bt1.setOnClickListener(new OnClickListener() {
public void onClick(View v) {	
Toast.makeText(To.this, "短时间", Toast.LENGTH_SHORT).show();
tView.setText("短时间");
}
});
bt2.setOnClickListener(new OnClickListener() {

public void onClick(View v) {
// TODO Auto-generated method stub
Toast.makeText(To.this, "长时间", Toast.LENGTH_LONG).show();
tView.setText("长时间");
}
});

bt3.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
Dialog ad=new AlertDialog.Builder(To.this)
.setTitle("警告")//设置标题
.setIcon(R.drawable.icon)//设置图片
.setMessage("提示警告")//设置提示信息
.create();
ad.show();
}
});