1.在陣列中查詢指定元素
import java.util.ArrayList;

public class Main {
public static void main(String[] args) {
ArrayList objArray = new ArrayList();
ArrayList objArray2 = new ArrayList();
objArray2.add(0,"common1");
objArray2.add(1,"common2");
objArray2.add(2,"notcommon");
objArray2.add(3,"notcommon1");
objArray.add(0,"common1");
objArray.add(1,"common2");
System.out.println("objArray 的陣列元素："+objArray);
System.out.println("objArray2 的陣列元素："+objArray2);
System.out.println("objArray 是否包含字串common2? ： "
+objArray.contains("common2"));
System.out.println("objArray2 是否包含陣列 objArray? ："
+objArray2.contains(objArray) );
}
}
/objArray 的陣列元素：[common1, common2]
objArray2 的陣列元素：[common1, common2, notcommon, notcommon1]
objArray 是否包含字串common2? ： true
objArray2 是否包含陣列 objArray? ：false

public class Main {
public static void main(String[] args) throws Exception {
int[] ary = {1,2,3,4,5,6};
int[] ary1 = {1,2,3,4,5,6};
int[] ary2 = {1,2,3,4};
System.out.println("陣列 ary 是否與陣列 ary1相等? ："
+Arrays.equals(ary, ary1));
System.out.println("陣列 ary 是否與陣列 ary2相等? ："
+Arrays.equals(ary, ary2));
}
}
3.陣列並集
import java.util.Arrays;
import java.util.HashSet;
import java.util.Set;

public class Main {
public static void main(String[] args) throws Exception {
String[] arr1 = { "1", "2", "3" };
String[] arr2 = { "4", "5", "6" };
String[] result_union = union(arr1, arr2);
System.out.println("並集的結果如下：");

    for (String str : result_union) {
        System.out.println(str);
    }
}

// 求兩個字串陣列的並集，利用set的元素唯一性
public static String[] union(String[] arr1, String[] arr2) {
    Set<String> set = new HashSet<String>();

    for (String str : arr1) {
        set.add(str);
    }

    for (String str : arr2) {
        set.add(str);
    }
    String[] result = {  };
    return set.toArray(result);
}
 

}