java基础练习题(含答案)[通俗易懂]

 int oldArr[] = { 1, 3, 4, 5, 0, 0, 6, 6, 0, 5, 4, 7, 6, 7, 0, 5 };
        int count = 0;
        for (int i = 0; i < oldArr.length; i++) {
            if (oldArr[i] != 0) {
                count++;
            }
        }
        int[] newArr = new int[count];
        int a=0;
        for (int i = 0; i <oldArr.length; i++) {
            if (oldArr[i] != 0) {
                newArr[a]=oldArr[i];
                a++;
            }
        }
        System.out.println(Arrays.toString(newArr));
        for(int n:newArr) {
            System.out.print(n+" ");
        }

public static void main(String[] args) {
int[] a= {1,7,9,11,13,15,17,19};
		int[] b= {2,4,6,8,10};
		int[] c= new int[a.length+b.length];
		System.arraycopy(a, 0, c, 0, a.length);
		System.arraycopy(b, 0, c, a.length, b.length);
		Arrays.sort(c);//给数组c进行升序拍序，Arrays.sort()是Arrays类的静态方法，可以直接拿来使用
		System.out.println(Arrays.toString(c));
 	}

}

package work;public class Person {    private String name;    private Integer age;    @Override    public String toString() {        return "Person{" +                "name='" + name + '\'' +                ", age=" + age +                '}';    }    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    public Integer getAge() {        return age;    }    public void setAge(Integer age) {        this.age = age;    }    public Person(String name, Integer age) {        this.name = name;        this.age = age;    }}

package work;public class MainClass {    public void person(){        Person person=new Person("张三",21);        person.display();    }    public static void main(String[] args) {        MainClass mainClass=new MainClass();        mainClass.person();    }}

package work;//(1)定义一个类WuMingFen（无名的粉）public class WuMingFen {    //(2)该类有三个属性：粉名:String name; 粉的分量(两)：int quantity ;是否带汤：boolean likeSoup    private String name;    private  int quantity;    private boolean likeSoup;    //（3）构造方法1：含三个参数，为三个属性赋值。    public WuMingFen(String name, int quantity, boolean likeSoup) {        this.name = name;        this.quantity = quantity;        this.likeSoup = likeSoup;    }    //（4）构造方法2：含两个参数，为前两个属性赋值    public WuMingFen(String name, int quantity) {        this.name = name;        this.quantity = quantity;    }    //（5）构造方法3：不含参数的构造方法，完成属性的初始化为：.粉名：酸辣面；分量：2两；是否带汤：带汤。    public WuMingFen() {        name="酸辣粉";        quantity=2;        likeSoup=true;    }    //(6）写一个普通方法：String check()，方法的功能：用字符串连接符连接该类的三个属性并返回一个字符串，例如：“牛肉粉、2两、不带汤”。    public String check(){        return name+quantity+likeSoup;    }    public static void main(String[] args) {    //（7）定义一个主类，分别调用类WuMingFen的3个构造方法完成3个对象的创建，并调用check方法，输出其方法的返回值。        WuMingFen wuMingFen1=new WuMingFen("牛肉粉",1,true);        WuMingFen wuMingFen2=new WuMingFen("羊肉汤",2);        WuMingFen wuMingFen3=new WuMingFen();        wuMingFen1.check();        wuMingFen2.check();        wuMingFen3.check();        System.out.println(wuMingFen1.check());        System.out.println(wuMingFen2.check());        System.out.println(wuMingFen3.check());    }}

class Student {

public Student() {

System.out.println("无参的构造方法");

}

public Student(String name) {

this();

System.out.println("一个参数的构造方法");

}

public Student(String name, int age) {

this(name);

System.out.println("两个参数的构造方法");

}

}

public class Example06 {

public static void main(String[] args) {

Student s1 = new Student("Jack", 22);

}

}

无参的构造方法
一个参数的构造方法
两个参数的构造方法

package work;

public class FamilyPerson {
    private String surname;
    private String name;

    public void setSurname(String surname) {
        this.surname = surname;
    }

    public void setName(String name) {
        this.name = name;
    }

    @Override
    public String toString() {
        return surname+name;
    }
}

package work;

public class MainClass {
    static String surname;
    public static void main(String[] args) {
        //1.实例化三个对象，一个父亲father，一个大儿子sonone，一个二儿子sontwo
        FamilyPerson father=new FamilyPerson();
        FamilyPerson sonone=new FamilyPerson();
        FamilyPerson sontwo=new FamilyPerson();
        //2.调用setSurname为姓赋值（例如：张、李、王）
        father.setSurname("张");
        sonone.setSurname("李");
        sontwo.setSurname("王");
        //3.调用setName为三个对象的名赋值
        father.setName("爸爸");
        sonone.setName("明明");
        sontwo.setName("天天");
        //4.显示三个对象的姓名
        System.out.println(father);
        System.out.println(sonone);
        System.out.println(sontwo);
        //5. 调用setSurname给父亲、大儿子、二儿子改姓
        surname="赵";
        father.setSurname(surname);
        sonone.setSurname(surname);
        sontwo.setSurname(surname);
        //6.再次显示三个对象的姓名
        System.out.println(father);
        System.out.println(sonone);
        System.out.println(sontwo);
    }

}

package work;

public class Tank {
    protected double speed;
    protected int bulletAmount;
    protected char color;

    public void speedUp(int x) {
        this.speed = x;
        speed++;
        if (x > 200) {
            System.out.println("最高时速不能超过200公里/小时！");
            speed--;
        }
        System.out.println("速度为：" + x);
    }

    public void speedDown(int x) {
        this.speed = x;
        speed--;

    }

    public void setBulletAmount(int x) {
        this.bulletAmount = x;

    }

    public double getSpeed() {
        return speed;

    }

    public int getBulletAmount() {
        return bulletAmount;

    }

    public void fire() {
        bulletAmount--;

    }

    public void conFire(int x) {
        this.bulletAmount = x;
        if (x > 0) {
            x--;
        }
    }

    public void setColor(char x) {
        this.color = x;
    }

    public char getColor() {
        return color;
    }

    public void brake() {
        speed = 0;

    }
}

package work;

public class Fight {

    public static void main(String[] args) {
        Tank t1=new Tank();
        Tank t2=new Tank();
        t1.speedUp(300);
        t1.speedUp(188);
        t1.setBulletAmount(10);
        t1.setBulletAmount(12);
        t1.setColor('绿');
        t1.fire();
        t1.speedDown(150);
        t2.setColor('黄');
        t2.conFire(12);
        if(t1.bulletAmount>0){
            t1.brake();
        }
        if(t2.bulletAmount>0){
            t2.brake();
        }
        System.out.print(t1.speed);
        System.out.println(t1.color);
        System.out.println(t2.color);
        System.out.print(t2.speed);
    }

}