主activity按返回键弹出确认退出对话框

public boolean onKeyDown(int keyCode, KeyEvent event) {

// 按下键盘上返回按钮

if (keyCode == KeyEvent.KEYCODE_BACK) {

new AlertDialog.Builder(this)

.setTitle("提示")

.setMessage("你确定退出吗？")

.setNegativeButton("取消",

new DialogInterface.OnClickListener() {

public void onClick(DialogInterface dialog, int which) {

// TODO Auto-generated method stub

}

})

.setPositiveButton("确定",

new DialogInterface.OnClickListener() {

public void onClick(DialogInterface dialog, int whichButton) {

finish();

}

}).show();

return true;

} else {

return super.onKeyDown(keyCode, event);

}

}