Java 当按钮被选中时,我的第二个android活动不会启动
我的MainActivity在所有小部件工作的情况下打开,但当我选择按钮打开第二个活动时,它无法打开,应用程序崩溃。Eclipse没有显示任何错误 我的主要活动课:Java 当按钮被选中时,我的第二个android活动不会启动,java,android,xml,Java,Android,Xml,我的MainActivity在所有小部件工作的情况下打开,但当我选择按钮打开第二个活动时,它无法打开,应用程序崩溃。Eclipse没有显示任何错误 我的主要活动课: public class MainActivity extends FragmentActivity { private int dYear; private int dMonth; private int dDay; private int rYear; private int rMonth; private int rDay
public class MainActivity extends FragmentActivity {
private int dYear;
private int dMonth;
private int dDay;
private int rYear;
private int rMonth;
private int rDay;
static final int dDATE_DIALOG_ID = 0;
static final int rDATE_DIALOG_ID = 1;
private RadioButton buttonO = null;
private RadioButton buttonR = null;
private TableRow tr;
TextView txD, txR;
private Button btnDepart,btnReturn, btnSubmit,btnClose;
private Spinner noOfPassengersSpinner,departureSpinner,returnSpinner;
private CheckBox tandCCB;
final Context context = this;
private Bundle basket;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
buttonO = (RadioButton) findViewById(R.id.radioO);
buttonR = (RadioButton) findViewById(R.id.radioR);
txD=(TextView)findViewById(R.id.tvDepartureDate);
txR=(TextView)findViewById(R.id.tvReturnDate);
btnDepart = (Button)findViewById(R.id.btnDepart);
btnReturn = (Button)findViewById(R.id.btnReturn);
tr = (TableRow)findViewById(R.id.tableRow5);
btnSubmit = (Button)findViewById(R.id.btnSubmit);
btnClose = (Button)findViewById(R.id.btnClose);
noOfPassengersSpinner = (Spinner)findViewById(R.id.noOfPassengersSpinner);
departureSpinner = (Spinner)findViewById(R.id.departureSpinner);
returnSpinner = (Spinner)findViewById(R.id.returnSpinner);
tandCCB = (CheckBox)findViewById(R.id.tandCCB);
final Calendar dC = Calendar.getInstance();
final Calendar rC = Calendar.getInstance();
dYear = dC.get(Calendar.YEAR);
dMonth = dC.get(Calendar.MONTH);
dDay = dC.get(Calendar.DAY_OF_MONTH);
rYear = rC.get(Calendar.YEAR);
rMonth = rC.get(Calendar.MONTH);
rDay = rC.get(Calendar.DAY_OF_MONTH);
updateDisplay();
tandCCB.setOnCheckedChangeListener(new OnCheckedChangeListener()
{
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked)
{
if(isChecked){
btnSubmit.setEnabled(true);
}
else{
btnSubmit.setEnabled(false);
}
}
});
this.btnClose.setOnClickListener(new OnClickListener()
{
public void onClick(View v)
{
finish();
System.exit(0);
}
});
this.btnSubmit.setOnClickListener(new OnClickListener()
{
public void onClick(View v)
{
String depAir = departureSpinner.getSelectedItem().toString();
String desAir = returnSpinner.getSelectedItem().toString();
int numOfPass = Integer.parseInt(noOfPassengersSpinner.getSelectedItem().toString());
basket.putString("departureAir", depAir);
basket.putString("destenationAir", desAir);
basket.putInt("numOfPass", numOfPass);
basket.putString("depDate", txD.getText().toString());
String type = "";
if(buttonR.isChecked()){
String returnDate = txR.getText().toString();
basket.putString("returnDate", returnDate);
type = "Return";
}
else{
type = "Oneway";
}
basket.putString("type", type);
Intent intent = new Intent(context, Second.class);
intent.putExtras(basket);
startActivity(intent);
}
});
this.buttonO.setOnClickListener(new OnClickListener()
{
public void onClick(View v)
{
tr.setVisibility(View.GONE);
}
});
this.buttonR.setOnClickListener(new OnClickListener()
{
public void onClick(View v)
{
tr.setVisibility(View.VISIBLE);
}
});
this.btnDepart.setOnClickListener(new OnClickListener()
{
public void onClick(View v)
{
showDialog(dDATE_DIALOG_ID);
}
});
this.btnReturn.setOnClickListener(new OnClickListener()
{
public void onClick(View v)
{
showDialog(rDATE_DIALOG_ID);
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
private void updateDisplay() {
txD.setText(
new StringBuilder()
// Month is 0 based so add 1
.append(dYear).append("-")
.append(dMonth + 1).append("-")
.append(dDay).append(" ")
);
txR.setText(
new StringBuilder()
.append(rYear).append("-")
.append(rMonth + 1).append("-")
.append(rDay).append(" ")
);
}
private DatePickerDialog.OnDateSetListener dDateSetListener =
new DatePickerDialog.OnDateSetListener() {
public void onDateSet(DatePicker view, int year,
int monthOfYear, int dayOfMonth) {
dYear = year;
dMonth = monthOfYear;
dDay = dayOfMonth;
updateDisplay();
}
};
private DatePickerDialog.OnDateSetListener rDateSetListener =
new DatePickerDialog.OnDateSetListener() {
public void onDateSet(DatePicker view, int year,
int monthOfYear, int dayOfMonth) {
rYear = year;
rMonth = monthOfYear;
rDay = dayOfMonth;
updateDisplay();
}
};
@Override
protected Dialog onCreateDialog(int id) {
switch (id) {
case dDATE_DIALOG_ID:
return new DatePickerDialog(this,
dDateSetListener,
dYear, dMonth, dDay);
case rDATE_DIALOG_ID:
return new DatePickerDialog(this,
rDateSetListener,
rYear, dMonth, rDay);
}
return null;
}
}
我的第二项活动是:
public class Second extends Activity {
private TextView typeTv, departureTv,returnTv,departureDateTv,returnDateTv,noOfPassengersTv,tvReturnDateLbl;
private RadioButton buttonR = null;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.second);
typeTv = (TextView)findViewById(R.id.typeTv);
departureTv = (TextView)findViewById(R.id.departureTv);
returnTv = (TextView)findViewById(R.id.returnTv);
departureDateTv= (TextView)findViewById(R.id.departureTv);
returnDateTv= (TextView)findViewById(R.id.returneDateTv);
noOfPassengersTv = (TextView)findViewById(R.id.noOfPassengersTv);
buttonR = (RadioButton) findViewById(R.id.radioR);
tvReturnDateLbl = (TextView)findViewById(R.id.tvReturnDateLbl);
Intent i = getIntent();//MAking an intent called i
Bundle basket = this.getIntent().getExtras();
String tTv = basket.getString("type");
String dTv = basket.getString("departureAir");
String rTv = basket.getString("destinationAir");
String dDTv = basket.getString("depDateTv");
int nOPTv = basket.getInt("numOfPass");
if(buttonR.isChecked()){
String rDTv = basket.getString("returnDate");
returnDateTv.setText(rDTv);
}
else{
returnDateTv.setVisibility(View.GONE);
tvReturnDateLbl.setVisibility(View.GONE);
}
typeTv.setText(tTv);
departureTv.setText(dTv);
returnTv.setText(rTv);
departureDateTv.setText(dDTv);
noOfPassengersTv.setText(""+nOPTv);
}
}
最后,我的清单文件是:
我的新logcat
04-25 19:38:14.443: E/Trace(1155): error opening trace file: No such file or directory (2)
04-25 19:38:15.282: D/gralloc_goldfish(1155): Emulator without GPU emulation detected.
04-25 19:38:19.251: D/AndroidRuntime(1155): Shutting down VM
04-25 19:38:19.251: W/dalvikvm(1155): threadid=1: thread exiting with uncaught exception (group=0x40a13300)
04-25 19:38:19.281: E/AndroidRuntime(1155): FATAL EXCEPTION: main
04-25 19:38:19.281: E/AndroidRuntime(1155): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.assignment2/com.example.assignment2.Second}: java.lang.NullPointerException
04-25 19:38:19.281: E/AndroidRuntime(1155): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2059)
04-25 19:38:19.281: E/AndroidRuntime(1155): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
04-25 19:38:19.281: E/AndroidRuntime(1155): at android.app.ActivityThread.access$600(ActivityThread.java:130)
04-25 19:38:19.281: E/AndroidRuntime(1155): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
04-25 19:38:19.281: E/AndroidRuntime(1155): at android.os.Handler.dispatchMessage(Handler.java:99)
04-25 19:38:19.281: E/AndroidRuntime(1155): at android.os.Looper.loop(Looper.java:137)
04-25 19:38:19.281: E/AndroidRuntime(1155): at android.app.ActivityThread.main(ActivityThread.java:4745)
04-25 19:38:19.281: E/AndroidRuntime(1155): at java.lang.reflect.Method.invokeNative(Native Method)
04-25 19:38:19.281: E/AndroidRuntime(1155): at java.lang.reflect.Method.invoke(Method.java:511)
04-25 19:38:19.281: E/AndroidRuntime(1155): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
04-25 19:38:19.281: E/AndroidRuntime(1155): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
04-25 19:38:19.281: E/AndroidRuntime(1155): at dalvik.system.NativeStart.main(Native Method)
04-25 19:38:19.281: E/AndroidRuntime(1155): Caused by: java.lang.NullPointerException
04-25 19:38:19.281: E/AndroidRuntime(1155): at com.example.assignment2.Second.onCreate(Second.java:46)
04-25 19:38:19.281: E/AndroidRuntime(1155): at android.app.Activity.performCreate(Activity.java:5008)
04-25 19:38:19.281: E/AndroidRuntime(1155): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079)
04-25 19:38:19.281: E/AndroidRuntime(1155): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2023)
04-25 19:38:19.281: E/AndroidRuntime(1155): ... 11 more
04-25 19:38:19.441: D/dalvikvm(1155): GC_CONCURRENT freed 163K, 3% free 8303K/8519K, paused 79ms+112ms, total 315ms
我相信
basket
是null
。在对其调用put()
之前,需要对其进行初始化
Bundle basket = new Bundle();
了解如何读取日志对于调试您的工作是必不可少的。看看上面的输出
04-25 19:04:11.912: E/AndroidRuntime(999): FATAL EXCEPTION: main
04-25 19:04:11.912: E/AndroidRuntime(999): java.lang.NullPointerException
04-25 19:04:11.912: E/AndroidRuntime(999): at
com.example.assignment2.MainActivity$5.onClick(MainActivity.java:121)
从这里我们可以看到,MainActivity
*编辑**
在Second
中,更改获取额外信息的方式。改变
Intent i = getIntent();//MAking an intent called i
Bundle basket = this.getIntent().getExtras();
到
由于您将捆绑包
放入意图
而不是每个额外的
本身,因此您可以这样做。如果你把每个额外的放在那里,那么你会得到一个捆绑包,就像你现在拥有的那样
(第二个)它可能会更清楚
在您的第一次活动中
更改
intent.putExtras(basket);
到
Logcat或它从未发生过…在MainActivity
的第121行是什么?有些内容为空
therebark.putString(“departureAir”,depAir);不,还是不行。我添加了Bundle basket=新Bundle();就在我之前。把NPE放在同一条线上?有什么不起作用?您是否遇到了不同的错误。这就是导致第一个错误的原因,但可能还有其他问题。当我选择submit按钮时,我收到一条消息“不幸的是,assignment2已停止”,对,仍然存在一个异常,因此您应该有新的logcat输出。检查并查看哪一行显示了NPE
或其他异常
Intent i = getIntent();//MAking an intent called i
Bundle basket = this.getIntent().getExtras();
Intent i = getIntent();//MAking an intent called i
Bundle basket = i.getBundleExtra("basket");
intent.putExtras(basket);
intent.putExtra("basket", basket);