java - 无法在 Eclipse 中解析 R.menu

Question

我刚开始研究 Android Development Tutorial on youtube .我在执行CrazyTipCalc.java 时，Eclipse 报如下错误:

menu cannot be resolved or is not a field   CrazyTipCalc.java   /CrazyTipCalc/src/com/example/crazytipcalc  line 107    Java Problem

以下是CrazyTipCalc.java的代码，其中最后6行出现了“R.menu not resolved”的问题。我在构建项目之前导入了 com.example.crazytipcalc.R。为什么会出现此问题以及如何解决？谢谢。

package com.example.crazytipcalc;

import android.app.Activity;
import android.os.Bundle;
import android.text.Editable;
import android.text.TextWatcher;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.EditText;
import android.widget.SeekBar;
import android.widget.SeekBar.OnSeekBarChangeListener;
import com.example.crazytipcalc.R;
//import android.R;

public class CrazyTipCalc extends Activity {
    public static final String TOTAL_BILL = "Total bill";
    public static final String CURRENT_TIP = "Current tip";
    public static final String BILL_WITHOUT_TIP = "Bill without tip";

    private double billBeforeTip;
    private double tipAmount;
    private double finalBill;

    EditText billBeforeTipET;
    EditText tipAmountET;
    EditText finalBillET;

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

        if(savedInstanceState == null) {
            billBeforeTip = 0.0;
            tipAmount = .15;
            finalBill = 0.0;        
        } else {

            billBeforeTip = savedInstanceState.getDouble(BILL_WITHOUT_TIP);
            tipAmount = savedInstanceState.getDouble(CURRENT_TIP);
            finalBill = savedInstanceState.getDouble(TOTAL_BILL);
        }

        billBeforeTipET = (EditText) findViewById(R.id.billEditText);
        tipAmountET = (EditText) findViewById(R.id.tipEditText);
        finalBillET = (EditText) findViewById(R.id.finalBillEditText);

        tipSeekBar = (SeekBar) findViewById(R.id.changeTipSeekBar);
        tipSeekBar.setOnSeekBarChangeListener(tipSeekBarListener);

        billBeforeTipET.addTextChangedListener(billBeforeTipListener);
    }
        private TextWatcher billBeforeTipListener = new TextWatcher() {

            @Override
            public void afterTextChanged(Editable arg0) {}
            public void beforeTextChanged(CharSequence arg0, int arg1, int arg2, int arg3) {}
            public void onTextChanged(CharSequence arg0, int arg1, int arg2, int arg3) {
                try{
                    //Change the billBeforeTip to the new input 
                    billBeforeTip = Double.parseDouble(arg0.toString());
                }
                catch(NumberFormatException e) {
                    billBeforeTip = 0.0;

                }
                updateTipAndFinalBill();
            }
        };
    private void updateTipAndFinalBill() {

        double tipAmount = Double.parseDouble(tipAmountET.getText().toString());
        double finalBill = billBeforeTip + (billBeforeTip * tipAmount);
        finalBillET.setText(String.format("%.02f", finalBill));
    }
    protected void onSaveInstanceState(Bundle outState) {

        super.onSaveInstanceState(outState);

        outState.putDouble(TOTAL_BILL, finalBill);
        outState.putDouble(CURRENT_TIP, tipAmount);
        outState.putDouble(BILL_WITHOUT_TIP, billBeforeTip);   
    }
    //End of first part
    //Second Part

    //SeekBar used to make a custom tip

    private SeekBar tipSeekBar;

    private OnSeekBarChangeListener tipSeekBarListener = new OnSeekBarChangeListener(){

        @Override
        public void onProgressChanged(SeekBar arg0, int arg1, boolean arg2) {
            tipAmount = (tipSeekBar.getProgress()) * 0.01;
            tipAmountET.setText(String.format("%.02f", tipAmount));
            updateTipAndFinalBill();
        }
        @Override
        public void onStartTrackingTouch(SeekBar arg0) {}

        public void onStopTrackingtouch(SeekBar arg0) {}
    };
    //End of second part
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.crazy_tip_calc, menu);
        return true;
    }
}

Answer 1

检查 res/menu 文件夹中是否有 crazy_tip_calc.xml。

在此之后，尝试一个项目>clean