java取list前⼗对象_Java通过stream（）获取到List（列
表）中最⼩的对象元素
class Foo {
private int variableCount;
public Foo(int vars) {
this.variableCount = vars;
}
public Integer getVariableCount() {
java streamreturn variableCount;
}
}
1、实现accumulator object⽤于给Collector提供函数/**
* Accumulator object to hold the current min
* and the list of Foos that are the min.
*/
class Accumulator {
Integer min;
List foos;
Accumulator() {
min = Integer.MAX_VALUE;
foos = new ArrayList<>();
}
void accumulate(Foo f) {
if (f.getVariableCount() != null) {
if (f.getVariableCount() < min) {
min = f.getVariableCount();
foos.clear();
foos.add(f);
} else if (f.getVariableCount() == min) {
foos.add(f);
}
}
}
Accumulator combine(Accumulator other) {
if (min < other.min) {
return this;
}
else if (min > other.min) {
return other;
}
else {
foos.addAll(other.foos);
return this;
}
}
List getFoos() { return foos; }
}
2、调⽤⽅法和测试
1)⽰例ListList foos = Arrays.asList(new Foo(3), new Foo(3), new Foo(2), new Foo(1), new Foo(1), new Foo(4));
2)调⽤⽅法List mins = foos.stream().collect(Collector.of(
Accumulator::new,
Accumulator::accumulate,
Accumulator::combine,
Accumulator::getFoos
)
);
输出结果：
[Foo{1}, Foo{1}]

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