Java List Implementation with Search, Insert, and Remove

Java List Implementation

Class Definition

public class Lista { 
    private Object[] item;
    private int primeiro, ultimo, pos;

    public Lista(int maxTam) {
        this.item = new Object[maxTam];
        this.pos = -1;
        this.primeiro = 0;
        this.ultimo = this.primeiro;
    }
}

Search Method

public Object pesquisa(Object chave) {
    if (this.vazia() || chave == null) {
        return null;
    }
    for (int p = 0; p < this.ultimo; p++) {
        if (this.item[p].equals(chave)) {
            return this.item[p];
        }
    }
    return null;
}

Insert Method

public void insere(Object x) {
    if (this.ultimo >= this.item.length) {
        throw new Exception("Error: List is full");
    } else {
        this.item[this.ultimo] = x;
        this.ultimo++;
    }
}

Remove Method

public Object retira(Object chave) {
    if (this.vazia() || chave == null) {
        throw new Exception("Error: List is empty");
    }
    int p = 0;
    while (p < this.ultimo && !this.item[p].equals(chave)) {
        p++;
    }
    if (p >= this.ultimo) {
        return null; // Key not found
    }
    Object item = this.item[p];
    this.ultimo--;
    for (int aux = p; aux < this.ultimo; aux++) {
        this.item[aux] = this.item[aux + 1];
    }
    return item;
}

Remove First Method

public Object retiraPrimeiro() {
    if (this.vazia()) {
        throw new Exception("Error: List is empty");
    }
    Object item = this.item[0];
    this.ultimo--;
    for (int aux = 0; aux < this.ultimo; aux++) {
        this.item[aux] = this.item[aux + 1];
    }
    return item;
}

First and Next Methods

public Object primeiro() {
    this.pos = -1;
    return this.proximo();
}

public Object proximo() {
    this.pos++;
    if (this.pos >= this.ultimo) {
        return null;
    } else {
        return this.item[this.pos];
    }
}

Empty and Print Methods

public boolean vazia() {
    return (this.primeiro == this.ultimo);
}

public void imprime() {
    for (int aux = this.primeiro; aux < this.ultimo; aux++) {
        System.out.print(this.item[aux].toString() + " ");
    }
}