[英]Why is my Bluetooth application Crashing
我正在研究藍牙應用程序,但我的應用程序崩潰。這是我的MainActivity.java
package com.race_gurram.bluetoothadapter;
import java.util.ArrayList;
import java.util.Set;
import android.app.Activity;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
import android.widget.Toast;
public class MainActivity extends Activity {
private Button on, off, get, bring;
private BluetoothAdapter BA;
private Set<BluetoothDevice> pairedDevices;
private ListView lv;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
on = (Button) findViewById(R.id.on);
off = (Button) findViewById(R.id.off);
get = (Button) findViewById(R.id.get);
bring = (Button) findViewById(R.id.list);
lv = (ListView) findViewById(R.id.listView1);
BA = BluetoothAdapter.getDefaultAdapter();
}
public void on(View view)
{
if(!BA.isEnabled())
{
Intent turnOn = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(turnOn,0);
Toast.makeText(getApplicationContext(), "Turned On", Toast.LENGTH_SHORT).show();
}
else
{
Toast.makeText(getApplicationContext(), "Already on", Toast.LENGTH_SHORT).show();
}
}
public void list(View view)
{
pairedDevices = BA.getBondedDevices();
ArrayList list = new ArrayList();
for(BluetoothDevice bt : pairedDevices)
list.add(BA.getName());
Toast.makeText(getApplicationContext(), "Searching for devices", Toast.LENGTH_SHORT).show();
final ArrayAdapter adapter = new ArrayAdapter(this,android.R.layout.simple_list_item_1,list);
lv.setAdapter(adapter);
}
public void get()
{
Intent getVisible = new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE);
startActivityForResult(getVisible,0);
}
public void off()
{
BA.disable();
Toast.makeText(getApplicationContext(), "Turned off", Toast.LENGTH_SHORT).show();
}
@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;
}
}
這是我的activity.xml文件
<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:orientation="vertical"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity" >
<ScrollView
android:id="@+id/scrollView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_alignParentLeft="true"
android:layout_alignParentRight="true"
android:layout_alignParentTop="true" >
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<Button
android:id="@+id/on"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="on"
android:text="@string/on" />
<Button
android:id="@+id/get"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="get"
android:text="@string/get" />
<Button
android:id="@+id/list"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="list"
android:text="@string/bring" />
<Button
android:id="@+id/off"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="off"
android:text="@string/off" />
<ListView
android:id="@+id/listView1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:visibility="visible" >
</ListView>
</LinearLayout>
</ScrollView>
</RelativeLayout>
每當我點擊一個按鈕時,應用程序崩潰......請幫我解決這個問題..提前謝謝。
在get和off方法中,應該有一個View參數,對吧?
public void get(View v) {
Intent getVisible = new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE);
startActivityForResult(getVisible,0);
} public void off(View v) {
BA.disable();
Toast.makeText(getApplicationContext(), "Turned off", Toast.LENGTH_SHORT).show(); }
也許就是當你點擊列表按鈕時。 假設手機有0個綁定設備,paired.getBondedDevices()可能會返回null並且程序因NullPointerException而崩潰。
pairedDevices = BA.getBondedDevices();
ArrayList list = new ArrayList();
if(pairedDevices != null) {
for(BluetoothDevice bt : pairedDevices)
list.add(BA.getName());
}
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