protected void dialog() {
  AlertDialog.Builder builder = new Builder(Main.this);
  builder.setMessage("确认退出吗？");
  builder.setTitle("提示");
  builder.setPositiveButton("确认", new OnClickListener() {
    @Override
    public void onClick(DialogInterface dialog, int which) {
      dialog.dismiss();
      Main.this.finish();
    }
  });
  builder.setNegativeButton("取消", new OnClickListener() {
    @Override
    public void onClick(DialogInterface dialog, int which) {
      dialog.dismiss();
    }
  });
  builder.create().show();
}

public boolean onKeyDown(int keyCode, KeyEvent event) {
  if (keyCode == KeyEvent.KEYCODE_BACK && event.getRepeatCount() == 0) {
    dialog();
  }
  return false;
}

Dialog dialog = new AlertDialog.Builder(this)
    .setIcon( android.R.drawable.btn_star)
    .setTitle("喜好调查")
    .setMessage("你喜欢李连杰的电影吗？")
    .setPositiveButton("很喜欢",new OnClickListener() {
        @Override
        public void onClick(DialogInterface dialog, int which) {
          // TODO Auto-generated method stub
          Toast.makeText(Main.this, "我很喜欢他的电影。",Toast.LENGTH_LONG).show();
        }
      })
    .setNegativeButton("不喜欢", new OnClickListener() {
        @Override
        public void onClick(DialogInterface dialog, int which) {
           // TODO Auto-generated method stub
          Toast.makeText(Main.this, "我不喜欢他的电影。", Toast.LENGTH_LONG).show();
        }
      })
    .setNeutralButton("一般", new OnClickListener() {
         @Override
        public void onClick(DialogInterface dialog, int which) {
           // TODO Auto-generated method stub
          Toast.makeText(Main.this, "谈不上喜欢不喜欢。", Toast.LENGTH_LONG).show();
         }
      })
    .create();
dialog.show();

new AlertDialog.Builder(this)
    .setTitle("请输入")
    .setIcon(android.R.drawable.ic_dialog_info)
    .setView(new EditText(this))
    .setPositiveButton("确定", null)
    .setNegativeButton("取消", null)
    .show();

new AlertDialog.Builder(this)
    .setTitle("复选框")
    .setMultiChoiceItems(new String[] { "Item1", "Item2" }, null, null)
    .setPositiveButton("确定", null)
    .setNegativeButton("取消", null)
    .show();

new AlertDialog.Builder(this)
  .setTitle("单选框")
  .setIcon(android.R.drawable.ic_dialog_info)
  .setSingleChoiceItems(new String[] { "Item1", "Item2" }, 0,
    new DialogInterface.OnClickListener() {
      public void onClick(DialogInterface dialog, int which) {
      dialog.dismiss();
    }
})
.setNegativeButton("取消", null).show();

new AlertDialog.Builder(this)
    .setTitle("列表框")
    .setItems(new String[] { "Item1", "Item2" }, null)
    .setNegativeButton("确定", null)
    .show();

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:id="@+id/dialog"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:background="#ffffffff"
  android:orientation="horizontal" >
  <TextView
    android:id="@+id/tvname"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="姓名：" />
  <EditText
    android:id="@+id/etname"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:minWidth="100dip" />
</LinearLayout>

LayoutInflater inflater = getLayoutInflater();
View layout = inflater.inflate(R.layout.dialog,(ViewGroup) findViewById(R.id.dialog));
new AlertDialog.Builder(this)
    .setTitle("自定义布局")
    .setView(layout)
    .setPositiveButton("确定", null)
    .setNegativeButton("取消", null)
    .show();

new AlertDialog.Builder(getActivity())
    .setMessage(m)
    .setPositiveButton("确定",
        new DialogInterface.OnClickListener(){
          public void onClick(DialogInterface dialoginterface, int i){}
        })
    .show();