通用方法語法

Question

我忘記了泛型方法的語法：

public static void swap <T> (T a, T b)
{...}

我找不到任何一個例子。什么是正確的語法？

Answer 1

Here I have written a sample piece which i have used for my application. You can get an idea from this.


        public <C>void addColumn(Cell<C> cell, String headerText,
              final GetValue<C> getter, FieldUpdater<DocumentType, C> fieldUpdater) {
            Column<DocumentType, C> column = new Column<DocumentType, C>(cell) {
              @Override
              public C getValue(DocumentType object) {
                return getter.getValue(object);
              }
            };
            column.setFieldUpdater(fieldUpdater);
            column.setHorizontalAlignment(HasHorizontalAlignment.ALIGN_CENTER);
            getTable().addColumn(column, headerText);
            getTable().setColumnWidth(column, 10, Unit.PX);
    }

Answer 2

static <T> void swap(T a, T b) {..}

Answer 3

您必須在返回類型之前聲明您鍵入的參數（在您的情況下為void）。

http://docs.oracle.com/javase/specs/jls/se5.0/html/classes.html#8.4 （參見TypeParameters ）