Java 中方法的堆栈索引，示例
原文:https://www . geeksforgeeks . org/stack-indexof-in-method-in-Java-with-example/
Java . util . Stack . indexof(Object element)方法用于检查并查找堆栈中特定元素的出现。如果该元素存在，则返回该元素第一次出现的索引，否则，如果堆栈不包含该元素，则返回-1。
语法:
Stack.indexOf(Object element)
参数:该方法接受堆栈类型的强制参数元素。它指定需要在堆栈中检查其出现的元素。
返回值:该方法返回元素在堆栈中第一次出现的索引或位置。否则，如果元素不在堆栈中，它将返回 -1 。返回值是整数类型。
下面的程序说明了 Java.util.Stack.indexOf()方法:
程序 1:
// Java code to illustrate indexOf()
import java.util.*;
public class StackDemo {
public static void main(String args[])
{
// Creating an empty Stack
Stack<String> stack = new Stack<String>();
// Use add() method to add elements in the Stack
stack.add("Geeks");
stack.add("for");
stack.add("Geeks");
stack.add("10");
stack.add("20");
// Displaying the Stack
System.out.println("Stack: " + stack);
// The first position of an element
// is returned
System.out.println("The first occurrence"
+ " of Geeks is at index:"
+ stack.indexOf("Geeks"));
System.out.println("The first occurrence"
+ " of 10 is at index: "
+ stack.indexOf("10"));
}
}
Output:
Stack: [Geeks, for, Geeks, 10, 20]
The first occurrence of Geeks is at index:0
The first occurrence of 10 is at index: 3
程序 2:
// Java code to illustrate indexOf()
import java.util.*;
public class StackDemo {
public static void main(String args[])
{
// Creating an empty Stack
Stack<Integer> stack = new Stack<Integer>();
// Use add() method to add elements in the Stack
stack.add(1);
stack.add(2);
stack.add(3);
stack.add(10);
stack.add(20);
// Displaying the Stack
System.out.println("Stack: " + stack);
// The first position of an element
// is returned
System.out.println("The first occurrence"
+ " of Geeks is at index:"
+ stack.indexOf(2));
System.out.println("The first occurrence"
+ " of 10 is at index: "
+ stack.indexOf(20));
}
}
Output:
Stack: [1, 2, 3, 10, 20]
The first occurrence of Geeks is at index:1
The first occurrence of 10 is at index: 4
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