我需要一些帮助来完成我的工作室，我在Android上有一个带有WebService的应用程序，方法
List<Servicos> servicos = new ServicoReq().getListaServicos();
工作正常，我正在尝试编译此代码，如下：
public class ConsultaServicos extends MainActivity implements OnItemClickListener{
//private static final String CATEGORIA = "cardapio";
private Spinner spinnerServicos;
private long idServico=0;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.consulta_servicos);
//Identifica o Spinner no layout
spinnerServicos = (Spinner) findViewById(R.id.spinnerServicos);
List<Servicos> servicos = new ServicoReq().getListaServicos();
List<String> lista = new ArrayList<String>();
lista.add("um");
//Cria um ArrayAdapter usando um padrão de layout da classe R do android, passando o ArrayList nome dos serviço
ArrayAdapter<Servicos> arrayAdapter = new ArrayAdapter<Servicos>(this, android.R.layout.simple_spinner_dropdown_item, servicos);
spinnerServicos.setAdapter(arrayAdapter);
//Método do Spinner para capturar o item selecionado
spinnerServicos.setOnItemSelectedListener(new OnItemSelectedListener() {
@Override
public void onItemSelected(AdapterView<?> parent, View v, int posicao, long id) {
//pega nome pela posição
Servicos serv = (Servicos)parent.getSelectedItem();
idServico = serv.getId();
}
@Override
public void onNothingSelected(AdapterView<?> parent) {
}
});
Button btListarEstabelecimentoCidade = (Button) findViewById(R.id.btListarEstabelecimentosCidade);
btListarEstabelecimentoCidade.setOnClickListener(this);
}
public void onClick(View v) {
Intent it;
switch (v.getId()){
case R.id.btListarEstabelecimentosCidade:
it = new Intent("LISTAGEM_ESTABELECIMENTO");
//Seta o que será passado CIDADE e Reseta TODOS OUTROS!
it.putExtra("BUSCA_POR_CIDADE", "");
it.putExtra("BUSCA_POR_SERVICOS", idServico);
startActivity(it);
}
}
@Override
public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3) {
// TODO Auto-generated method stub
}
}
但这个错误信息令我发疯：
05-27 02:02:39.629: W/dalvikvm(834): threadid=1: thread exiting with uncaught exception (group=0x40015560)
05-27 02:02:39.650: E/AndroidRuntime(834): FATAL EXCEPTION: main
05-27 02:02:39.650: E/AndroidRuntime(834): java.lang.RuntimeException: Unable to start activity ComponentInfo{br.projetoandroid/br.projetoandroid.ConsultaServicos}: java.lang.NullPointerException
05-27 02:02:39.650: E/AndroidRuntime(834): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647)
05-27 02:02:39.650: E/AndroidRuntime(834): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
05-27 02:02:39.650: E/AndroidRuntime(834): at android.app.ActivityThread.access$1500(ActivityThread.java:117)
05-27 02:02:39.650: E/AndroidRuntime(834): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
05-27 02:02:39.650: E/AndroidRuntime(834): at android.os.Handler.dispatchMessage(Handler.java:99)
05-27 02:02:39.650: E/AndroidRuntime(834): at android.os.Looper.loop(Looper.java:123)
05-27 02:02:39.650: E/AndroidRuntime(834): at android.app.ActivityThread.main(ActivityThread.java:3683)
05-27 02:02:39.650: E/AndroidRuntime(834): at java.lang.reflect.Method.invokeNative(Native Method)
05-27 02:02:39.650: E/AndroidRuntime(834): at java.lang.reflect.Method.invoke(Method.java:507)
05-27 02:02:39.650: E/AndroidRuntime(834): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
05-27 02:02:39.650: E/AndroidRuntime(834): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
05-27 02:02:39.650: E/AndroidRuntime(834): at dalvik.system.NativeStart.main(Native Method)
05-27 02:02:39.650: E/AndroidRuntime(834): Caused by: java.lang.NullPointerException
05-27 02:02:39.650: E/AndroidRuntime(834): at br.projetoandroid.ConsultaServicos.onCreate(ConsultaServicos.java:53)
05-27 02:02:39.650: E/AndroidRuntime(834): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
05-27 02:02:39.650: E/AndroidRuntime(834): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
05-27 02:02:39.650: E/AndroidRuntime(834): ... 11 more
感谢您的理解！
答案 0 :(得分：0)
我将上面的代码更改为以下代码：
公共类ConsultaServicos扩展了Activity实现OnItemClickListener { // private static final String CATEGORIA =“cardapio”; 私人Spinner spinnerServicos; private long idServico = 0;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.consulta_servicos);
List<Servicos> l = new ServicoReq().getListaServicos();
spinnerServicos = (Spinner) findViewById(R.id.spinnerServicos);
ArrayAdapter<Servicos> servicoAdapter = new ArrayAdapter<Servicos>(this, android.R.layout.simple_spinner_item, l);
spinnerServicos.setAdapter(servicoAdapter);
spinnerServicos.setPrompt("Selecione um serviço");
spinnerServicos.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
@Override
public void onItemSelected(AdapterView<?> parent, View v, int posicao, long id) {
//pega nome pela posição
Servicos serv = (Servicos)parent.getSelectedItem();
idServico = serv.getId();
Log.i(">>>>>>>>>>>ID SERVIÇO:", Long.toString(idServico));
}
@Override
public void onNothingSelected(AdapterView<?> parent) {
}
});
getListenerButtonListaEstabelecimento();
}
public void getListenerButtonListaEstabelecimento(){
Button btListarEstabelecimentoServico = (Button) findViewById(R.id.btListarEstabelecimentosServicos);
btListarEstabelecimentoServico.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
Intent it;
switch (v.getId()){
case R.id.btListarEstabelecimentosServicos:
it = new Intent("LISTAGEM_ESTABELECIMENTO");
//Seta o que será passado CIDADE e Reseta TODOS OUTROS!
it.putExtra("BUSCA_POR_CIDADE", "");
it.putExtra("BUSCA_POR_SERVICOS", idServico);
startActivity(it);
}
}
});
}
@Override
public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3) {
// TODO Auto-generated method stub
}
}
将按钮移出onCreate。