我最近在很多Android应用和游戏中注意到了这种模式：当点击后退按钮时，退出＆＃34;在应用程序中，Toast会出现类似于＆＃34的消息;再次按BACK退出＆＃34;。经过很长一段时间的搜索，我发现一个ANE扩展程序在我的应用程序中显示了一个很好的吐司，我已经测试了它并且单击后退按钮后工作正常，现在我想在单击后退按钮两次后关闭我的应用程序延迟3秒，使用强制代码退出 NativeApplication.nativeApplication.exit（0）;
ANE扩展： https://github.com/mateuszmackowiak/NativeDialogs
我的代码：
import flash.ui.Keyboard;
import flash.events.KeyboardEvent;
import pl.mateuszmackowiak.nativeANE.notifications.Toast;
stop();
NativeApplication.nativeApplication.addEventListener(KeyboardEvent.KEY_DOWN, CheckKeypress);
function CheckKeypress(event: KeyboardEvent): void {
switch (event.keyCode) {
case Keyboard.BACK:
trace("Back key is pressed.");
event.preventDefault();
event.stopImmediatePropagation();
Toast.show("Press Back again to exit", Toast.LENGTH_LONG);
break;
case Keyboard.MENU:
trace("Menu key is pressed.");
break;
case Keyboard.SEARCH:
trace("Search key is pressed.");
break;
}
}
答案 0 :(得分：0)
在MainActivity中尝试此操作。可能有帮助。
import java.io.*;
import java.awt.event.*;
import javax.swing.*;
import java.io.IOException;
import java.nio.file.StandardOpenOption;
public class Editor implements ActionListener
{
boolean updateStatus;
Editor Jedtr;
boolean saved;
boolean newFileFlag;
String fileName;
static File fileRef;
JFrame f;
JMenuBar mb;
JMenu file,edit,help;
JMenuItem cut,copy,paste,selectAll,NewFile,Open,Save,SaveAs;
JTextArea ta;
Editor(){
saved=true;
newFileFlag=true;
fileName=new String("Untitled");
fileRef=new File(fileName);
Open=new JMenuItem("Open File");
Open.addActionListener(this);
file=new JMenu("File");
file.add(Open);
mb=new JMenuBar();
f=new JFrame();
cut=new JMenuItem("Cut");
copy=new JMenuItem("Copy");
paste=new JMenuItem("Paste");
selectAll=new JMenuItem("Select All");
/////////////////////////////////////////////////////////////////////////////////
NewFile =new JMenuItem("New");
Open=new JMenuItem("Open");
Save=new JMenuItem("Save");
SaveAs=new JMenuItem("Save As");
///////////////////////////////////////////////////////////////////////////////////
cut.addActionListener(this);
copy.addActionListener(this);
paste.addActionListener(this);
selectAll.addActionListener(this);
/////////////////////////////////////////////////////////////////////////////////////
NewFile.addActionListener(this);
Open.addActionListener(this);
Save.addActionListener(this);
SaveAs.addActionListener(this);
//////////////////////////////////////////////////////////////////////////////////
mb=new JMenuBar();
file=new JMenu("File");
edit=new JMenu("Edit");
help=new JMenu("Help");
file.add(NewFile);file.add(Open);file.add(Save);file.add(SaveAs);
edit.add(cut);edit.add(copy);edit.add(paste);edit.add(selectAll);
mb.add(file);mb.add(edit);mb.add(help);
///////////////////////////////////////////////////////////////////////////////////////
ta=new JTextArea();
ta.setBounds(5,5,1200,1200);
f.add(mb);f.add(ta);
f.setJMenuBar(mb);
f.setLayout(null);
f.setSize(800,400);
f.setVisible(true);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
/////////////////////////////Action performed/////////////////////////////////////////////////
public void actionPerformed(ActionEvent e)
{
if(e.getSource()==cut)
ta.cut(); // to cut text.
else if(e.getSource()==paste)
ta.paste(); // to paste text.
else if(e.getSource()==copy)
ta.copy(); // to copy text.
else if(e.getSource()==selectAll)
ta.selectAll(); // to select text.
else if(e.getSource()==Open)
{
JFileChooser fc=new JFileChooser();
int i=fc.showOpenDialog(f);
if(i==JFileChooser.APPROVE_OPTION)
{
File f=fc.getSelectedFile();
String filepath=f.getPath();
try
{
BufferedReader br=new BufferedReader(new FileReader(filepath));
String s1="",s2="";
while((s1=br.readLine())!=null)
{
s2+=s1+"\n";
}
ta.setText(s2);
br.close();
}
catch (Exception ex)
{
ex.printStackTrace();
}
}
} //to open an existing file
else if(e.getSource() == NewFile)
{
JFileChooser fc=new JFileChooser();
int j=fc.showOpenDialog(f);
if (j==JFileChooser.CUSTOM_DIALOG);
System.out.println("New File");
File file = new File("C:\\Android\\.txt");
boolean result;
try {
// create a new file
result = file.createNewFile();
// test if successfully created a new file
if(result){
System.out.println("Successfully created "+file.getAbsolutePath());
}
else{
System.out.println("Filed creating "+file.getAbsolutePath());
}
}
catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
} // to create a new file.
else if(e.getSource()== SaveAs)
{ // what to specify here?
}
else if(e.getSource()==Save)
{ // what to specify here?
}
}
/*private Object SaveAs(File temp)
{
// TODO Auto-generated method stub
return null;
}
///////////////////////////////////////////////////////////////////////////////////////////////
private void updateStatus(File temp, boolean b)
{
// TODO Auto-generated method stub
}*/
boolean isSave()
{
return saved;}
void setSave(boolean saved)
{
this.saved=saved;
}
String getFileName()
{
return new String(fileName);
}
void setFileName(String fileName)
{
this.fileName=new String(fileName);
}
////-------File-------////////
//public class File implements ActionListener{}
////-------File-------////////
/*public void actionPerformedf(ActionEvent O) {
if(O.getSource()==Open){
JFileChooser fc=new JFileChooser();
int i=fc.showOpenDialog(f);
if(i==JFileChooser.APPROVE_OPTION){
File f=fc.getSelectedFile();
String filepath=f.getPath();
try{
BufferedReader br=new BufferedReader(new FileReader(filepath));
String s1="",s2="";
while((s1=br.readLine())!=null){
s2+=s1+"\n";
}
ta.setText(s2);
br.close();
}catch (Exception ex)
{
ex.printStackTrace();
}
}
}
}*/
public static void main(String[] args) {
new Editor();
}
}
答案 1 :(得分：0)
您可以在活动中使用onBackPressed（）。当用户按下后退按钮时。将调用此方法。我认为以下代码可以帮助您。
@Override
public void onBackPressed() {
if(initialClickTime == 0){
initialClickTime = System.currentTimeMillis();
//Toast with msg press again to exit
}else{
if ((System.currentTimeMillis() - initialClickTime)/1000 == 3){
finish();
}else{
initialClickTime = 0;
//Toast with msg press again to exit
}
}
答案 2 :(得分：0)
@Override
public void onBackPressed() {
if (doubleBackToExitPressedOnce) {
super.onBackPressed();
return;
}
this.doubleBackToExitPressedOnce = true;
Toast.makeText(this, "Please click BACK again to exit", Toast.LENGTH_SHORT).show();
new Handler().postDelayed(new Runnable() {
@Override
public void run() {
doubleBackToExitPressedOnce=false;
}
}, 2000);
}