我在使用GridAdapter for Andorid gridview时出现问题。错误是“12-28 21：35：44.893：E / AndroidRuntime（370）：java.lang.RuntimeException：无法启动活动ComponentInfo {btn.grid / btn.grid.ButtonGridActivity}：java.lang.ArrayIndexOutOfBoundsException “
并且适配器是
package btn.grid;
import android.content.Context;
import android.graphics.Color;
import android.util.DisplayMetrics;
import android.view.Gravity;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.GregorianCalendar;
import java.util.List;
class MonthAdapter extends BaseAdapter {
private GregorianCalendar mCalendar;
private Calendar mCalendarToday;
private Context mContext;
private DisplayMetrics mDisplayMetrics;
private List<String> mItems;
private int mMonth;
private int mYear;
private int mDaysShown;
private int mDaysLastMonth;
private int mDaysNextMonth;
private int mTitleHeight, mDayHeight;
private final String[] mDays = { "Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun" };
private final int[] mDaysInMonth = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
public MonthAdapter(Context c, int month, int year ) {
mContext = c;
mMonth = month;
mYear = year;
mCalendar = new GregorianCalendar(mYear, mMonth, 1);
mCalendarToday = Calendar.getInstance();
populateMonth();
}
private void populateMonth() {
mItems = new ArrayList<String>();
for (String day : mDays) {
mItems.add(day);
mDaysShown++;
}
int firstDay = getDay(mCalendar.get(Calendar.DAY_OF_WEEK));
int prevDay;
if (mMonth == 0)
prevDay = daysInMonth(11) - firstDay + 1;
else
prevDay = daysInMonth(mMonth - 1) - firstDay + 1;
for (int i = 0; i < firstDay; i++) {
mItems.add(String.valueOf(prevDay + i));
mDaysLastMonth++;
mDaysShown++;
}
int daysInMonth = daysInMonth(mMonth);
for (int i = 1; i <= daysInMonth; i++) {
mItems.add(String.valueOf(i));
mDaysShown++;
}
mDaysNextMonth = 1;
while (mDaysShown % 7 != 0) {
mItems.add(String.valueOf(mDaysNextMonth));
mDaysShown++;
mDaysNextMonth++;
}
mTitleHeight = 30;
int rows = (mDaysShown / 7);
mDayHeight = (mDisplayMetrics.heightPixels - mTitleHeight
- (rows * 3) - getBarHeight())/ (rows - 1);
}
private int daysInMonth(int month) {
int daysInMonth = mDaysInMonth[month];
if (month == 1 && mCalendar.isLeapYear(mYear))
daysInMonth++;
return daysInMonth;
}
private int getBarHeight() {
switch (mDisplayMetrics.densityDpi) {
case DisplayMetrics.DENSITY_HIGH:
return 48;
case DisplayMetrics.DENSITY_MEDIUM:
return 32;
case DisplayMetrics.DENSITY_LOW:
return 24;
default:
return 48;
}
}
/**
* For week starting Monday
* @param day from Calendar.DAY_OF_WEEK
* @return day week starting Monday
*/
private int getDay(int day) {
switch (day) {
case Calendar.MONDAY:
return 0;
case Calendar.TUESDAY:
return 1;
case Calendar.WEDNESDAY:
return 2;
case Calendar.THURSDAY:
return 3;
case Calendar.FRIDAY:
return 4;
case Calendar.SATURDAY:
return 5;
case Calendar.SUNDAY:
return 6;
default:
return 0;
}
}
private boolean isToday(int day, int month, int year) {
if (mCalendarToday.get(Calendar.MONTH) == month
&& mCalendarToday.get(Calendar.YEAR) == year
&& mCalendarToday.get(Calendar.DAY_OF_MONTH) == day) {
return true;
}
return false;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
final TextView view = new TextView(mContext);
view.setGravity(Gravity.CENTER_VERTICAL | Gravity.CENTER_HORIZONTAL);
view.setText(mItems.get(position));
view.setBackgroundColor(Color.rgb(244, 244, 244));
view.setTextColor(Color.BLACK);
if (position <= 6) {
// names
view.setBackgroundColor(Color.argb(100, 10, 80, 255));
view.setHeight(mTitleHeight);
} else if (position <= mDaysLastMonth + 6) {
// previous month
view.setBackgroundColor(Color.rgb(234, 234, 245));
view.setHeight(mDayHeight);
} else if (position <= mDaysShown - mDaysNextMonth ) {
// current month
view.setHeight(mDayHeight);
int day = position - (mDaysLastMonth + 6);
if (isToday(day, mMonth, mYear)) {
view.setTextColor(Color.RED);
}
// check db and colour for shifts
// ...
} else {
// next month
view.setHeight(mDayHeight);
view.setBackgroundColor(Color.rgb(234, 234, 245));
}
return view;
}
@Override
public int getCount() {
return mItems.size();
}
@Override
public Object getItem(int position) {
return mItems.get(position);
}
@Override
public long getItemId(int position) {
return position;
}
}
* logcat的
12-28 21:35:44.873: W/dalvikvm(370): threadid=1: thread exiting with uncaught exception (group=0x40015560)
12-28 21:35:44.893: E/AndroidRuntime(370): FATAL EXCEPTION: main
12-28 21:35:44.893: E/AndroidRuntime(370): java.lang.RuntimeException: Unable to start activity ComponentInfo{btn.grid/btn.grid.ButtonGridActivity}: java.lang.ArrayIndexOutOfBoundsException
12-28 21:35:44.893: E/AndroidRuntime(370): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647)
12-28 21:35:44.893: E/AndroidRuntime(370): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
12-28 21:35:44.893: E/AndroidRuntime(370): at android.app.ActivityThread.access$1500(ActivityThread.java:117)
12-28 21:35:44.893: E/AndroidRuntime(370): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
12-28 21:35:44.893: E/AndroidRuntime(370): at android.os.Handler.dispatchMessage(Handler.java:99)
12-28 21:35:44.893: E/AndroidRuntime(370): at android.os.Looper.loop(Looper.java:123)
12-28 21:35:44.893: E/AndroidRuntime(370): at android.app.ActivityThread.main(ActivityThread.java:3683)
12-28 21:35:44.893: E/AndroidRuntime(370): at java.lang.reflect.Method.invokeNative(Native Method)
12-28 21:35:44.893: E/AndroidRuntime(370): at java.lang.reflect.Method.invoke(Method.java:507)
12-28 21:35:44.893: E/AndroidRuntime(370): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
12-28 21:35:44.893: E/AndroidRuntime(370): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
12-28 21:35:44.893: E/AndroidRuntime(370): at dalvik.system.NativeStart.main(Native Method)
12-28 21:35:44.893: E/AndroidRuntime(370): Caused by: java.lang.ArrayIndexOutOfBoundsException
12-28 21:35:44.893: E/AndroidRuntime(370): at btn.grid.MonthAdapter.daysInMonth(MonthAdapter.java:82)
12-28 21:35:44.893: E/AndroidRuntime(370): at btn.grid.MonthAdapter.populateMonth(MonthAdapter.java:62)
12-28 21:35:44.893: E/AndroidRuntime(370): at btn.grid.MonthAdapter.<init>(MonthAdapter.java:40)
12-28 21:35:44.893: E/AndroidRuntime(370): at btn.grid.ButtonGridActivity.onCreate(ButtonGridActivity.java:16)
12-28 21:35:44.893: E/AndroidRuntime(370): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
12-28 21:35:44.893: E/AndroidRuntime(370): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
12-28 21:35:44.893: E/AndroidRuntime(370): ... 11 more
答案 0 :(得分：0)
从你添加的stracktrace中，你可以看到ArrayIndexOutOfBoundsException来自第82行。这意味着以下结果是例外：
int daysInMonth = mDaysInMonth[month];
换句话说，mDaysInMonth中的查找使用了无效索引;可能month > 11虽然也可能是负面的。
month是您传递给的参数：
private int daysInMonth(int month)
对此方法的调用导致异常来自第62行：
int daysInMonth = daysInMonth(mMonth);
这意味着mMonth是最终数组查找的无效索引。由于mMonth是在适配器的构造函数中初始化的，因此您最好在创建MonthAdapter时检查传递它的值。
public MonthAdapter(Context c, int month, int year ) {
(...)
mMonth = month;
(...)
}