Java BigDecimal、Integer、Long、Double类型数值累加求和

小灰灰 2022-10-31 04:08 561阅读 0赞

## 1 BigDecimal类型数值累加求和 ##

### 1.1 for循环实现 ###

List<BigDecimal> list=new ArrayList<>();
    BigDecimal sum=new BigDecimal(0);
    for(BigDecimal decimal:list){
        sum=sum.add(decimal);
    }

### 1.2 stream().reduce()实现 ###

List<BigDecimal> list=new ArrayList<>();
    BigDecimal sum=list.stream().reduce(0,BigDecimal::add);

## 2 Integer类型数值累加求和 ##

### 2.1 for循环实现 ###

List<Integer> list=new ArrayList<>();
    Integer sum=0;
    for(Integer i:list){
        sum+=i;
    }

### 2.2 stream().reduce()实现 ###

List<Integer> list=new ArrayList<>();
    //lambda表达式实现
    Integer sum = list.stream().reduce(0, (current, number) -> current + number);
    //方法引用实现
    Integer sum2 = list.stream().reduce(0, Integer::sum);

### 2.3 Collectors.summingInt()实现 ###

List<Integer> list=new ArrayList<>();
    long sum = list.stream().collect(Collectors.summingInt(x -> x));

### 2.4 Collectors.summarizingInt()实现 ###

List<Integer> list = new ArrayList<>();
            IntSummaryStatistics summaryStatistics = list.stream().collect(Collectors.summarizingInt(x -> x));
            long sum = summaryStatistics.getSum();

## 3**Long****类型数值累加求和** ##

### 3.1 for循环实现 ###

List<Long> list=new ArrayList<>();
    Long sum=0L;
    for(Long i:list){
        sum+=i;
    }

### 3.2 stream().reduce()实现 ###

List<Long> list=new ArrayList<>();
    //lambda表达式实现
    Long sum = list.stream().reduce(0L, (current, number) -> current + number);
    //方法引用实现
    Long sum2 = list.stream().reduce(0L, Long::sum);

### 3.3 Collectors.summingLong()实现 ###

List<Long> list=new ArrayList<>();
    long sum = list.stream().collect(Collectors.summingLong(x -> x));

### 3.4 Collectors.summarizingInt()实现  ###

List<Long> list = new ArrayList<>();
            LongSummaryStatistics summaryStatistics = list.stream().collect(Collectors.summarizingLong(x -> x));
            long sum = summaryStatistics.getSum();

## 4 Double类型数值累加求和 ##

### 4.1 for循环实现 ###

List<Double> list = new ArrayList<>();
    Double sum = 0d;
    for (Double i : list) {
        sum += i;
    }

### 3.2 stream().reduce()实现 ###

List<Double> list=new ArrayList<>();
    //lambda表达式实现
    Double sum = list.stream().reduce(0d, (current, number) -> current + number);
    //方法引用实现
    Double sum2 = list.stream().reduce(0d, Double::sum);

### 3.3 Collectors.summingDouble()实现 ###

List<Double> list=new ArrayList<>();
    Double sum = list.stream().collect(Collectors.summingDouble(x -> x));

### 3.5 Collectors.summarizingDouble()实现  ###

List<Double> list = new ArrayList<>();
            DoubleSummaryStatistics summaryStatistics = list.stream().collect(Collectors.summarizingDouble(x -> x));
            double sum = summaryStatistics.getSum();