数组

数组

这里有一些代码有空的话可以琢磨一下

public class Test1 {


/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
//数组声明时，数组长度是常量
int length = 6;
int[] ages = new int[length];//定义数组的时候，6为数组的长度,代表能放多少个元素

int[] scores = {0,20,-150,6,'c'};

//数组使用时，下标可以是变量
for(int i = 0; i < 6; i++){
ages[i] = 100;
}
//数组的最大下标是长度-1
// ages[6] = 300;//会报数组下标越界异常
System.out.println(scores[4]);

}

import java.util.Scanner;


public class Test2 {


/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner scan = new Scanner(System.in);
//数据类型   变量名
int[] scores = new int[6];
for(int i = 0; i < 6; i++){
System.out.println("请输入第" + (i + 1) + "位同学的成绩：");
scores[i] = scan.nextInt();
}

for(int i = 0; i < 6; i++){
if(scores[i] >= 80){
System.out.println("A");
}else if(scores[i] >= 60){
System.out.println("B");
}else{
System.out.println("C");
}
}


}


}

import java.util.Scanner;


public class Test3 {


/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner scan = new Scanner(System.in);
System.out.println("请输入你要操作的学生人数：");
int num = scan.nextInt();

int[] scores = new int[num];

for(int i = 0; i < num; i++){
System.out.println("请输入第" + (i + 1) + "位同学的成绩：");
scores[i] = scan.nextInt();
}

double allScores = 0;
for(int i = 0; i < num; i++){
allScores += scores[i];
}

double avg = allScores / num;
System.out.println("平均分是：" + avg);

}


}

import java.util.Scanner;




public class Test4 {


/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner scan = new Scanner(System.in);
int[] scores = new int[6];

for(int i = 0; i < 6; i++){
System.out.println("请输入第" + (i + 1) + "个学生的成绩：");
scores[i] = scan.nextInt();
}

int maxScore = scores[0];
int maxIndex = 0;

for(int i = 1; i < 6; i++){
if(scores[i] > maxScore){
maxScore = scores[i];
maxIndex = i;
}
}

System.out.println("最高分是：" + maxScore);
System.out.println("他(她)是第" + (maxIndex + 1) + "个同学。");


}


}

import java.util.Scanner;


public class Test5 {


/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
int[] array = {12,23,34,45,56,67,78,89,90};
Scanner scan = new Scanner(System.in);
System.out.println("请输入一个数字：");
int num = scan.nextInt();

//使用 数组名.length可以得到数组长度
boolean flag = false;
for(int i = 0; i < array.length; i++){
if(num == array[i]){
System.out.println("该数字在数组中存在！");
flag = true;
break;
}
}

if(!flag){
System.out.println("该数字在数组中不存在！");
}


}


}

import java.util.Scanner;


public class Test6 {


/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
int[] array = {12,23,34,45,56,67,78,89,90};
Scanner scan = new Scanner(System.in);
System.out.println("请输入一个数字：");
int num = scan.nextInt();

int[] newArray = new int[array.length + 1];
for(int i = 0; i < 9; i++){
newArray[i] = array[i];
}

newArray[array.length] = num;

//打印结果
for(int i = 0; i < newArray.length; i++){
System.out.println(newArray[i]);
}

}


}

import java.util.Scanner;


public class Test7 {


/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
int[] array = {12,23,34,45,56,67,78,89,90};

Scanner scan = new Scanner(System.in);
System.out.println("请输入一个数字：");
int num = scan.nextInt();

int[] newArray = new int[array.length + 1];
for(int i = 0; i < array.length; i++){
newArray[i] = array[i];
}

int index = array.length;//初始化的时候把index设置为最后一个元素！
for(int i = 0; i < array.length; i++){
if(array[i] > num){
index = i;
break;
}
}


for(int i = newArray.length - 1; i >= index + 1; i--){
newArray[i] = newArray[i - 1];
}

newArray[index] = num;

//打印
for(int i = 0; i < newArray.length; i++){
System.out.println(newArray[i]);
}



}


}

import java.util.Scanner;


public class Test8 {


/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
int[] array = { 12, 23, 34, 45, 56, 67, 78, 89, 90 };


Scanner scan = new Scanner(System.in);
System.out.println("请输入一个数字：");
int num = scan.nextInt();

int index = -1;
for(int i = 0; i < array.length; i++){
if(num == array[i]){
index = i;
break;
}
}

if(index != -1){
for(int i = index; i < array.length - 1; i++){
array[i] = array[i + 1];
}

array[array.length - 1] = 0;

//打印
for(int i = 0; i < array.length; i++){
System.out.println(array[i]);
}

}else{
System.out.println("该数字不在数组中！");
}

}


}

import java.util.Scanner;


public class Test9 {


/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub

// String str = "hello";
// char[] array = str.toCharArray();//将一个字符串转换成char数组的方法
//
// for(int i = 0; i < array.length; i++){
// System.out.println(array[i]);
// }

Scanner scan = new Scanner(System.in);
System.out.println("请输入第一个字符串：");
String str1 = scan.next();
System.out.println("请输入第二个字符串：");
String str2 = scan.next();

char[] array1 = str1.toCharArray();
char[] array2 = str2.toCharArray();

char[] array3 = new char[array1.length + array2.length];

for(int i = 0; i < array1.length; i++){
array3[i] = array1[i];
}

for(int i = 0; i < array2.length; i++){
array3[array1.length + i] = array2[i];
}

//打印
for(int i = 0; i < array3.length; i++){
System.out.print(array3[i]);
}
}


}

import java.util.Scanner;


public class Test10 {


/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub

int[][] arrays = new int[5][6];
int[][] arrays2 = {{1,2,3},{5,6,7,8,5},{9,10,11,12}};

int[][][] arrays3 = new int[3][3][3];

String[] strArray = new String[5];//字符串的一维数组，相当于char的二维数组



// Scanner scan = new Scanner(System.in);
//
// for(int i = 0; i < 5; i++){
// for(int j = 0; j < 6; j++){
// System.out.println("请输入第" + (i + 1) + "组的第" + (j + 1) + "位同学的成绩：");
// arrays[i][j] = scan.nextInt();
// }
//
// }

}


}