Android应用程序开发中的条件弹出消息

Question

首先，我对Android Studio和Android应用程序开发非常陌生。我想在我的应用程序中显示一个有条件的弹出窗口，只有当条件不满足时，弹出窗口才会出现。

Double billAmount = new Double(etBillAmount.getText().toString());
Double TipPercentage = new Double(etTipPercentage.getText().toString());
// The popup should be given when the Tip percentage is greater than 100 or else continue with 
the code
if (TipPercentage > 100)
{
System.out.println("Please enter Tip Percentage between 0 to 100. Thank you");
System.exit(0);
}
Double totalBill;
Double totalTip;
totalTip = TipPercentage*billAmount/100;
totalBill = totalTip + billAmount;
tvTotal.setText("$ " + totalTip.toString());   
tvTip.setText("$ " + totalBill.toString());

这是代码，当if语句中的条件不满足时，我想弹出一条消息。如果可能的话，请帮我把它弄清楚。

请帮我提前感谢大家：(：(：！！！！！！！！！！！

Answer 1

对于弹出消息，您可以使用Toast

Toast.makeText(this, "Please enter Tip Percentage between 0 to 100. Thank you", Toast.LENGTH_SHORT).show();

所以你需要在if块中添加toast，而不是system.out.println

if (TipPercentage > 100){
Toast.makeText(this, "Please enter Tip Percentage between 0 to 100. Thank you", Toast.LENGTH_SHORT).show();
}

或者你也可以使用警报对话。对于警报对话，请点击此链接https://developer.android.com/guide/topics/ui/dialogs

Answer 2

the code
if (TipPercentage > 100){
System.out.println("Please enter Tip Percentage between 0 to 100. Thank you");
System.exit(0);}else{
dialogOpenTop(NotificationDialogActivity.this,"pass string");
}}
public void dialogOpenTop(final Context context, String toke) {
final Dialog dialog = new Dialog(NotificationDialogActivity.this);           dialog.setContentView(R.layout.alert);
dialog.getWindow().setBackgroundDrawable(new ColorDrawable(Color.TRANSPARENT));
dialog.setCancelable(false);
dialog.setTitle("Demo for bottom dialog");
LinearLayout someLayout = dialog.findViewById(R.id.someLayout);
Button btnOk = dialog.findViewById(R.id.btnOk);
}
layout
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/scrollViewLuogo"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:descendantFocusability="beforeDescendants"
android:focusableInTouchMode="true"
android:fitsSystemWindows="false"
>
<LinearLayout
android:focusableInTouchMode="true"
android:padding="@dimen/margin_10dp"
android:id="@+id/someLayout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:background="@drawable/dialog_background"
android:orientation="vertical">
<TextView
android:padding="@dimen/margin_10dp"
android:textStyle="bold"
android:id="@+id/title_message"
android:layout_gravity="center"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Your message"
android:layout_marginBottom="4dp"
android:textSize="18sp" />
<ScrollView android:id="@+id/scroll_view"
android:layout_width="match_parent"
android:fitsSystemWindows="true"
android:fadeScrollbars="false"
style="@style/scroll_style"
android:layout_height="match_parent"
tools:ignore="UselessParent">
<LinearLayout android:id="@+id/scroll_layout"
android:padding="@dimen/margin_10dp"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical" >


<ImageView
android:layout_below="@+id/title_message"
android:adjustViewBounds="true"
android:id="@+id/btnAlert"
android:layout_gravity="center"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:visibility="visible" />

<TextView
android:paddingTop="@dimen/margin_10dp"
android:paddingBottom="@dimen/margin_10dp"
android:layout_below="@+id/btnAlert"
android:layout_gravity="center"
android:id="@+id/text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="YOur message"
android:textSize="18sp" />
<Button
android:id="@+id/btnOk"
android:minWidth="@dimen/margin_0dp"
android:minHeight="@dimen/margin_0dp"
android:textSize="@dimen/text_20sp"
android:paddingTop="2dp"
android:paddingBottom="2dp"
android:paddingLeft="@dimen/margin_height_50dp"
android:paddingRight="@dimen/margin_height_50dp"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_marginTop="2dp"
android:background="@drawable/dialog_button"
android:focusable="true"
android:focusedByDefault="true"
android:text="Ok" />
<Button
android:visibility="gone"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Next actvity"
android:id="@+id/nxt"/>
</LinearLayout>
</ScrollView>
</LinearLayout>
</LinearLayout>