Question

当我继续执行其子活动后返回MainActivity时，我正在尝试在MainActivity中保留EditText的内容。在MainActivity中，我有两个EditText字段，一个存储名字其他商店的姓氏和按钮，点击时调用newActivity（）方法。然后在作为MainActivity的Child的SecondActivity中显示第一个和最后一个名称，但是当我对MainActivity进行bact时，EditText字段的内容不会被保留。

以下是我在MainActivity.java和SecondActivity.java中编写的代码

    /************ MainActivity.java *************/

        public class MainActivity extends ActionBarActivity {

        private EditText firstNameField ;
        private EditText lastNameField ;
        private String firstName, lastName;

        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            firstNameField = (EditText) findViewById(R.id.firstNameField);
            lastNameField = (EditText) findViewById(R.id.lastNameField);
        }

        @Override
        public boolean onCreateOptionsMenu(Menu menu) {
            // Inflate the menu; this adds items to the action bar if it is present.
            getMenuInflater().inflate(R.menu.menu_main, menu);
            return true;
        }

        @Override
        public boolean onOptionsItemSelected(MenuItem item) {
            // Handle action bar item clicks here. The action bar will
            // automatically handle clicks on the Home/Up button, so long
            // as you specify a parent activity in AndroidManifest.xml.
            int id = item.getItemId();

            //noinspection SimplifiableIfStatement
            if (id == R.id.action_settings) {
                return true;
            }

            return super.onOptionsItemSelected(item);
        }


        public void newActivity(View view) {

            firstName = String.valueOf(firstNameField.getText());
            lastName = String.valueOf(lastNameField.getText());

            Intent secondActivity = new Intent(this, SecondActivity.class);
            secondActivity.putExtra("First name", firstName);
            secondActivity.putExtra("Last Name", lastName);
            secondActivity.putExtra("Last name", lastName);

            startActivity(secondActivity);


        }

        @Override
        public void onSaveInstanceState(Bundle outState, PersistableBundle outPersistentState) {
            outState.putString(FIRST_NAME_KEY, firstName);
            outState.putString(LAST_NAME_KEY, lastName);
            super.onSaveInstanceState(outState, outPersistentState);
        }

        public void onRestoreInstanceState(Bundle savedInstanceState) {
            // Always call the superclass so it can restore the view hierarchy
            super.onRestoreInstanceState(savedInstanceState);

            // Restore state members from saved instance
            firstName = String.valueOf(savedInstanceState.getString(FIRST_NAME_KEY));
            lastName = String.valueOf(savedInstanceState.getString(LAST_NAME_KEY));
            firstNameField.setText(""+firstName);
            lastNameField.setText(""+lastName);
        }
    }

/************** SecondActivity.java ***********/

public class SecondActivity extends ActionBarActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.second_activity);

        String fname = String.valueOf(getIntent().getStringExtra("First name"));
        String lname = String.valueOf(getIntent().getStringExtra("Last name"));

        EditText firstNameEdt = (EditText) findViewById(R.id.firstNameEdt);
        EditText lastNameEdt = (EditText) findViewById(R.id.lastNameEdt);

        firstNameEdt.setText(""+ fname);
        lastNameEdt.setText("" + lname);
    }
}

Answer 1

您可以在SharedPreferences中保存edittexts的值。在那里，您可以使用已定义的密钥保存持久值。

您希望保存MainActivity onDestroy中的值，并在onCreate中检索您的值。

在这里，您可以阅读如何使用SharedPreferences：Saving Key-Value Sets

Answer 2

大多数UI小部件负责在活动实例之间传播自己的状态。如果您注释掉onSaveInstanceState和onRestoreInstanceState方法，它可能会起作用。如果您的活动具有与UI分开的自己的状态，则只需要实现这些方法。

Answer 3

对于一个简单的方法，如果您可以将内容带到第二个活动，为什么不在回到第一个活动时做同样的事情。使用bundle返回第1个活动，然后将其设置为Text

当我继续进行子活动并返回MainActivity时，如何在MainActivity中保留EditText的内容？

3 个答案: