Android - 显示Int on单击按钮递增，递减 [错误：无法解析方法“显示（int）” ]

Question

Android - 显示Int上点击按钮递增 ，递减 [错误：无法解析方法'显示（int）' ] 我在Android Studio上收到错误，因为我认为是因为我正在插入多个“显示器”。有人可以建议吗

请查看以下错误:

package com.example.justjava;

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

import androidx.appcompat.app.AppCompatActivity;

import java.text.NumberFormat;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        TextView num = findViewById(R.id.num);
        Button order1 = findViewById(R.id.order);
        /**
         * This method is called when the plus button is clicked.
         */
        public void increment (View view) {
            int quantity = 2;
            display(quantity);
        }
        /**
         * This method is called when the minus button is clicked.
         */
        public void onClick (View view) {
            int quantity = 2;
            display(quantity);
        }


        /**
         * This method is called when the order button is clicked.
         */
        order1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                int quantity = 2;
                display1(quantity);
                displayPrice(quantity*5);
            }

            /**
             * This method displays the given price on the screen.
             */
            private void displayPrice(int number) {
                TextView priceTextView = (TextView) findViewById(R.id.price_text_view);
                priceTextView.setText(NumberFormat.getCurrencyInstance().format(number));
            }
            /**
             * This method displays the given quantity value on the screen.
             */
            private void display1(int number)
            {
                //  TextView quantity = (TextView) findViewById(R.id.quantity);
                num.setText("" + number);
            }


        });
    }
}

Answer 1

在Java中，我们没有任何称为局部函数的东西，因此，将函数从onCreate方法移到类中。