listView动态添加项目

Question

我曾经ListView动态添加项目,但有一个问题是没有平滑添加.我的listActivity中有textView和按钮,Iwant to Press按钮,然后TextView的文字可以自动添加ListView,但我按下按钮,它不工作,除非我输入内容后,按"确定"键,然后按下按钮,TextView's文字即可自动添加到ListView.我不知道为什么.如果我连续按下按钮,为3次,则按"确定"键,内容

自动添加列表

查看3次.

 public class DynamicListItems extends ListActivity {
   private static final String   ITEM_KEY   = "key";
   ArrayList<HashMap<String, String>>   list= new ArrayList<HashMap<String, String>>();
private SimpleAdapter   adapter;
private EditText    newValue;@Override
public void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);
    setContentView(R.layout.dynamic_list);
    newValue = (EditText) findViewById(R.id.new_value_field);

    setListAdapter(new SimpleAdapter(this, list, R.layout.row, new String[] { ITEM_KEY }, new int[] { R.id.list_value }));
    ((ImageButton) findViewById(R.id.button)).setOnClickListener(getBtnClickListener());
}

private OnClickListener getBtnClickListener() {
    return new OnClickListener() {
        public void onClick(View view) {
            try {

                HashMap<String, String> item = new HashMap<String, String>();
                item.put(ITEM_KEY, newValue.getText().toString());
                list.add(item);

                adapter.notifyDataSetChanged();
            } catch (NullPointerException e) {
                Log.i("[Dynamic Items]", "Tried to add null value");
            }
        }
    };
   }}

如何动态删除项目？

• dynamic_list.xml只包含listView,button,textView
• row.xml包含 TextView

Answer 1

notifyDataSetChanged()方法用于更新适配器.

在这里,我将逐步发布一个有效的答案.

首先main.xml中的文件:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true" 
        android:id="@+id/input">

        <EditText
            android:id="@+id/editText_input"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:ems="10" >

            <requestFocus />
        </EditText>

        <Button
            android:id="@+id/button_add"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="0"
            android:text="Add" />
    </LinearLayout>


    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_above="@+id/input"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:orientation="vertical" >

        <ListView
            android:id="@+id/listView_items"
            android:layout_width="match_parent"
            android:layout_height="wrap_content" >
        </ListView>

    </LinearLayout>

</RelativeLayout>

这里是MainActivity.java:

import java.util.ArrayList;

import android.app.Activity;
import android.os.Bundle;
import android.view.KeyEvent;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;

public class MainActivity extends Activity {
    private EditText etInput;
    private Button btnAdd;
    private ListView lvItem;
    private ArrayList<String> itemArrey;
    private ArrayAdapter<String> itemAdapter;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.dyanamic_list);
        setUpView();

    }

    private void setUpView() {
        etInput = (EditText)this.findViewById(R.id.editText_input);
        btnAdd = (Button)this.findViewById(R.id.button_add);
        lvItem = (ListView)this.findViewById(R.id.listView_items);

        itemArrey = new ArrayList<String>();
        itemArrey.clear();

        itemAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1,itemArrey);
        lvItem.setAdapter(itemAdapter);

        btnAdd.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                addItemList();
            }
        });

        etInput.setOnKeyListener(new View.OnKeyListener() {
            public boolean onKey(View v, int keyCode, KeyEvent event) {
                if (keyCode == KeyEvent.KEYCODE_ENTER) {
                    addItemList();
                }
                return true;
            }
        });
    }

    protected void addItemList() {
        if (isInputValid(etInput)) {
            itemArrey.add(0,etInput.getText().toString());
            etInput.setText("");
            itemAdapter.notifyDataSetChanged();
        }   
    }

    protected boolean isInputValid(EditText etInput2) {
        if (etInput2.getText().toString().trim().length()<1) {
            etInput2.setError("Please Enter Item");
            return false;
        } else {
            return true;
        }
    }
}