Question

我正在做一个Android搜索功能实验室。它有一些我不明白的错误。错误发生在

lv = (ListView) findViewById(R.id.list_view);
inputSearch = (EditText) findViewById(R.id.inputSearch); and
adapter = new ArrayAdapter<String>(this, R.layout.activity_list_item,
                R.id.product_name, products);

谁能告诉我wt是问题？谢谢！

package com.example.s.o.m.e;

import java.util.ArrayList;
import java.util.HashMap;
import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.text.Editable;
import android.text.TextWatcher;
import android.view.MotionEvent;
import android.view.inputmethod.InputMethodManager;
import android.widget.ArrayAdapter;
import android.widget.EditText;
import android.widget.ListView;

public class Video extends Fragment {

    // List view
    private ListView lv;

    // Listview Adapter
    ArrayAdapter<String> adapter;

    // Search EditText
    EditText inputSearch;

    // ArrayList for Listview
    ArrayList<HashMap<String, String>> productList;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_video);

        // Listview Data
        String products[] = { "DEF", "POA",
                "ABC", "BCD" };

        lv = (ListView) findViewById(R.id.list_view);
        inputSearch = (EditText) findViewById(R.id.inputSearch);

        // Adding items to listview
        adapter = new ArrayAdapter<String>(this, R.layout.activity_list_item,
                R.id.product_name, products);
        lv.setAdapter(adapter);

        inputSearch.addTextChangedListener(new TextWatcher() {

            @Override
            public void onTextChanged(CharSequence cs, int arg1, int arg2,
                    int arg3) {
                // When user changed the Text
                Video.this.adapter.getFilter().filter(cs);
            }

            @Override
            public void beforeTextChanged(CharSequence arg0, int arg1,
                    int arg2, int arg3) {
                // TODO Auto-generated method stub

            }

            @Override
            public void afterTextChanged(Editable arg0) {
                // TODO Auto-generated method stub
            }
        });
    }

    private void setContentView(int activityVideo) {
        // TODO Auto-generated method stub

    }
}

Eclipse显示方法findViewById（int）未定义为Video类型，构造函数ArrayAdapter（Video，int，int，String []）未定义。谢谢。

Answer 1

我检查了它正在运行的以下代码。创建新项目，然后尝试..

MainActivity.java

 package com.example.tesr;

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

import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.ActionBar;
import android.support.v4.app.Fragment;
import android.text.Editable;
import android.text.TextWatcher;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.EditText;
import android.widget.ListView;
import android.os.Build;

public class MainActivity extends ActionBarActivity {
    // List view
    private ListView lv;

    // Listview Adapter
    ArrayAdapter<String> adapter;

    // Search EditText
    EditText inputSearch;

    // ArrayList for Listview
    ArrayList<HashMap<String, String>> productList;

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

         // Listview Data
        String products[] = { "DEF", "POA",
                "ABC", "BCD" };

        lv = (ListView) findViewById(R.id.lv);
        inputSearch = (EditText) findViewById(R.id.editText1);
        // Adding items to listview
        adapter = new ArrayAdapter<String>(getApplicationContext(), R.layout.row,
                R.id.editText1, products);
        lv.setAdapter(adapter);

        inputSearch.addTextChangedListener(new TextWatcher() {

            @Override
            public void onTextChanged(CharSequence cs, int arg1, int arg2,
                    int arg3) {
                // When user changed the Text
                MainActivity.this.adapter.getFilter().filter(cs);
            }

            @Override
            public void beforeTextChanged(CharSequence arg0, int arg1,
                    int arg2, int arg3) {
                // TODO Auto-generated method stub

            }



            @Override
            public void afterTextChanged(Editable arg0) {
                // TODO Auto-generated method stub

            }
        });

        if (savedInstanceState == null) {
            getSupportFragmentManager().beginTransaction()
                    .add(R.id.container, new PlaceholderFragment()).commit();
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {

        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.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();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }

    /**
     * A placeholder fragment containing a simple view.
     */
    public static class PlaceholderFragment extends Fragment {

        public PlaceholderFragment() {
        }

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                Bundle savedInstanceState) {
            View rootView = inflater.inflate(R.layout.fragment_main, container,
                    false);
            return rootView;
        }
    }

}

activity_main.xml

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/container"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.example.tesr.MainActivity"
    tools:ignore="MergeRootFrame" >

    <EditText
        android:id="@+id/editText1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:ems="10" >
    </EditText>

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

</FrameLayout>

<强> row.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >
     <TextView
        android:id="@+id/editText1"
        android:textColor="#000"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:ems="10" >
   </TextView>

</LinearLayout>

Answer 2

将适配器中的this替换为getApplicationContext()我认为它可能有用。

Answer 3

您的Video正在延长Fragment。 Fragment没有方法findViewById。

扩展Fragment时，您需要在public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)中构建contentView。 View的方法为findViewById。

ArrayAdapter构造函数需要Context作为第一个参数。您可以使用fragment.getActivity()获取Context。

为您准备一些代码。

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    View v = inflater.inflate(R.layout.activity_video, container, false);
    lv = (ListView) v.findViewById(R.id.lv);
    inputSearch = (EditText) v.findViewById(R.id.editText1);
    adapter = new ArrayAdapter<String>(getActivity(), R.layout.activity_list_item,
            R.id.product_name, products);
    lv.setAdapter(adapter);
    return v;
}

findViewById和ArrayAdapter中的错误

3 个答案: