<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:tools="http://schemas.android.com/tools"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:paddingBottom="@dimen/activity_vertical_margin"
  android:paddingLeft="@dimen/activity_horizontal_margin"
  android:paddingRight="@dimen/activity_horizontal_margin"
  android:paddingTop="@dimen/activity_vertical_margin"
  tools:context=".MainActivity" >
  <TextView
    android:id="@+id/textView1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@string/hello_world" />
  <Button
    android:id="@+id/button1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentRight="true"
    android:layout_alignTop="@+id/textView1"
    android:layout_marginRight="61dp"
    android:text="确定" />
</RelativeLayout>

package com.example.ep.toast;
import android.os.Bundle;
import android.app.Activity;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
public class MainActivity extends Activity {
  private TextView txtview1;
  private Button btn1;
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    //绑定文字标签控件
    txtview1=(TextView)findViewById(R.id.textView1);
    //绑定按钮控件
    btn1=(Button)findViewById(R.id.button1);
    //添加一个点击事件监听器并实例化一个点击事件的监听
    btn1.setOnClickListener(new OnClickListener() {
      @Override
      public void onClick(View v) {
        //点击按钮后设置文字标签
        txtview1.setText("Joven");
        //点击按钮后弹出提示框，里面的参数是（绑定活动，提示内容，显示时间）
        Toast.makeText(MainActivity.this, "Joven", Toast.LENGTH_LONG).show();
      }
    });
  }
}