前端代码

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <EditText
        android:id="@+id/et_1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:inputType="phone"
        android:hint="请输入年份" />

    <EditText
        android:id="@+id/et_2"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:inputType="phone"
        android:hint="请输入月份" />

    <Button
        android:id="@+id/but_1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:onClick="onClickButton"
        android:text="查询" />

    <TextView
        android:id="@+id/tv_1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:text="查询结果"
        android:textSize="30sp" />
</LinearLayout>

后端代码

package com.example.comzhaoshijidays;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {


    private EditText Et_month;
    private EditText Et_year;
    private TextView Vt_show;
    int int_yer;
    int int_mon;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Et_month = findViewById(R.id.et_2);
        Et_year = findViewById(R.id.et_1);
        Vt_show = findViewById(R.id.tv_1);
    }

    public static int Year(int i) {
        int c;

        if ((i % 4 == 0 && i % 100 != 0) || (i % 400 == 0)) {
            c = 1;
            return c = 1;
        } else {
            return c = 0;
        }
    }

    public void onClickButton(View view) {

        String str_year = Et_year.getText().toString();
        int_yer = Year(Integer.parseInt(str_year));
        int_mon = Month(Integer.parseInt(Et_month.getText().toString()));
        if (int_yer == 1) {
            Vt_show.setText(Et_year.getText().toString() + "年" + "是润年" + "," + Et_month.getText().toString() + "月共有" + int_mon + "天");
        } else {
            Vt_show.setText(Et_year.getText().toString() + "年" + "是平年" + "," + Et_month.getText().toString() + "月共有" + int_mon + "天");
        }

    }

    private int Month(int i) {
        int day = 0;
        switch (i) {
            case 1:
            case 3:
            case 5:
            case 7:
            case 8:
            case 10:
            case 12:
                day = 31;
                break;
            case 4:
            case 6:
            case 9:
            case 11:
                day = 30;
                break;
            default:
                if (int_yer == 1) {
                    day = 29;
                } else {
                    day = 28;
                }

        }
        return day;
    }
}