优秀程序员都在注意的十个点

public boolean isInValid(String str) {
    if (str == null || str.trim().length() == 0) {
        return true;
    }
    return false;
}
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public boolean isInValid(String str) {
  return (str == null) || (str.trim().length() == 0);
}
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public boolean isEmptyName() {
    return StringUtils.isEmpty(name)? true: false;
}
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public boolean isEmptyName() {
    return StringUtils.isEmpty(name);
}
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public static SearchFilter name(String name) {
    return human -> human.getName().equalsIgnoreCase(name);
}
public Human find(SearchFilter filter) {
    for (Human human : humans) {
        if (filter.isMatched(human)) {
            return human;
        }
    }
    return new NullHuman();   //如果你返回NULL，总有一天你会挨骂！
}
//Test
assertFalse(edu.find(name("steven")).isNull());
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public enum EquipmentEnum {
    Staff(20), Hammer(10);
    double playerRisedAbility;
    EquipmentEnum(double playerRiseAbility) {
        this.playerRisedAbility = playerRiseAbility;
    }
    public double getRaiseAbility(double originalAbility) {
        return Double.sum(originalAbility, playerRisedAbility);
    }
}
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public class Customer {
    Benefiter benefit = new NullBenefiter();
    public void is(Benefiter benefits) { //原本的set方法，重命名会带来意想不到的效果。
        this.benefit = benefits;
    }
    public double shouldPay(double srcPrice) {
        return srcPrice - benefit.benefit(srcPrice);
    }
}
@FunctionalInterface
public interface Benefiter {
    abstract double benefit(double srcPrice);
    default Benefiter and(final Benefiter otherPolicy) {
        return srcPrice -> (benefit(srcPrice) + otherPolicy.benefit(srcPrice));
    }
}
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public class ExchangeRate {
    public static final int DOLLAR = 0;
    public static final int FRANC = 1;
    public static final int YMB = 2;
    private static final double[][] rates = {   //二维数组定义币种之间的汇率，简单高效
            {1.0d, 2.0d, 8.0d},
            {0.5d, 1.0d, 4.0d},
            {0.125d, 0.25d, 1.0d}
    };
    public static double getRateOf(Currency src, Currency tgt) {
        return rates[src.ID][tgt.ID];
    }
}
public class Cash {
    private double value;
    private Currency unit;
    public Cash(double value, Currency unit) {
        this.value = value;
        this.unit = unit;
    }
    @Override
    public boolean equals(Object obj) {
        if (obj instanceof Cash) {
            Cash other = (Cash) obj;
            return value == other.value * getRateOf(other.unit, unit);
        }
        return false;
    }
}
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public static double getRateOf(Currency src, Currency tgt) {
  return rates[src.ID][tgt.ID];
}
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public static double getRateOf(int src, int tgt) {
  return rates[src][tgt];
}
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public class CollectionUtil {
    public static boolean isEmpty(Collection collection) {
        return collection == null || collection.isEmpty();
    }
}
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public class StringUtil {
    public static boolean isEmpty(String context) {
        return context == null || context.isEmpty();
    }
}
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public String say(int input) throws Exception {
    if ( input < 1 || input > 1000){
        throw new Exception("Invalid input");
    }
    if (input % 15 == 0) {
        return "FIZZBUZZ";
    }
    if (input % 5 == 0) {
        return "BUZZ";
    }
    if (input % 3 == 0) {
        return "FIZZ";
    }
    return String.valueOf(input);
}
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public String say(int input) throws Exception {
    if (input < 1 || input > 1000) {
        throw new Exception("Invalid input");
    }
    DefaultParser defaultParser = new DefaultParser(null);
    MultiOfThreeParser multiOfThreeParser = new MultiOfThreeParser(defaultParser);
    MultiOfFiveParser multiFiveParser = new MultiOfFiveParser(multiOfThreeParser);
    MultiOfFifteenParser fifteenPaser = new MultiOfFifteenParser(multiFiveParser);
    return fifteenPaser.parse(input);
}
public abstract class Parser {
    abstract boolean isFixedResponsibility(int inputContext);
    abstract String response(int inputContext) throws Exception;
    public String parse(int inputContext) throws Exception  {
        if (isFixedResponsibility(inputContext))     {
            return response(inputContext);
        }
        if (nextParser != null) {
            return nextParser.parse(inputContext);
        }
        return NULL;
    }
}
public class MultiOfFifteenParser extends Parser {
    public MultiOfFifteenParser(Parser nextParser) {
        super(nextParser);
    }
    @Override
    public String response(int inputContext) throws Exception {
        return FLAG_FOR_MULIT_OF_FIFTEEN;
    }
    @Override
    boolean isFixedResponsibility(int inputContext)    {
        return inputContext % 15 == 0;
    }    
}
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public String say(int input) throws Exception {
    DefaultParser defaultParser = new DefaultParser(null);
    MultiOfThreeParser multiOfThreeParser = new MultiOfThreeParser(defaultParser);
    MultiOfFiveParser multiOfFiveParser = new MultiOfFiveParser(multiOfThreeParser);
    MultiOfFifteenParser FifteenPaser = new MultiOfFifteenParser(multiOfFiveParser);
    InvalidNumberParser invalidNumberPaser = new InvalidNumberParser(FifteenPaser);
    return invalidNumberPaser.parse(input);
}
public class InvalidNumberParser extends Parser {
    public InvalidNumberParser(Parser nextParser) {
        super(nextParser);
    }
    @Override
    String response(int inputContext) throws Exception {
        throw new Exception("Invalid input");
    }
    @Override
    boolean isFixedResponsibility(int inputContext){
        return (inputContext < L_THRESHOLD) || (inputContext > H_THRESHOLD);
    }
}
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