Error generating custom Listview

Question

Error generating custom Listview

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#1 by (4 votes)
#2 by (2 votes)

3

Hello,

I'm trying to implement a custom ListView on Android, but I'm not getting it. It's something simple, I've done it before, but I can not see where I'm wrong.

Adapter_Bluetooth.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">

    <RelativeLayout
        android:id="@+id/frmNome_Bluetooth"
        android:layout_width="wrap_content"
        android:layout_height="fill_parent">

        <TextView
            android:id="@+id/txtNome_Dispositivo"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Texto"
            android:textSize="50sp"
            android:textStyle="bold" />

        <RelativeLayout
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_below="@+id/txtNome_Dispositivo">

            <TextView
                android:id="@+id/txtCodigo_Dispositivo"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:textSize="20sp"
                android:text="Texto 2" />
        </RelativeLayout>
    </RelativeLayout>

</LinearLayout>

Activity_Listar_Bluetooth.xml :

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
    android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin"
    tools:context="br.ufscar.dc.controledepatrimonio.Forms.ListarBluetoothActivity">

    <ListView
        android:id="@+id/lstBluetooth"
        android:layout_width="wrap_content"
        android:layout_height="fill_parent"/>

</RelativeLayout>

BluetoothAdapert.java

package br.ufscar.dc.controledepatrimonio.Forms;

import android.bluetooth.BluetoothDevice;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;

import java.util.List;

import br.ufscar.dc.controledepatrimonio.R;

public class BluetoothAdapter extends BaseAdapter {
    private List<BluetoothDevice> dispostivos;
    private LayoutInflater inflater;
    private Context ctx;

    public BluetoothAdapter(Context ctx, List<BluetoothDevice> dispositivos) {
        this.dispostivos = dispositivos;
        this.ctx = ctx;
    }


    @Override
    public int getCount() {
        return dispostivos.size();
    }

    @Override
    public Object getItem(int position) {
        return dispostivos.get(position);
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        final BluetoothDevice dispositivo = (BluetoothDevice) getItem(position);
        final int posicao = position;
        View view = inflater.inflate(R.layout.adapter_bluetooth, null);

        TextView txtNomeDispositivo = (TextView) view.findViewById(R.id.txtNome_Dispositivo);
        txtNomeDispositivo.setText(dispositivo.getName());

        TextView txtCodigoDispositivo = (TextView) view.findViewById(R.id.txtCodigo_Dispositivo);
        txtCodigoDispositivo.setText(dispositivo.getAddress());

        return view;
    }
}

ListBluetoothActivity.java

package br.ufscar.dc.controledepatrimonio.Forms;

import android.bluetooth.BluetoothDevice;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.ListView;
import android.widget.Toast;

import java.util.ArrayList;
import java.util.List;

import br.ufscar.dc.controledepatrimonio.R;
import br.ufscar.dc.controledepatrimonio.Util.RFID.Bluetooth;
import br.ufscar.dc.controledepatrimonio.Util.RFID.BluetoothListener;

public class ListarBluetoothActivity extends AppCompatActivity implements BluetoothListener {
    private Bluetooth bluetooth = new Bluetooth();
    private final static int REQUEST_ENABLE_BT = 1;
    private List<BluetoothDevice> listaPareados = new ArrayList<BluetoothDevice>();

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

        try {
            switch (bluetooth.verificarEstado()) {
                case LIGADO:
                    listaPareados = bluetooth.getPareados();
                    ListView lstBluetooth = (ListView) findViewById(R.id.lstBluetooth);
                    BluetoothAdapter itemBluetooth = new BluetoothAdapter(this, listaPareados);

                    lstBluetooth.setAdapter(itemBluetooth);
                    break;
                case DESLIGADO:
                    Intent enableBtIntent = new Intent(bluetooth.getDispositivo().ACTION_REQUEST_ENABLE);
                    startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
                    break;
                case NAO_COMPATIVEL:
                    Toast.makeText(getApplicationContext(), R.string.msg_bluetooth_nao_suportado, Toast.LENGTH_SHORT).show();
                    break;
            }
        }
        catch (Exception ex) {
            Log.e("ERRO:", ex.getMessage());
        }
    }

    @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_listar_bluetooth, 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();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }

    @Override
    public void action(String action) {

    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        // TODO Auto-generated method stub

        if (requestCode == REQUEST_ENABLE_BT) {
            switch (resultCode) {
                case RESULT_CANCELED:
                    finish();
                    break;
            }
        }
    }
}

Log Error

08-06 10:54:08.955  25363-25363/? E/Zygote﹕ MountEmulatedStorage()
08-06 10:54:08.955  25363-25363/? E/Zygote﹕ v2
08-06 10:54:08.955  25363-25363/? I/SELinux﹕ Function: selinux_compare_spd_ram, SPD-policy is existed. and_ver=SEPF_GT-I9505_5.0.1 ver=27
08-06 10:54:08.955  25363-25363/? I/libpersona﹕ KNOX_SDCARD checking this for 10214
08-06 10:54:08.955  25363-25363/? I/libpersona﹕ KNOX_SDCARD not a persona
08-06 10:54:08.965  25363-25363/? I/SELinux﹕ Function: selinux_compare_spd_ram , priority [1] , priority version is VE=SEPF_GT-I9505_5.0.1_0027
08-06 10:54:08.965  25363-25363/? E/SELinux﹕ [DEBUG] get_category: variable seinfo: default sensitivity: NULL, cateogry: NULL
08-06 10:54:08.965  25363-25363/? I/art﹕ Late-enabling -Xcheck:jni
08-06 10:54:09.035  25363-25363/? D/ResourcesManager﹕ creating new AssetManager and set to /data/app/br.ufscar.dc.controledepatrimonio-1/base.apk
08-06 10:54:09.185  25363-25363/? D/Activity﹕ performCreate Call secproduct feature valuefalse
08-06 10:54:09.185  25363-25363/? D/Activity﹕ performCreate Call debug elastic valuetrue
08-06 10:54:09.205  25363-25411/? D/OpenGLRenderer﹕ Render dirty regions requested: true
08-06 10:54:09.235  25363-25411/? I/Adreno-EGL﹕ <qeglDrvAPI_eglInitialize:410>: EGL 1.4 QUALCOMM build:  ()
    OpenGL ES Shader Compiler Version: E031.25.03.06
    Build Date: 01/24/15 Sat
    Local Branch: AF11_RB1_AU15
    Remote Branch:
    Local Patches:
    Reconstruct Branch:
08-06 10:54:09.235  25363-25411/? I/OpenGLRenderer﹕ Initialized EGL, version 1.4
08-06 10:54:09.255  25363-25411/? D/OpenGLRenderer﹕ Enabling debug mode 0
08-06 10:54:09.395  25363-25363/? I/Timeline﹕ Timeline: Activity_idle id: android.os.BinderProxy@2f59a50b time:94052600
08-06 10:54:10.206  25363-25363/? D/ViewRootImpl﹕ ViewPostImeInputStage ACTION_DOWN
08-06 10:54:10.286  25363-25363/? I/Timeline﹕ Timeline: Activity_launch_request id:br.ufscar.dc.controledepatrimonio time:94053490
08-06 10:54:10.356  25363-25363/? D/AbsListView﹕ Get MotionRecognitionManager
08-06 10:54:10.366  25363-25363/? D/Activity﹕ performCreate Call secproduct feature valuefalse
08-06 10:54:10.366  25363-25363/? D/Activity﹕ performCreate Call debug elastic valuetrue
08-06 10:54:10.376  25363-25363/? D/AndroidRuntime﹕ Shutting down VM
08-06 10:54:10.376  25363-25363/? E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: br.ufscar.dc.controledepatrimonio, PID: 25363
    java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View android.view.LayoutInflater.inflate(int, android.view.ViewGroup)' on a null object reference
            at br.ufscar.dc.controledepatrimonio.Forms.BluetoothAdapter.getView(BluetoothAdapter.java:45)
            at android.widget.AbsListView.obtainView(AbsListView.java:2823)
            at android.widget.ListView.measureHeightOfChildren(ListView.java:1290)
            at android.widget.ListView.onMeasure(ListView.java:1202)
            at android.view.View.measure(View.java:18596)
            at android.widget.RelativeLayout.measureChildHorizontal(RelativeLayout.java:728)
            at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:464)
            at android.view.View.measure(View.java:18596)
            at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5827)
            at android.widget.FrameLayout.onMeasure(FrameLayout.java:430)
            at android.support.v7.internal.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:124)
            at android.view.View.measure(View.java:18596)
            at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5827)
            at android.support.v7.internal.widget.ActionBarOverlayLayout.onMeasure(ActionBarOverlayLayout.java:444)
            at android.view.View.measure(View.java:18596)
            at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5827)
            at android.widget.FrameLayout.onMeasure(FrameLayout.java:430)
            at android.view.View.measure(View.java:18596)
            at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5827)
            at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1435)
            at android.widget.LinearLayout.measureVertical(LinearLayout.java:721)
            at android.widget.LinearLayout.onMeasure(LinearLayout.java:612)
            at android.view.View.measure(View.java:18596)
            at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5827)
            at android.widget.FrameLayout.onMeasure(FrameLayout.java:430)
            at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2897)
            at android.view.View.measure(View.java:18596)
            at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2248)
            at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1306)
            at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1548)
            at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1191)
            at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6642)
            at android.view.Choreographer$CallbackRecord.run(Choreographer.java:777)
            at android.view.Choreographer.doCallbacks(Choreographer.java:590)
            at android.view.Choreographer.doFrame(Choreographer.java:560)
            at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:763)
            at android.os.Handler.handleCallback(Handler.java:739)
            at android.os.Handler.dispatchMessage(Handler.java:95)
            at android.os.Looper.loop(Looper.java:145)
            at android.app.ActivityThread.main(ActivityThread.java:5942)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1400)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1195)
08-06 10:54:11.718  25363-25363/? I/Process﹕ Sending signal. PID: 25363 SIG: 9

I'm still hitting my head here, but if anyone can give me a light where I'm wrong, I thank you immensely!

java android listview

asked by anonymous 06.08.2015 / 15:56

2 answers

2

In class "BluetoothAdapert.java" replace the line:

View view = inflater.inflate(R.layout.adapter_bluetooth, null);

by this:

View view = inflater.inflate(R.layout.adapter_bluetooth, parent, null);

Your logcat is saying that the "ViewGroup" attribute is null, you did not pass it as a parameter.

'android.view.View android.view.LayoutInflater.inflate(int, android.view.ViewGroup)' on a null object reference

I'm not sure what to do.

06.08.2015 / 16:14

Show an object / variable with different names in R? Strange behavior when displaying an attribute using click ();

score 4 · Accepted Answer

You forgot to instantiate your LayoutInflater .

Inside your BluetoothAdapter() constructor, try something like this:

public BluetoothAdapter(Context ctx, List<BluetoothDevice> dispositivos) {
    this.dispostivos = dispositivos;
    this.ctx = ctx;
    inflater = LayoutInflater.from(ctx);
}