Parse the commonly used methods in the List interface that are overridden by subclasses

解析ListThe commonly used in the interface is implemented subclasses override method

1 在index位置插入element元素

1.1 使用方法

List接口的实现子类.add(int index,Object element);
//返回值类型为void,The original set ofindexLocation and its elements will be moving back after a

1.2 示例代码

package Work;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
public class Test07 {
    
    public static void main(String[] args) {
    
        List arr = new ArrayList();
        arr.add("12");
        arr.add("66");
        arr.add("77");
        Iterator iterator = arr.iterator();
        while (iterator.hasNext()) {
    
            Object next =iterator.next();
            System.out.println(next);
        }
        System.out.println("在下标为1的位置插入字符串55后");
        arr.add(1,"55");
        //使用for循环进行遍历
        for (int i = 0; i < arr.size(); i++) {
    
            System.out.println(arr.get(i));
        }
    }
}

1.3 示例代码运行截图

2 从indexPosition began to set all the elements of inside added

2.1 使用方法

CollectionThe realization of the collection of child.addAll(int index,Collection c);
//返回值类型为布尔类型,As long as add successful elements,就返回true
//indexLocation and its later elements need to move backc集合的size()

2.2 示例代码

package Work;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
public class Test07 {
    
    public static void main(String[] args) {
    
        List arr = new ArrayList();
        arr.add("12");
        arr.add("66");
        arr.add("77");
        Iterator iterator = arr.iterator();
        System.out.println("添加之前");
        while (iterator.hasNext()) {
    
            Object next =iterator.next();
            System.out.println(next);
        }
        ArrayList arrayList=new ArrayList();
        arrayList.add("88");
        arrayList.add("22");
        System.out.println("添加之后");
        arr.addAll(1,arrayList);
        //使用for循环进行遍历
        for (int i = 0; i < arr.size(); i++) {
    
            System.out.println(arr.get(i));
        }
    }
}

2.3 示例代码运行截图

3 获取指定index位置的元素

3.1 使用方法

Collection接口的实现子类.get(int index);
//返回值为Object对象,Return you find object,If there is no subscript will throw an exception

3.2 示例代码

package Work;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
public class Test07 {
    
    public static void main(String[] args) {
    
        List arr = new ArrayList();
        arr.add("12");
        arr.add("66");
        arr.add("77");
        System.out.println("indexThe subscript position exists");
        System.out.println(arr.get(0));
        System.out.println("indexThe subscript position does not exist");
        //Throws the subscript cross-border exception the runtime exception,在控制台打印错误信息,程序中断,At the back of the statement is not to
        System.out.println(arr.get(arr.size()));
        System.out.println("后面的语句");
    }
}

3.3 示例代码运行截图

4 返回objThe position of the object in the collection for the first time in

4.1 使用方法

ListThe realization of the interface under the subclass.indexOf(Object obj);
//返回值类型为int类型,与String类中的indexOfThe analogy memory
//If found no placeObject对象时,会返回-1,Found it returns the corresponding index

4.2 示例代码

package Work;
import java.util.ArrayList;
import java.util.List;
public class Test07 {
    
    public static void main(String[] args) {
    
        List arr = new ArrayList();
        arr.add("12");
        arr.add("66");
        arr.add("77");
        System.out.println("存在Object对象时");
        System.out.println(arr.indexOf("12"));
        System.out.println("不存在Object对象时");
        System.out.println(arr.indexOf("88"));
    }
}

4.3 示例代码运行截图

5 返回objObjects in the position of the first occurrence in the current set(从后往前)

5.1 使用方法

List接口的实现子类.lastIndexOf(Object o);
//返回值为int类型,从后往前找,If for the first time found in the collection andoThe content of the content of the object as,That is returned in the collection the subscript,If the traverse through hasn't found,就返回-1

5.2 示例代码

package Work;
import java.util.ArrayList;
import java.util.List;
public class Test07 {
    
    public static void main(String[] args) {
    
        List arr = new ArrayList();
        arr.add("12");
        arr.add("66");
        arr.add("77");
        System.out.println("存在Object对象时");
        System.out.println(arr.lastIndexOf("12"));
        System.out.println("不存在Object对象时");
        System.out.println(arr.lastIndexOf("88"));
    }
}

5.3 示例代码运行截图

6 移除指定index位置的元素

6.1 使用方法

List接口的实现子类.remove(int index);
//返回值为Object对象(Returns to the delete the location element),Because we want to know the subscript to delete what things

6.2 示例代码

package Work;
import java.util.ArrayList;
import java.util.List;
public class Test07 {
    
    public static void main(String[] args) {
    
        List arr = new ArrayList();
        arr.add("12");
        arr.add("66");
        arr.add("77");
        System.out.println("删除前");
        for (Object temp01:
             arr) {
    
            System.out.println(temp01);
        }
        //因为String类重写了toString方法,所以可以直接打印
        System.out.println("Delete the elements as:"+arr.remove(1));
        System.out.println("删除后");
        for (Object temp02:
                arr) {
    
            System.out.println(temp02);
        }
    }
}

6.3 示例代码运行截图

7 设置指定index位置的元素为element(替换)

7.1 使用方法

List接口的实现子类.set(int index,Object element);
//返回值为Object对象,Back to be replaced element object,We want to know who is be replaced

7.2 示例代码

package Work;
import java.util.ArrayList;
import java.util.List;
public class Test07 {
    
    public static void main(String[] args) {
    
        List arr = new ArrayList();
        arr.add("12");
        arr.add("66");
        arr.add("77");
        System.out.println("替换前");
        for (Object temp01:
             arr) {
    
            System.out.println(temp01);
        }
        //因为String类重写了toString方法,所以可以直接打印
        System.out.println("The contents of a element is replaced as:"+arr.set(1,"99"));
        System.out.println("替换后");
        for (Object temp02:
                arr) {
    
            System.out.println(temp02);
        }
    }
}

7.3 示例代码运行截图

8 返回从fromIndex位置到toIndexBefore a the location set

8.1 使用方法

List接口的实现子类.subList(int index,Object element);
//返回值为List结合,Get a is a collection of,The collection will not change,类似于String类里面的subString方法
//如果下标不在范围内,会出现下标越界异常

8.2 示例代码

package Work;
import java.util.ArrayList;
import java.util.List;
public class Test07 {
    
    public static void main(String[] args) {
    
        List arr1 = new ArrayList();
        arr1.add("12");
        arr1.add("66");
        arr1.add("77");
        List arr2=arr1.subList(0,2);
        System.out.println("Intercept the child after collection content is as follows:");
        for (int i = 0; i <arr2.size();i++) {
    
            System.out.println(arr2.get(i));
        }
    }
}

8.3 示例代码运行截图