 2

 3

 4 import android.app.Activity;

 5 import android.os.Bundle;

 6 import android.view.Menu;

 7 import android.view.MenuItem;

 8 import android.widget.TextView;

 9

10

11 public class MainActivity extends Activity {

12

13     @Override

14     protected void onCreate(Bundle savedInstanceState) {

15         super.onCreate(savedInstanceState);

16         setContentView(R.layout.activity_main);

17

18         TextView tv1 = (TextView) this.findViewById(R.id.textView1);

19

20         tv1.setText("你好，Android 1班");

21     }

22

23

24     @Override

25     public boolean onCreateOptionsMenu(Menu menu) {

26         getMenuInflater().inflate(R.menu.main, menu);

27         return true;

28     }

29

30     @Override

31     public boolean onOptionsItemSelected(MenuItem item) {

32         int id = item.getItemId();

33         if (id == R.id.action_settings) {

34             return true;

35         }

36         return super.onOptionsItemSelected(item);

37     }

38 }