戴上動作條

Question

佈局

<?xml version="1.0" encoding="utf-8"?> 

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
xmlns:app="http://schemas.android.com/apk/res-auto" 
xmlns:tools="http://schemas.android.com/tools" 
android:layout_width="wrap_content" 
android:layout_height="match_parent" 
android:id="@+id/llist" 
tools:context="com.android.parteek.contentprovider.Main2Activity"> 

<android.support.v7.widget.SearchView 
android:layout_width="wrap_content" 
android:layout_height="wrap_content" 
android:id="@+id/serch"> 
</android.support.v7.widget.SearchView> 

<ListView 
    android:id="@+id/list" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    tools:context="com.android.parteek.contentprovider.Main2Activity"> 

</ListView> 

</LinearLayout> 

代碼

package com.android.parteek.contentprovider; 

import android.content.ContentResolver; 
import android.content.DialogInterface; 
import android.content.Intent; 
import android.database.Cursor; 
import android.support.v7.app.AlertDialog; 
import android.support.v7.app.AppCompatActivity; 
import android.os.Bundle; 
import android.support.v7.widget.SearchView; 
import android.util.Log; 
import android.view.Menu; 
import android.view.View; 
import android.widget.AdapterView; 
import android.widget.ListView; 
import android.widget.Toast; 

import java.util.ArrayList; 

public class Main2Activity extends AppCompatActivity implements AdapterView.OnItemLongClickListener, SearchView.OnQueryTextListener { 
ListView l; 
ArrayList<Bean> arrayList; 
UserAdapterr userAdapterr; 
ContentResolver contentResolver; 
SearchView searchView; 
Bean b,b1; 
int pos; 
void views(){ 
    l=(ListView)findViewById(R.id.list); 
    searchView=(SearchView)findViewById(R.id.serch); 

} 
@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main2); 
    views(); 
    contentResolver=getContentResolver(); 
    retrieve(); 
} 
@Override 
public boolean onCreateOptionsMenu(Menu menu) { 
    getMenuInflater().inflate(R.menu.searchmenu,menu); 
    searchView=(SearchView)menu.findItem(R.id.search).getActionView(); 
    searchView.setIconifiedByDefault(true); 
    searchView.setOnQueryTextListener(this); 
    searchView.setQueryHint("search....."); 

    return super.onCreateOptionsMenu(menu); 
} 


@Override 
public boolean onQueryTextSubmit(String query) { 
    return false; 
} 

@Override 
public boolean onQueryTextChange(String newText) { 
    return false; 
} 
} 

錯誤

java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v7.widget.SearchView.setIconifiedByDefault(boolean)' on a null object reference 
                         at com.android.parteek.contentprovider.Main2Activity.onCreateOptionsMenu(Main2Activity.java:147) 

Answer 1

一個搜索查看如果你想讓它在動作條，然後從活動中刪除。將其添加到searchmenu.xml。

你的錯誤與此這些線路，所以解決您在充氣

getMenuInflater().inflate(R.menu.searchmenu,menu); 
searchView=(SearchView)menu.findItem(R.id.search).getActionView(); 
searchView.setIconifiedByDefault(true); 

是XML文件，並可以有效地消除這種搜索查看

void views(){ 
    l=(ListView)findViewById(R.id.list); 
    // searchView=(SearchView)findViewById(R.id.serch); 

}