运行java实例6

1.删除数组元素
Java 的数组是固定长度的，无法直接删除，我们可以通过创建一个新数组，把原始数组中要保留的元素放到新数组中即可：
import java.util.Arrays;

public class RunoobTest {

public static void main(String[] args) {
    int[] oldarray = new int[] {3, 4, 5, 6, 7};// 原始数组
    int num = 2;   // 删除索引为 2 的元素，即删除第三个元素 5
    int[] newArray = new int[oldarray.length-1];// 新数组，长度为原始数组减去 1
    
    for(int i=0;i<newArray.length; i++) {
        // 判断元素是否越界
        if (num < 0 || num >= oldarray.length) {
            throw new RuntimeException("元素越界... "); 
        } 
        // 
        if(i<num) {
            newArray[i] = oldarray[i];
        }
        else {
            newArray[i] = oldarray[i+1];//跳过要删除的那个元素
        }
    }
    // 打印输出数组内容
    System.out.println(Arrays.toString(oldarray));
    oldarray = newArray;
    System.out.println(Arrays.toString(oldarray));
}

}
2.数组差集
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");
objArray.add(2,"notcommon2");
System.out.println("array1 的元素" +objArray);
System.out.println("array2 的元素" +objArray2);
objArray.removeAll(objArray2);//差集
System.out.println("array1 与 array2 数组差集为："+objArray);
}
}
3.数组交集
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");
objArray.add(2,"notcommon2");
System.out.println("array1 数组元素："+objArray);
System.out.println("array2 数组元素："+objArray2);
objArray.retainAll(objArray2);//交集
System.out.println("array2 & array1 数组交集为："+objArray);
}
}