将列表视图项目从另一个活动保存回列表视图

Question

我有两个活动：主要和编辑。当我在列表视图中单击一个项目时，它将我带到编辑活动，它在其各自的文本视图中显示项目的详细信息（姓名、姓氏、单元格和电子邮件）。当我单击编辑按钮时，文本视图变得可编辑，当我单击保存按钮时，我需要更新主要活动中的列表视图。请提供代码，因为我还是个初学者。

我的主要课程的代码

public class MainActivity extends AppCompatActivity {

ArrayList<Integer> list = new ArrayList<>();
Button btnAdd = (Button) findViewById(R.id.btnAdd);
ListView lstInfo = (ListView) findViewById(R.id.lstInfo);
Button btnName = (Button) findViewById(R.id.btnName);
Button btnSurname = (Button) findViewById(R.id.btnSurname

);
    Button btnEmail = (Button) findViewById(R.id.btnEmail);
    Button btnDelete = (Button) findViewById(R.id.btnDelete);

    final List<Contact> items = new ArrayList<Contact>();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Toast.makeText(MainActivity.this, "Select a contact to delete", Toast.LENGTH_SHORT).show();
        setContentView(R.layout.activity_main);

        // get views
//        Button btnAdd = (Button) findViewById(R.id.btnAdd);
//        ListView lstInfo = (ListView) findViewById(R.id.lstInfo);
//        Button btnName = (Button) findViewById(R.id.btnName);
//        Button btnSurname = (Button) findViewById(R.id.btnSurname);
//        Button btnEmail = (Button) findViewById(R.id.btnEmail);
//        Button btnDelete = (Button) findViewById(R.id.btnDelete);
//
//        final List<Contact> items = new ArrayList<Contact>();

        //Hard-coding contacts
        items.add(new Contact("Sally", "Van Der Walt", "0766838275", "sally@gmail.com"));
        items.add(new Contact("Sarah", "Smith", "0847852693", "sarah@gmail.com"));
        items.add(new Contact("John", "Doe", "0823691478", "john@gmail.com"));


        // create adapter to transform string items
        final ContactAdapter adapter = new ContactAdapter(this, items);
        //final ContactAdapter conAdapter = new ContactAdapter(this, items);

        // attach adapter to list view
        lstInfo.setAdapter(adapter);

        // add more items when clicked
        btnAdd.setOnClickListener(new View.OnClickListener() {

            public void onClick(View v) {
                adapter.add(new Contact("Name", "Surname", "Cell", "Email"));
                Toast.makeText(MainActivity.this, "New contact has been added", Toast.LENGTH_SHORT).show();
            }
        });

        //Delete the selected user - the selected user will appear in green
        lstInfo.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                if (list.size() >= 1)
                    for (int i = 0; i < list.size(); i++) {
                        if (position == list.get(i))
                            return;
                    }
                Contact cur = items.get(position);
                list.add(position);
                cur.setSelected("(Selected)");
                adapter.notifyDataSetChanged();

            }
        });


        btnDelete.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                for (int i = 0; i < list.size(); i++) {
                    items.remove(list.get(i).intValue());

                }
                adapter.notifyDataSetChanged();
                list.clear();
                Toast.makeText(MainActivity.this, "Contact has been deleted", Toast.LENGTH_SHORT).show();
            }
        });

        //
//        btnDelete.setOnItemClickListener(new Adapter.OnItemClickListener() {
//            @Override public void onItemClick(AdapterView<?> parent, android.view.View view, int position, long id) {
//                list.remove(position);
//            }
//        });


        //
        //Sorting using the adapters sort method
        btnName.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                adapter.sort(new Comparator<Contact>() {
                    @Override
                    public int compare(Contact left, Contact right) {
                        return left.firstName.compareTo(right.firstName);
                    }
                });
            }
        });


        btnSurname.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                adapter.sort(new Comparator<Contact>() {
                    @Override
                    public int compare(Contact left, Contact right) {
                        return left.surname.compareTo(right.surname);
                    }
                });
            }
        });

        btnEmail.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                adapter.sort(new Comparator<Contact>() {
                    @Override
                    public int compare(Contact left, Contact right) {
                        return left.email.compareTo(right.email);
                    }
                });
            }
        });

             lstInfo.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {

                String nameItem = items.get(position).getFirstName();
                String surnameItem = items.get(position).getSurname();
                String cellItem = items.get(position).getCellNumber();
                String emailItem = items.get(position).getEmail();

                Intent intent = new Intent(MainActivity.this, EditingActivity.class);

                intent.putExtra("name", nameItem);
                intent.putExtra("surname", surnameItem);
                intent.putExtra("cell", cellItem);
                intent.putExtra("email", emailItem);

                //startActivity(intent);
                startActivityForResult(intent, 2);
            }
        });
    }

**Code for my editing class:**
    public class EditingActivity extends Activity {

        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            this.setContentView(R.layout.edit_contact);

            Intent intent = getIntent();
            if (intent != null)
            {
                Bundle extras = intent.getExtras();
                if (extras != null)
                {
                    //Get the bundled values
                    String name = extras.getString("name");
                    String surname = extras.getString("surname");
                    String cell = extras.getString("cell");
                    String email = extras.getString("email");

                    //Display the values
                    TextView txtName = (TextView) findViewById(R.id.nameTV);
                    TextView txtSurname = (TextView) findViewById(R.id.surnameTV);
                    TextView txtCell = (TextView) findViewById(R.id.cellTV);
                    TextView txtEmail = (TextView) findViewById(R.id.emailTV);

                    txtName.setText(name);
                    txtSurname.setText(surname);
                    txtCell.setText(cell);
                    txtEmail.setText(email);


                }
            }

            Button editBtn = (Button) findViewById(R.id.editBtn);

            editBtn.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                    TextView txtName = (TextView) findViewById(R.id.nameTV);
                    TextView txtSurname = (TextView) findViewById(R.id.surnameTV);
                    TextView txtCell = (TextView) findViewById(R.id.cellTV);
                    TextView txtEmail = (TextView) findViewById(R.id.emailTV);

                    txtName.setEnabled(true);
                    txtSurname.setEnabled(true);
                    txtCell.setEnabled(true);
                    txtEmail.setEnabled(true);
                }
            });

            Button saveBtn = (Button) findViewById(R.id.saveBtn);

            saveBtn.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {

                }
            });

        }
    }

Answer 1

您可以使用startActivityForResult()查看以下代码以供参考 -

button1.setOnClickListener(new OnClickListener() {  
            @Override  
            public void onClick(View arg0) {  
                Intent intent=new Intent(MainActivity.this,SecondActivity.class);  
                startActivityForResult(intent, 2);// Activity is started with requestCode 2  
            }  
        });  
    }  
 // Call Back method  to get the Message form other Activity  
    @Override  
       protected void onActivityResult(int requestCode, int resultCode, Intent data)  
       {  
                 super.onActivityResult(requestCode, resultCode, data);  
                  // check if the request code is same as what is passed  here it is 2  
                   if(requestCode==2)  
                         {  
                            String message=data.getStringExtra("MESSAGE");   
                            textView1.setText(message);  
                         }  
     }  

onActivityResult 可用于检查已编辑数据的任何更新。

在编辑类中你必须这样做 -

@Override  
    protected void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        setContentView(R.layout.activity_second);  
        editText1=(EditText)findViewById(R.id.editText1);  
            button1=(Button)findViewById(R.id.button1);  
            button1.setOnClickListener(new OnClickListener() {  
                @Override  
                public void onClick(View arg0) {  
                    String message=editText1.getText().toString();  
                    Intent intent=new Intent();  
                    intent.putExtra("MESSAGE",message);  
                    setResult(2,intent);  
                    finish();//finishing activity  
                }  
            });  
    }  

如需进一步了解startActivityForResult()，您可以参考此Java Point Link。

如果您需要更多帮助，请告诉我。

Answer 2

lstInfo.setOnItemClickListener(new AdapterView.OnItemClickListener() { public void onItemClick(AdapterView parent, View view, int position, long id) {

            String nameItem = items.get(position).getFirstName();
            String surnameItem = items.get(position).getSurname();
            String cellItem = items.get(position).getCellNumber();
            String emailItem = items.get(position).getEmail();

            Intent intent = new Intent(MainActivity.this, EditingActivity.class);

            intent.putExtra("name", nameItem);
            intent.putExtra("surname", surnameItem);
            intent.putExtra("cell", cellItem);
            intent.putExtra("email", emailItem);

            startActivity(intent);
        }
    });

首先直接将item对象替换成上面的代码

lstInfo.setOnItemClickListener(new AdapterView.OnItemClickListener() { public void onItemClick(AdapterView parent, View view, int position, long id) {


            Intent intent = new Intent(MainActivity.this, EditingActivity.class);

            intent.putExtra("ItemDetails", items.get(position));

            startActivityForResult(intent,REQUEST_CODE);
        }
    });

访问对象使用

ItemObject details= getIntent().getSerializableExtra("ItemDetails");

在编辑活动中修改保存按钮上的代码

 Button saveBtn = (Button) findViewById(R.id.saveBtn);

        saveBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

             Intent intent=new Intent();
              intent.putExtra("ItemDetail",updateItems);
              setResult(REQUEST_CODE,intent);
            }
        });