向 android 中的后退键添加功能以转到文件管理器中的上一个文件夹位置
adding functionality to back key in android to go to previous folder location in a file manager
我知道这个问题已经讨论了很多次,但我真的想不通。很抱歉又问了一遍。我正在制作 android 文件管理器。我在列表视图中显示文件和文件夹。我想向 "back" 键添加功能。当前随时按返回键都会退出应用程序。我希望它转到上一个文件夹(如果有)或以其他方式退出应用程序。我正在尝试 onBackPressed()
方法,但无法弄清楚应该在那里写什么。请帮我。
这是我的 MainActivity.java 文件:
public class MainActivity extends ListActivity {
private ArrayList<String> item = null;
private ArrayList<String> path = null;
private String root="/";
private TextView myPath;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState); /**super keyword in java is a reference variable that
is used to refer immediate parent class object. */
setContentView(R.layout.activity_main);
myPath = (TextView)findViewById(R.id.path); /* storing the current path*/
getDir(root);
}
private void getDir(String dirPath)
{
myPath.setText("Location: " + dirPath);
item = new ArrayList<String>();
path = new ArrayList<String>();
File f = new File(dirPath);
File[] files = f.listFiles(); /** files is an array of all the files in a directory. */
if(!dirPath.equals(root))
{
item.add(root);
path.add(root);
item.add("../");
path.add(f.getParent());
}
for(int i=0; i < files.length; i++)
{
File file = files[i];
path.add(file.getPath());
if(file.isDirectory())
item.add(file.getName() + "/");
else
item.add(file.getName());
}
ArrayAdapter<String> fileList = new ArrayAdapter<String>(this, R.layout.row, item);
setListAdapter(fileList);
}
protected void onListItemClick(ListView l, View v, int position, long id) {
File file = new File(path.get(position));
if (file.isDirectory())
{
if(file.canRead())
getDir(path.get(position));
else
{
new AlertDialog.Builder(this)
.setIcon(R.drawable.icon)
.setTitle("[" + file.getName() + "] folder can't be read!")
.setPositiveButton("OK",
new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
// TODO Auto-generated method stub
}
}).show();
}
}
else
{
new AlertDialog.Builder(this)
.setIcon(R.drawable.icon)
.setTitle("[" + file.getName() + "]")
.setPositiveButton("OK",
new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
// TODO Auto-generated method stub
}
}).show();
}
}
你可以试试这个:
@Override
protected void onBackPressed(){
//super.onBackPressed(); //remove it if you want control
String previousDir = "build your previous dir here";
if (previousDir != null){ //if deferent root path
Intent activityDir = new Intent(this, MainActivity.class);
activityDir.putExtra("DIR_PATH", previousDir);
startActivity(activityDir);
}//end if
finish(); //close this screen to show new screen above with new path
}
注意:您必须按以下代码编辑 onCreate(....):
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState); /**super keyword in java is a reference variable that
is used to refer immediate parent class object. */
setContentView(R.layout.activity_main);
myPath = (TextView)findViewById(R.id.path); /* storing the current path*/
if(getIntent() != null){
root = getIntent().getStringExtra("DIR_PATH", root); //if is null then get root
}
getDir(root);
}
我知道这个问题已经讨论了很多次,但我真的想不通。很抱歉又问了一遍。我正在制作 android 文件管理器。我在列表视图中显示文件和文件夹。我想向 "back" 键添加功能。当前随时按返回键都会退出应用程序。我希望它转到上一个文件夹(如果有)或以其他方式退出应用程序。我正在尝试 onBackPressed()
方法,但无法弄清楚应该在那里写什么。请帮我。
这是我的 MainActivity.java 文件:
public class MainActivity extends ListActivity {
private ArrayList<String> item = null;
private ArrayList<String> path = null;
private String root="/";
private TextView myPath;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState); /**super keyword in java is a reference variable that
is used to refer immediate parent class object. */
setContentView(R.layout.activity_main);
myPath = (TextView)findViewById(R.id.path); /* storing the current path*/
getDir(root);
}
private void getDir(String dirPath)
{
myPath.setText("Location: " + dirPath);
item = new ArrayList<String>();
path = new ArrayList<String>();
File f = new File(dirPath);
File[] files = f.listFiles(); /** files is an array of all the files in a directory. */
if(!dirPath.equals(root))
{
item.add(root);
path.add(root);
item.add("../");
path.add(f.getParent());
}
for(int i=0; i < files.length; i++)
{
File file = files[i];
path.add(file.getPath());
if(file.isDirectory())
item.add(file.getName() + "/");
else
item.add(file.getName());
}
ArrayAdapter<String> fileList = new ArrayAdapter<String>(this, R.layout.row, item);
setListAdapter(fileList);
}
protected void onListItemClick(ListView l, View v, int position, long id) {
File file = new File(path.get(position));
if (file.isDirectory())
{
if(file.canRead())
getDir(path.get(position));
else
{
new AlertDialog.Builder(this)
.setIcon(R.drawable.icon)
.setTitle("[" + file.getName() + "] folder can't be read!")
.setPositiveButton("OK",
new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
// TODO Auto-generated method stub
}
}).show();
}
}
else
{
new AlertDialog.Builder(this)
.setIcon(R.drawable.icon)
.setTitle("[" + file.getName() + "]")
.setPositiveButton("OK",
new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
// TODO Auto-generated method stub
}
}).show();
}
}
你可以试试这个:
@Override
protected void onBackPressed(){
//super.onBackPressed(); //remove it if you want control
String previousDir = "build your previous dir here";
if (previousDir != null){ //if deferent root path
Intent activityDir = new Intent(this, MainActivity.class);
activityDir.putExtra("DIR_PATH", previousDir);
startActivity(activityDir);
}//end if
finish(); //close this screen to show new screen above with new path
}
注意:您必须按以下代码编辑 onCreate(....):
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState); /**super keyword in java is a reference variable that
is used to refer immediate parent class object. */
setContentView(R.layout.activity_main);
myPath = (TextView)findViewById(R.id.path); /* storing the current path*/
if(getIntent() != null){
root = getIntent().getStringExtra("DIR_PATH", root); //if is null then get root
}
getDir(root);
}