Question

这是我的MainActivity.java文件

public class MainActivity extends Activity implements OnItemSelectedListener{

private Spinner spinner;
protected static final String[]paths = {".com", ".org", ".net"};
protected String name,dom,stat;
private boolean softInputActive;
final EditText edit =  (EditText) findViewById(R.id.editText1);


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    spinner = (Spinner)findViewById(R.id.spinner);
    ArrayAdapter<String>adapter = new ArrayAdapter <String(this,android.R.layout.simple_spinner_item,paths);

    adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    spinner.setAdapter(adapter);
    spinner.setOnItemSelectedListener(this);
}

@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;
}



@Override
public void onNothingSelected(AdapterView<?> arg0) {
    // TODO Auto-generated method stub
}

@Override
public void onWindowFocusChanged(boolean hasFocus) {

    super.onWindowFocusChanged(hasFocus);

    InputMethodManager IMEManager = (InputMethodManager) getSystemService(Context.INPUT_METHOD_SERVICE);

    View focusedView = getCurrentFocus();

    // Find the primitive focused view (not ViewGroup)
    while (focusedView instanceof ViewGroup) {
        focusedView = ((ViewGroup) focusedView).getFocusedChild();
    }


    if (hasFocus) {

        if (focusedView instanceof EditText && focusedView.isEnabled() && !IMEManager.isActive(focusedView)) {
            IMEManager.toggleSoftInput(InputMethodManager.SHOW_FORCED, 0);
            softInputActive = true;
        }
    } else if (softInputActive) {
        if (focusedView != null && IMEManager.isActive()) {
            IMEManager.toggleSoftInput(InputMethodManager.SHOW_IMPLICIT, 0);
        }
        softInputActive = false;
    }

}

@Override
public void onItemSelected(AdapterView<?> parent, View v, int position, long id) {
    if(position == 0)
    {
        name = edit.getText().toString();
        dom = paths[0];
    }
    else if (position == 1)
    {
        name = edit.getText().toString();
        dom = paths[1];
    }
    else if(position == 2)
    {
        name = edit.getText().toString();
        dom = paths[2];
    }


    RequestParams params = new RequestParams();
    params.put("src", name);
    params.put("dom", dom);

    NetActivity.post("mhs/", params, new AsyncHttpResponseHandler() {

        @Override
        public void onSuccess(String response) {

            final RequestParams para = new RequestParams();
                NetActivity.get("mts/default.asp?", para, new AsyncHttpResponseHandler() {

                    @Override
                    public void onSuccess(String Response) {
                        para.put("status",stat);

                    }
            });
        }

        @Override
        public void onFailure(Throwable error, String content) {
            Toast.makeText(getApplicationContext(), "Page Not Found!!",Toast.LENGTH_LONG).show();
        }
    });
}

}

这是我的NetActivity.java文件

 public class NetActivity extends Activity{

 private static final String BASE_URL = "http://docs.google.com/";

 private static AsyncHttpClient client = new AsyncHttpClient();

 public static void get(String relativeURL, RequestParams params, AsyncHttpResponseHandler responseHandler) {
      //System.out.println(getAbsoluteUrl(relativeURL));
      client.get(getAbsoluteUrl(relativeURL), params, responseHandler);
      client.getHttpClient().getParams().setParameter(ClientPNames.ALLOW_CIRCULAR_REDIRECTS, true);
  }


 public static void post(String relativeURL, RequestParams params, AsyncHttpResponseHandler responseHandler) {
    //System.out.print(getAbsoluteUrl(relativeURL)) ; 
    client.post(getAbsoluteUrl(relativeURL), params, responseHandler);
    client.getHttpClient().getParams().setParameter(ClientPNames.ALLOW_CIRCULAR_REDIRECTS, true);
  }


 private static String getAbsoluteUrl(String relativeUrl) {
      return BASE_URL + relativeUrl;
  }

}

这是我的activity_main.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:gravity="clip_horizontal"
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" >

<TextView
    android:id="@+id/textView1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentLeft="true"
    android:layout_alignParentTop="true"
    android:layout_marginTop="111dp"
    android:text="@string/hello_world" />

<EditText
    android:id="@+id/editText1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignLeft="@+id/textView1"
    android:layout_below="@+id/textView1"
    android:layout_marginTop="16dp"
    android:ems="10" />

<Spinner
    android:id="@+id/spinner"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignTop="@+id/editText1"
    android:layout_toRightOf="@+id/editText1" />

LOGCAT详细信息：

06-09 16:42:45.557: E/Trace(917): error opening trace file: No such file or directory (2)
06-09 16:42:45.657: W/ActivityThread(917): Application com.example.mtsdomain is waiting for the debugger on port 8100...
06-09 16:42:45.707: I/System.out(917): Sending WAIT chunk
06-09 16:42:45.747: I/dalvikvm(917): Debugger is active
06-09 16:42:45.917: I/System.out(917): Debugger has connected
06-09 16:42:45.917: I/System.out(917): waiting for debugger to settle...
06-09 16:42:46.127: I/System.out(917): waiting for debugger to settle...
06-09 16:42:46.327: I/System.out(917): waiting for debugger to settle...
06-09 16:42:46.527: I/System.out(917): waiting for debugger to settle...
06-09 16:42:46.793: I/System.out(917): waiting for debugger to settle...
06-09 16:42:46.987: I/System.out(917): waiting for debugger to settle...
06-09 16:42:47.197: I/System.out(917): waiting for debugger to settle...
06-09 16:42:47.399: I/System.out(917): waiting for debugger to settle...
06-09 16:42:47.600: I/System.out(917): waiting for debugger to settle...
06-09 16:42:47.831: I/System.out(917): debugger has settled (1517)

我认为代码中存在一些错误或者可能以错误的方式宣布某事因为当我调试它它显示nullpointerexception错误我是新手。提前谢谢。

Answer 1

也许这是错的：

final EditText edit =  (EditText) findViewById(R.id.editText1);

您在对视图进行夸大之前定义了这一点，因此edit为null。那你在这里有一个NPE：

public void onItemSelected(AdapterView<?> parent, View v, int position, long id) {
    if(position == 0)
    {
        name = edit.getText().

Answer 2

更改

final EditText edit =  (EditText) findViewById(R.id.editText1);

到

EditText edit;

并将以下行添加到onCreate()：

edit =  (EditText) findViewById(R.id.editText1);

我在这段代码中遇到nullpointerexception错误

2 个答案: