如何將選擇的列表項返回給父活動-Android

Question

我正在學習android開發。 我嘗試執行以下操作：

受歡迎的活動，帶有帶有以下文本的TextView：“請選擇”

此Textview設置了OnClick偵聽器。

我的意圖是，當用戶單擊此文本視圖時，必須打開一個具有列表視圖的新活動。

此列表視圖包含一些值，例如：國家1，國家2，國家3等等。

因此，當用戶選擇一個值時，必須將該值返回給父活動。

在我的家長活動中，我有以下內容：

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_login);

    countrySamples = (TextView)findViewById(R.id.countrySamples);
    countrySamples.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            ListCountrySelectedFragment whatKindOjectIsThis = new ListCountrySelectedFragment();
            whatKindOjectIsThis.setListCountrySelectedActivityDelegate(new ListCountrySelectedFragment.ListCountrySelectedActivityDelegate() {
                @Override
                public void selectCountry(String name) {
                    selectItem(name);
                }
            });

        }
    });
}

[...]

    public void selectItem(String name) {
    int index = valuesArray.indexOf(name);
    if (index != -1) {
        countryButton.setText(name);
    }
}

我用列表創建了一個空白片段。

並添加以下代碼：

public static interface ListCountrySelectedActivityDelegate {
    public abstract void selectCountry(String name);
}

private ListCountrySelectedActivityDelegate delegate;

[...]

但是，我的片段永遠不會開始。真實是..我必須為此創建一個片段嗎？ 還是必須通過一項活動？ 還是我完全錯了？

謝謝

編輯（完整代碼）：

登錄活動：

package com.testenum_13;

import android.app.Fragment;
import android.app.FragmentTransaction;
import android.content.Intent;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;

import com.testenum_13.R;
import com.testenum_13.adapters.CountryAdapter;

import org.w3c.dom.Text;

import java.util.ArrayList;
import java.util.HashMap;

public class Login extends ActionBarActivity {

    TextView countryButton;

    private EditText codeField;

    private int countryState = 0;

    private ArrayList<String> countriesArray = new ArrayList<String>();
    private HashMap<String, String> countriesMap = new HashMap<String, String>();

    private boolean ignoreOnTextChange = false;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_login);

        countryButton = (TextView)findViewById(R.id.countryButton);
        countryButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //Intent intent = new Intent(Login.this, CountrySelected.class);
                CountrySelected fragment = new CountrySelected();
                fragment.setCountrySelectActivityDelegate (new CountrySelected.CountrySelectActivityDelegate() {
                    @Override
                    public void countryWSelected(String name) {
                        selectCountry(name);
                    }
                });
                //startActivity(intent);
            }
        });
    }

    @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_login, 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 selectCountry(String name) {
        int index = countriesArray.indexOf(name);
        if (index != -1) {
            ignoreOnTextChange = true;
            codeField.setText(countriesMap.get(name));
            countryButton.setText(name);
            countryState = 0;
        }
    }
}

國家活動：

package com.testenum_13;

import android.content.Context;
import android.support.v4.app.FragmentActivity;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.support.v7.internal.widget.ActionBarOverlayLayout;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ListView;
import android.widget.TextView;

import com.testenum_13.adapters.CountryAdapter;
import com.testenum_13.adapters.CountryAdapter.Country;

import java.util.List;


public class CountrySelected extends FragmentActivity {
    public static interface CountrySelectActivityDelegate {
        public abstract void countryWSelected(String name);
    }
    private CountryAdapter listViewAdapter;
    private CountrySelectActivityDelegate delegate;

    ListView countryList;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_country_selected);

        countryList = (ListView)findViewById(R.id.countryList);

        listViewAdapter = new CountryAdapter(getBaseContext());

        countryList.setAdapter(listViewAdapter);
        countryList.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                Country country = null;

                int section = listViewAdapter.getSectionForPosition(position);
                int row = listViewAdapter.getPositionInSectionForPosition(position);
                if (row < 0 || section < 0) {
                    return;
                }
                country = listViewAdapter.getItem(section, row);
                if (position < 0) {
                    return;
                }
                if (country != null && delegate != null)
                {
                    delegate.countryWSelected(country.name);
                }
                finish();
            }
        });

    }

    public void setCountrySelectActivityDelegate(CountrySelectActivityDelegate delegate) {
        this.delegate = delegate;
    }

    @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_country_selected, 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);
    }
}

謝謝

Answer 1

您可以在父活動中使用startActivityForResult(Intent, int) ，並在子活動中覆蓋onActivityResult() 。 有關如何實施此模式的更多詳細信息，請參見本教程。