在 ActionBar 中使用 SearchView

Question

我正在尝试运行一个简单的代码，当用户单击 Search action.

时显示 SearchView

当我运行 application 时，它以 致命异常.

关闭

我的代码

MainActivity.java

package luizugliano.com.br.customactionbar;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.SearchView;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);

}

@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_main, menu);

    MenuItem item = menu.findItem(R.id.action_search);
    SearchView searchView = (SearchView) item.getActionView();
    searchView.setOnQueryTextListener(onSearch());
    return true;
}

private SearchView.OnQueryTextListener onSearch() {
    return new SearchView.OnQueryTextListener(){
        @Override
        public boolean onQueryTextSubmit(String query) {
            // Usuário fez a busca
            toastMessage("Buscar o texto: " + query);
            return false;
        }
        @Override
        public boolean onQueryTextChange(String newText) {
            // Mudou o texto digitado
            return false;
        }
    };
}

@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_search) {
        toastMessage("Search!");
        return true;
    } else if (id == R.id.action_refresh){
        toastMessage("Refresh!");
        return true;
    } else if (id == R.id.action_settings){
        toastMessage("Settings!");
        return true;
    }

    return super.onOptionsItemSelected(item);
}

private void toastMessage(String message){
    Toast.makeText(this, message, Toast.LENGTH_SHORT).show();
}
}

menu_main.xml

<menu 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" tools:context=".MainActivity">
<item android:id="@+id/action_search" android:title="@string/action_search"
    android:orderInCategory="100" android:icon="@drawable/ic_action_search" app:showAsAction="always"
    android:actionViewClass="android.widget.SearchView"/>
<item android:id="@+id/action_refresh" android:title="@string/action_refresh"
    android:orderInCategory="100" android:icon="@drawable/ic_action_refresh" app:showAsAction="always" />
<item android:id="@+id/action_settings" android:title="@string/action_settings"
    android:orderInCategory="100" app:showAsAction="never" />

logcat信息

10-20 00:30:21.327 806-806/luizugliano.com.br.customactionbar D/AndroidRuntime: 10-20 00:30:21.327 806-806/luizugliano.com.br.customactionbar E/AndroidRuntime: 10-20 00:30:21.327 806-806/luizugliano.com.br.customactionbar E/AndroidRuntime: 10-20 00:30:21.327 806-806/luizugliano.com.br.customactionbar E/AndroidRuntime: 10-20 00:30:21.327 806-806/luizugliano.com.br.customactionbar E/AndroidRuntime: 10-20 00:30:21.327 806-806/luizugliano.com.br.customactionbar E/AndroidRuntime: 10-20 00:30:21.327 806-806/luizugliano.com.br.customactionbar E/AndroidRuntime: 10-20 00:30:21.327 806-806/luizugliano.com.br.customactionbar E/AndroidRuntime: 10-20 00:30:21.327 806-806/luizugliano.com.br.customactionbar E/AndroidRuntime: 10-20 00:30:21.327 806-806/luizugliano.com.br.customactionbar E/AndroidRuntime: 10-20 00:30:21.327 806-806/luizugliano.com.br.customactionbar E/AndroidRuntime: 10-20 00:30:21.327 806-806/luizugliano.com.br.customactionbar E/AndroidRuntime: 10-20 00:30:21.327 806-806/luizugliano.com.br.customactionbar E/AndroidRuntime: 10-20 00:30:21.327 806-806/luizugliano.com.br.customactionbar E/AndroidRuntime: 10-20 00:30:21.327 806-806/luizugliano.com.br.customactionbar E/AndroidRuntime: 10-20 00:30:21.327 806-806/luizugliano.com.br.customactionbar E/AndroidRuntime: 10-20 00:30:21.327 806-806/luizugliano.com.br.customactionbar E/AndroidRuntime: 10-20 00:30:21.327 806-806/luizugliano.com.br.customactionbar E/AndroidRuntime: 10-20 00:30:21.327 806-806/luizugliano.com.br.customactionbar E/AndroidRuntime: 10-20 00:30:21.686 806-820/luizugliano.com.br.customactionbar I/art: Background 10-20 00:30:35.570 806-806/? I/Process: Sending signal. PID: 806 SIG: 9 Shutting down VM FATAL EXCEPTION: main Process: luizugliano.com.br.customactionbar, PID: 806 java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.SearchView.setOnQueryTextListener(android.widget.SearchView$OnQueryTextListener)' on a null object reference at luizugliano.com.br.customactionbar.MainActivity.onCreateOptionsMenu(MainActivity.java:29) at android.app.Activity.onCreatePanelMenu(Activity.java:2846) at android.support.v4.app.FragmentActivity.onCreatePanelMenu(FragmentActivity.java:298) at android.support.v7.internal.view.WindowCallbackWrapper.onCreatePanelMenu(WindowCallbackWrapper.java:85) at android.support.v7.app.AppCompatDelegateImplBase$AppCompatWindowCallbackBase.onCreatePanelMenu(AppCompatDelegateImplBase.java:243) at android.support.v7.internal.view.WindowCallbackWrapper.onCreatePanelMenu(WindowCallbackWrapper.java:85) at android.support.v7.internal.app.ToolbarActionBar.populateOptionsMenu(ToolbarActionBar.java:448) at android.support.v7.internal.app.ToolbarActionBar.run(ToolbarActionBar.java:65) at android.os.Handler.handleCallback(Handler.java:739) at android.os.Handler.dispatchMessage(Handler.java:95) at android.os.Looper.loop(Looper.java:148) at android.app.ActivityThread.main(ActivityThread.java:5417) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) partial concurrent mark sweep GC freed 205(8KB) AllocSpace objects, 0(0B) LOS objects, 40% free, 5MB/8MB, paused 41.133ms total 119.832ms

Answer 1

您需要与 Java 和 XML 代码库中搜索视图访问支持库的使用保持一致。不正确使用它会导致 NPE。

Answer 2

错误信息 java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.SearchView.setOnQueryTextListener(android.widget.SearchView$OnQueryTextListener)' on a null object reference 表示正在尝试调用 在 null searchView 上设置 OnQueryTextListener。

在你的menu_main.xml中，更改

android:actionViewClass="android.widget.SearchView"

到

app:actionViewClass="android.support.v7.widget.SearchView"

然后在您的 MainActivity.java 中更改

SearchView searchView = (SearchView) item.getActionView();

和

SearchView searchView = (SearchView) MenuItemCompat.getActionView(menu.findItem(R.id.action_search));

在 ActionBar 中使用 SearchView

Using SearchView in ActionBar

android

android-actionbar

searchview

android-studio