java - 在 Android 中通过 Intent 传递信息后将项目添加到 listView

Question

我正在尝试添加一个项目，首先使用添加按钮，然后转到不同的 Activity ，然后返回原始 Activity 并将其添加到 ListView 中。我似乎不能拥有超过一件元素。

AddScreen.class(我的第一个 Activity ):

    package com.painLogger;
    **IMPORTS**
    public class AddScreen extends Activity implements OnClickListener,
    OnItemClickListener {
/** Called when the activity is first created. */
Button addButton;
SimpleAdapter adapter;
List<HashMap<String, String>> painItems = new ArrayList<HashMap<String, String>>();
ListView listthings;
int[] to;
String[] from;
String painLevelString, timeOfPainString, textTreatmentString,
        painLocation, row1, row2;
TextView painTitle;
boolean myFirstTime;
int k;


@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.addscreen);
    // if it's the first time opening the app, then go to 'AddMyInfo.class'
    SharedPreferences settings = this.getSharedPreferences("MyApp", 0);
    SharedPreferences.Editor e = settings.edit();
    boolean firstrun = settings.getBoolean("firstrun", true);
    if (firstrun) {
        e.putBoolean("firstrun", false);
        e.commit();
        Intent intent = new Intent(this, AddMyInfo.class);
        startActivity(intent);
    }
    //initialize painTitle and set its font
    painTitle = (TextView) findViewById(R.id.painTitle);
    Typeface font = Typeface.createFromAsset(getAssets(),
            "Chantelli_Antiqua.ttf");
    painTitle.setTypeface(font);
    listthings = (ListView) findViewById(R.id.listthings);
    from = new String[] { "row_1" + painItems.size(),
            "row_2" + painItems.size() };
    to = new int[] { R.id.row1, R.id.row2 };
    adapter = new SimpleAdapter(this, painItems, R.layout.mylistlayout,
            from, to);
    listthings.setAdapter(adapter);
    listthings.setOnItemClickListener(this);
    addButton = (Button) findViewById(R.id.addButton);
    addButton.setOnClickListener(this);

}

@Override
//on the activityresult,get the string extra, then add the item to the list
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
     if(this.getIntent().hasExtra("row1")){
     row1 = this.getIntent().getStringExtra("row1");
     row2 = this.getIntent().getStringExtra("row2");
     painLevelString = 
             this.getIntent().getStringExtra("com.painLogger.painLevel");
     painLocation = this.getIntent().getStringExtra("painLocation");
     timeOfPainString = 
             this.getIntent().getStringExtra("com.painLogger.painTime");
     textTreatmentString = 
             this.getIntent().getStringExtra("com.painLogger.treatment");
     addItem();
    }
}
 // to add the item, put it in the map, and add the map into the list
private void addItem() {
    HashMap<String, String> map = new HashMap<String, String>();
    map.put("row_1" + painItems.size(), row1);
    map.put("row_2" + painItems.size(), row2);
    painItems.add(map);
    adapter.notifyDataSetChanged();

}

public void onClick(View v) {
    // When '+' clicked, go to the PainLoggerActivity.java, where you can
    // click enter, and that sends those strings back to here, where I can
    // incorporate them into a list view, same as was there in the
    // PainLogger Activity

    Intent goToFields = new Intent (this, PainLoggerActivity.class);
    //put the desired extras into the intent
    startActivityForResult(goToFields, 1);


}

public void onItemClick(AdapterView<?> a, View v, int position, long id) {
    Intent intent = new Intent(this, Item1.class);
    intent.putExtra("com.painLogger.painLevel", painLevelString);
    intent.putExtra("com.painLogger.painTime", timeOfPainString);
    intent.putExtra("com.painLogger.treatment", textTreatmentString);
    intent.putExtra("painLocation", painLocation);
    startActivity(intent);
}

}  

我的 PainLoggerActivity，我在其中输入要放入列表中的各种信息:

包 com.painLogger; //导入 公共(public)类 PainLoggerActivity 扩展 Activity 实现 OnClickListener， OnItemClickListener, OnKeyListener {

/** Called when the activity is first created. */
EditText txtItem, txtItem2, timeOfPain, textTreatment, painLevel;

Button btnAdd;
ListView listItems;
ArrayAdapter<String> aa;
List<HashMap<String, String>> painItems = new ArrayList<HashMap<String, String>>();
int[] to;
String[] from;
SimpleAdapter adapter;
String timeOfPainString, textTreatmentString, painLevelString, painLocation;
Spinner s;
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    txtItem = (EditText) findViewById(R.id.txtItem);
    txtItem2 = (EditText) findViewById(R.id.txtItem2);
    timeOfPain = (EditText)findViewById(R.id.timeOfPain);
    textTreatment = (EditText)findViewById(R.id.textTreatment);
    painLevel = (EditText)findViewById(R.id.painLevel);

    btnAdd = (Button) findViewById(R.id.btnAdd);
    listItems = (ListView) findViewById(R.id.listItems);

    btnAdd.setOnClickListener(this);

    from = new String[] { "row_1", "row_2" };
    to = new int[] { R.id.row1, R.id.row2 };

    adapter = new SimpleAdapter(this, painItems,
            R.layout.mylistlayout, from, to);
    listItems.setAdapter(adapter);

    listItems.setOnItemClickListener(this);
    s = (Spinner) findViewById(R.id.spinner1);      
    ArrayAdapter<?>adapter = ArrayAdapter.createFromResource(
            this, R.array.planets, android.R.layout.simple_spinner_item);
    adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    s.setAdapter(adapter);



}

private void addItem() {
    timeOfPainString = timeOfPain.getText().toString();
    textTreatmentString = textTreatment.getText().toString();
    painLevelString = s.getSelectedItem().toString();
    painLocation = txtItem.getText().toString();
    Intent intent = new Intent (this, AddScreen.class);
    intent.putExtra("com.painLogger.painLevel", painLevelString);
    intent.putExtra("com.painLogger.painTime", timeOfPainString);
    intent.putExtra("com.painLogger.treatment", textTreatmentString);
    intent.putExtra("painLocation", painLocation);
    setResult(1, intent);
    finish();

    HashMap<String, String> map = new HashMap<String, String>();
    map.put("row_1", txtItem.getText().toString());
    map.put("row_2", txtItem2.getText().toString());
    painItems.add(map);
    adapter.notifyDataSetChanged();


    }


public void onClick(View v) {
    if (v == this.btnAdd) {
        addItem();

    }

}

public boolean onKey(View v, int keyCode, KeyEvent event) {

    if (event.getAction() == KeyEvent.ACTION_DOWN
            && keyCode == KeyEvent.KEYCODE_DPAD_CENTER) {
        this.addItem();

    }
    return false;

}

public void onItemClick(AdapterView<?> a, View v, int position, long id) {

        timeOfPainString = timeOfPain.getText().toString();
        textTreatmentString = textTreatment.getText().toString();
        painLevelString = s.getSelectedItem().toString();
        painLocation = txtItem.getText().toString();
        //create the intent
        Intent intent = new Intent (this, Item1.class);
        //put the desired extras into the intent
        intent.putExtra("com.painLogger.painLevel", painLevelString);
        intent.putExtra("com.painLogger.painTime", timeOfPainString);
        intent.putExtra("com.painLogger.treatment", textTreatmentString);
        intent.putExtra("pain location", painLocation);


        startActivity(intent);
        //set the variables to "", empty

}

}

My Item1.class 只是单击列表中的项目时应用程序所在的位置。它没有其他目的。

我遇到问题，因为当我在列表中添加该项目时，它会替换前一个项目，而我只剩下一项。

Answer 1

这是一个经过测试的原型(prototype):

TestResultActivity.java

package com.arrdude.forumanswer;

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

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;

public class TestResultActivity extends Activity implements OnClickListener {
    private static final int REQUEST_LIST_ITEM = 235; //arbitrary request code
    static final String ADAPTER_VALUE_1 = "head";
    static final String ADAPTER_VALUE_2 = "sub";

    ArrayList<HashMap<String, String>> masterlist = null;
    ListAdapter adapter = null;

    ListView listview = null;
    Button addbutton = null;

    public ListAdapter getAdapter() {
        if(adapter == null){
            adapter = new SimpleAdapter(this, getMylist(), R.layout.listitem, new String[] {ADAPTER_VALUE_1, ADAPTER_VALUE_2}, new int[] {R.id.listheading, R.id.listsubheading});
        }
        return adapter;
    }

    public ListView getListview() {
        if(listview==null){
            listview = (ListView) findViewById(R.id.mainlistview);
            listview.setAdapter(getAdapter());
        }
        return listview;
    }

    public Button getAddbutton() {
        if(addbutton==null){
            addbutton = (Button) findViewById(R.id.mainaddbutton);
            addbutton.setClickable(true);
            addbutton.setOnClickListener(this);
        }
        return addbutton;
    }

    public ArrayList<HashMap<String, String>> getMylist() {
        if(masterlist==null){
            masterlist = new ArrayList<HashMap<String,String>>();
        }
        return masterlist;
    }

    public void addListItem(String head, String sub){
        HashMap<String, String> addme=new HashMap<String, String>();
        addme.put(ADAPTER_VALUE_1, head);
        addme.put(ADAPTER_VALUE_2, sub);

        masterlist.add(addme);
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        //lazy init objects not the most efficient in Android but easier reading
        getListview();
        getAddbutton();
        addListItem("Test Head", "Test sub heading here below"); //an initial item for testing
    }

    @Override
    public void onClick(View v) {
        Intent launchadditemI = new Intent(this, AddItemActivity.class);
        startActivityForResult(launchadditemI, REQUEST_LIST_ITEM);
    }

    @Override
    public void onActivityResult(int req, int res, Intent data){
        if(req == REQUEST_LIST_ITEM && res == RESULT_OK){
            String thishead = data.getStringExtra(ADAPTER_VALUE_1);
            String thissub = data.getStringExtra(ADAPTER_VALUE_2);
            addListItem(thishead, thissub);
        }
    }
}

AddItemActivity.java

package com.arrdude.forumanswer;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;

public class AddItemActivity extends Activity implements OnClickListener {
    EditText headeredittext = null;
    EditText subheadedittext = null;
    Button donebutton = null;
    Button cancelbutton = null;

    public EditText getHeaderedittext() {
        if(headeredittext==null){
            headeredittext = (EditText) findViewById(R.id.headedittext);
        }
        return headeredittext;
    }

    public EditText getSubheadedittext() {
        if(subheadedittext==null){
            subheadedittext = (EditText) findViewById(R.id.subedittext);
        }
        return subheadedittext;
    }

    public Button getDonebutton() {
        if(donebutton==null){
            donebutton = (Button) findViewById(R.id.adddonebutton);
            donebutton.setClickable(true);
            donebutton.setOnClickListener(this);
        }
        return donebutton;
    }

    public Button getCancelbutton() {
        if(cancelbutton==null){
            cancelbutton = (Button) findViewById(R.id.addcancelbutton);
            cancelbutton.setOnClickListener(this);
        }
        return cancelbutton;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.additem);
        //lazy init objects not the most efficient in Android but easier reading
        getHeaderedittext();
        getSubheadedittext();
        getDonebutton();
        getCancelbutton();
    }

    @Override
    public void onClick(View arg0) {
        switch (arg0.getId()) {
        case R.id.addcancelbutton:
            finish();
            break;

        case R.id.adddonebutton:
            sendResult();
            break;

        default:
            break;
        }
    }

    private void sendResult() {
        Intent resultI = new Intent();
        resultI.putExtra(TestResultActivity.ADAPTER_VALUE_1, getHeaderedittext().getText().toString());
        resultI.putExtra(TestResultActivity.ADAPTER_VALUE_2, getSubheadedittext().getText().toString());
        setResult(RESULT_OK, resultI);
        finish();
    }
}

main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
<TextView  
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" android:text="@string/maintitle"/>
<ListView android:layout_height="wrap_content" android:layout_width="fill_parent" android:id="@+id/mainlistview"></ListView>
<Button android:id="@+id/mainaddbutton" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="@string/addbuttontext"></Button>
</LinearLayout>

additem.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:orientation="vertical"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent">
    <LinearLayout android:layout_height="wrap_content" android:layout_width="fill_parent" android:id="@+id/LinearLayout01">
        <TextView android:layout_width="wrap_content" android:text="Header:" android:layout_height="wrap_content" android:id="@+id/TextView01"></TextView>
        <EditText android:layout_weight="1" android:layout_width="fill_parent" android:id="@+id/headedittext" android:layout_height="wrap_content">
            <requestFocus></requestFocus>
        </EditText>
    </LinearLayout>
    <LinearLayout android:layout_height="wrap_content" android:layout_width="fill_parent" android:id="@+id/linearLayout2">
        <TextView android:text="Subhead:" android:id="@+id/textView1" android:layout_width="wrap_content" android:layout_height="wrap_content"></TextView>
        <EditText android:layout_weight="1" android:layout_width="fill_parent" android:id="@+id/subedittext" android:layout_height="wrap_content"></EditText>
    </LinearLayout>
    <LinearLayout android:layout_height="wrap_content" android:layout_width="fill_parent" android:id="@+id/linearLayout1">
        <Button android:text="Cancel" android:id="@+id/addcancelbutton" android:layout_width="wrap_content" android:layout_height="wrap_content"></Button>
        <Button android:text="Add Item" android:id="@+id/adddonebutton" android:layout_width="wrap_content" android:layout_height="wrap_content"></Button>
    </LinearLayout>

</LinearLayout>

listitem.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="fill_parent"
    android:layout_height="fill_parent">
    <TextView android:id="@+id/listheading" android:layout_width="wrap_content"
        android:layout_height="26dip" android:layout_alignParentTop="true"
        android:textSize="20sp" />
    <TextView android:id="@+id/listsubheading"
        android:layout_width="wrap_content" android:layout_height="22dip"
        android:layout_below="@id/listheading" android:textSize="16sp" />
</RelativeLayout>

字符串.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <string name="maintitle">List Items:</string>
    <string name="app_name">TestResultActivity</string>
    <string name="addbuttontext">Add New Item</string>
</resources>

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="com.arrdude.forumanswer"
      android:versionCode="1"
      android:versionName="1.0">
    <uses-sdk android:minSdkVersion="4" />

    <application android:icon="@drawable/icon" android:label="@string/app_name">
        <activity android:name=".TestResultActivity"
                  android:label="@string/app_name">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity android:name=".AddItemActivity"></activity>

    </application>
</manifest>

祝你编码愉快!