我用 5 个方法用 Java 编写了一个类。线性搜索，如果找到值则返回 true，如果未找到则返回 false。线性搜索 2，如果找到，则返回值的位置。二进制搜索。它也在数组中搜索值，打印 Int 数组，它一次打印 10 个数字，以及选择排序，它对数组进行排序，以便我可以进行二进制搜索。一切都编译得很好，但由于某种原因，我的方法都没有返回任何东西（除了 void printIntArray 方法）。
编辑：
谢谢，伙计们，我没有意识到我需要那个。出于某种原因，我认为它会自行返回值……不过，这是另一个问题。binarySearch 方法似乎没有做任何事情。在打印语句“使用二进制搜索在随机数组中搜索 11”之后......，没有打印任何内容。
编辑 2：我的 binarySearch 方法不起作用，因为我不小心为两个 else 语句设置了 mid + 1（else if (key < array[mid]) 应该是 mid - 1）。非常感谢大家！我添加了修复程序。
public class sortingSearching {
public static boolean linearSearch (int [] array, int key) {
for (int i = 0; i < array.length; i++) {
if (array [i] == key)
return true;
}// end for
return false;
}
public static int linearSearch2 (int [] array, int key) {
for (int i = 0; i < array.length; i++) {
if (array [i] == key)
return i;
}//end for
return -1;
}//end linearSearch2
public static boolean binarySearch (int [] array, int key) {
int left = 0;
int right = array.length - 1;
int mid = (left + right) /2;
while (left <= right) {
if (array[mid] == key)
return true;
else if ( key < array[mid])
right = mid - 1;
else
left = mid + 1;
mid = (left + right) /2;
} //end while
return false;
}//end binarySearch
public static void printIntArray (int [] array) {
for (int i = 0; i < array.length; i++) {
if (i%10 == 0)
System.out.println();
System.out.print(array[i] + " ");
} // end for
}
public static void selectionSort (int [] array) {
for (int start = 0; start < array.length - 1; start ++) {
int minI = start;
for (int i = start + 1; i < array.length; i++)
if (array[i] < array[start])
minI = i;
int temp = array[start];
array[start] = array[minI];
array[minI] = temp;
}//end for
} //end selectionSort
public static void main (String args []) {
int [] array = new int [20];
for (int i =0; i < array.length; i++)
array[i] = (int)((Math.random() * 100) + 1);
//print the array using printArray
printIntArray(array);
System.out.println();
//use linearSearch to search for 30, 86, and 87
System.out.println("Searching for 30 in the random array. If true is returned, " +
"the value was found. If false was returned, the value was not found.");
System.out.println(linearSearch(array, 30));
System.out.println("Searching for 86 in the random array. If true is returned, " +
"the value was found. If false was returned, the value was not found.");
System.out.println(linearSearch(array, 86));
System.out.println("Searching for 87 in the random array. If true is returned, " +
"the value was found. If false was returned, the value was not found.");
System.out.println(linearSearch(array, 87));
//use linearSearch to locate the first occurrences of 25, 80, and 91
System.out.println("Searching for the location of 25 in the random array. If -1 is " +
"returned, the number was not found in the array.");
System.out.println(linearSearch2(array, 25));
System.out.println("Searching for the location of 80 in the random array. If -1 is " +
"returned, the number was not found in the array.");
System.out.println(linearSearch2(array, 80));
System.out.println("Searching for the location of 91 in the random array. If -1 is " +
"returned, the number was not found in the array.");
System.out.println(linearSearch2(array, 91));
//use selectionSort to sort the array
selectionSort(array);
//use binarySearch to search for 11, 28, 74, and 99
System.out.println("Searching for 11 in the random array using binary search. If true is returned, " +
"the value was found. If false was returned, the value was not found.");
System.out.println(binarySearch (array, 11));
System.out.println("Searching for 28 in the random array using binary search. If true is returned, " +
"the value was found. If false was returned, the value was not found.");
System.out.println(binarySearch (array, 28));
System.out.println("Searching for 74 in the random array using binary search. If true is returned, " +
"the value was found. If false was returned, the value was not found.");
System.out.println(binarySearch (array, 74));
System.out.println("Searching for 99 in the random array using binary search. If true is returned, " +
"the value was found. If false was returned, the value was not found.");
System.out.println(binarySearch (array, 99));
} //end main
} //end sortingSearching
另外，很抱歉 main 方法中的所有打印语句都分散了注意力。我想把它们拿出来以方便阅读，但我希望它和我一直在运行它一样。