I am a rookie: the creation of java sequence table

package sqlist;

public class TestSqList {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
    SqList p1=new SqList();
    for(int i=0;i<9;i++){
        p1.insert_data(i,i);
    }
    p1.show();
    System.out.println("___________________");
    p1.insert_data(100,5);
    p1.show();
    System.out.println("___________________");
    System.out.println(p1.search_soyin(100));
    System.out.println("___________________");
    p1.delete(100);
    p1.show();
    }

}
class SqList{
    int usedsize;
    int [] elem;
    public SqList(){
        this (10);
    }
    public SqList(int size){
        elem = new  int [size]; // Define an array with a length of size 
        usedsize=0 ;
    }
    public void show(){
        for(int i=0;i<usedsize;i++){
            System.out.println("elem:"+elem[i]);
        }
        System.out.println();
    }
    
    // Insert a data into the sequence table, so first judge whether the sequence table is full 
    public  boolean isFull(){
         if (usedsize== elem.length){
             return  true ;
        }
        return false;
    }
    public boolean insert_data(int val,int pos){
        if(isFull()){
            return false;
        }
        if(pos<0||pos>usedsize){
            return false;
        }
        for ( int i=usedsize-1;i>=pos;i-- ){
             /* -1 is considering that the first position of the array is 0, and the last index of valid data is exactly the number of valid data -1
            Because the number of data starts from 1, the index starts from 0 */ 
            elem[i +1]= elem[i];
        }
        element [pos] = val;
        usedsize++;
        return true;
    }
    // Check whether the current sequence table is empty before querying 
    public  boolean isEmpty(){
         if (usedsize==0 ){
             return  true ;
        }
        return false;
    }
    // Find a data key in the sequence table and return its subscript 
    public  int search_soyin( int key){
         for ( int i=0;i<usedsize;i++ ){
             if (elem[i]== key){
                 return i;
            }
        }return -1;
        
    }
    public boolean delete( int key){
        
        int Index = search_soyin(key);
        if(Index<0){
            return false;
        }
        for(int i=Index;i<usedsize-1;i++){
            element [i] = element [i + 1 ];
        }
        usedsize--;
        return true;
    }
}   

items: 0 
items: 1 
items: 2 
items: 3 
items: 4 
items: 5 
items: 6 
items: 7 
items: 8

___________________
items: 0 
items: 1 
items: 2 
items: 3 
items: 4 
items: 100 
items: 5 
items: 6 
items: 7 
items: 8

___________________
5
___________________
items: 0 
items: 1 
items: 2 
items: 3 
items: 4 
items: 5 
items: 6 
items: 7 
items: 8

 

package sqlist;
public class TestSqList {
public static void main(String[] args) {// TODO Auto-generated method stub    SqList p1=new SqList();    for(int i=0;i<9;i++){    p1.insert_data(i,i);    }    p1.show();    System.out.println("___________________");    p1.insert_data(100,5);    p1.show();    System.out.println("___________________");    System.out.println(p1.search_soyin(100));    System.out.println("___________________");    p1.delete(100);    p1.show();}
}class SqList{int usedsize;int [] elem;public SqList(){this (10);}public SqList(int size){elem=new int[size];//Define an array of length size usedsize=0 ;}public void show(){for(int i=0;i<usedsize;i++){System.out.println("elem:"+elem[i]);}System.out.println();}/ /Insert a data into the sequence table, so first judge whether the sequence table is full public boolean isFull(){if(usedsize==elem.length){return true;}return false;}public boolean insert_data(int val,int pos){if(isFull()){return false;}if(pos<0||pos>usedsize){return false;}for( int i=usedsize-1;i>=pos;i--){/ *-1 is considering that the first bit of the array is 0, and the last index of valid data is just the number of valid data -1 because the number of data starts from 1, and the index starts from 0 */elem[i+1]=elem[ i];}elem[pos]=val;usedsize++;return true;}//Check whether the current sequence table is empty before querying public boolean isEmpty(){if(usedsize==0){return true;} return false;}//Find a data key in the sequence table and return its subscript public int search_soyin(int key){for(int i=0;i<usedsize;i++){if(elem[i]= =key){return i;}}return -1;}public boolean delete( int key){int Index = search_soyin(key);if(Index<0){return false;}for(int i=Index;i<usedsize-1;i++){elem[i]=elem[i+1];}usedsize--;return true;}}