Java 检索给定月份一周的第一天

给定此代码，它将打印出正确的月份和年份，但似乎会显示通常不正确的随机日期。我已经看过一些链接，包括和

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您可能应该使用

Calendar.DAY\u OF_WEEK

而不是

Calendar.DAY\u OF_WEEK\u IN_MONTH

public void dayOfTheWeek() {
    now.set(Calendar.YEAR, year);
    now.set(Calendar.MONTH, month);
    now.set(Calendar.DAY_OF_MONTH, 1);

    String[] strDays = new String[] {
      "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"
    };
    JOptionPane.showMessageDialog(null, year);
    JOptionPane.showMessageDialog(null, monthString[month - 1]);
    JOptionPane.showMessageDialog(null, now.get(Calendar.DAY_OF_WEEK));
    JOptionPane.showMessageDialog(null, strDays[now.get(Calendar.DAY_OF_WEEK) -     1]);
  }

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假设您有正确的

月份

和

年份

，您可以这样做：

now.set(Calendar.DATE, 1);
now.set(Calendar.MONTH, month);
now.set(Calendar.YEAR, year);
int dayOfWeek = now.get(Calendar.DAY_OF_WEEK);

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更改设置顺序，设置月后的月日，不设置月内的周日。

now.set(Calendar.DATE, 1);
now.set(Calendar.MONTH, month);
now.set(Calendar.YEAR, year);
int dayOfWeek = now.get(Calendar.DAY_OF_WEEK);