Question

在java中如何对比输入的字符串

import java.io.*;
class GameHelper {
public String getUserInput(String prompt) {
String inputLine = null;
System.out.print(prompt + " ");
try {
BufferedReader is = new BufferedReader(new InputStreamReader(System.in));
inputLine = is.readLine();
if (inputLine.length() == 0)
return null;
} catch (Exception e) {
System.out.println("IOException: " + e);
}
return inputLine;
}
}
public class SizeUp {
public static void main (String[] arges) {
GameHelper helper = new GameHelper();
String input = helper.getUserInput("entrer a command");
if ( input == "-yes" )
System.out.println("yes");
else System.out.println("no");
}
}

我是希望能判断输入的命令，从而做对应的动作。这里只是简单的输入“-yes”能显示“yes”。可现在不断输入是什么，打印出来的都是“no”，这是为什么？是不是像C一样，输入的字符串结束都会有个“/0”？那如果要实现我的功能，要如何修改？希望有高手能对我进行指点，谢谢

Answer 1

java中字符串的比较用的是equals方法。
代码修改如下：
import java.io.*;
class GameHelper {
public String getUserInput(String prompt) {
String inputLine = null;
System.out.print(prompt + " ");
try {
BufferedReader is = new BufferedReader(new InputStreamReader(System.in));
inputLine = is.readLine();
if (inputLine.length() == 0)
return null;
} catch (Exception e) {
System.out.println("IOException: " + e);
}
return inputLine;
}
}
public class Demo {
public static void main (String[] arges) {
GameHelper helper = new GameHelper();
String input = helper.getUserInput("entrer a command");
if ( input.equals("-yes"))
System.out.println("yes");
else System.out.println("no");
}
}
只需将input == "-yes"改为input.equals("-yes")就行了，字符串型的比较不是用==，是用equals，int型和float型等的比较才能使用==来比较。

Answer 2

import java.io.*;

class GameHelper
{
public String getUserInput(String prompt)
{
String inputLine = null;
System.out.print(prompt + " ");
try
{
BufferedReader is = new BufferedReader(new InputStreamReader(
System.in));
inputLine = is.readLine();
if (inputLine.length() == 0)
return null;
} catch (Exception e)
{
System.out.println("IOException: " + e);
}
return inputLine;
}
}

public class SizeUp
{
public static void main(String[] arges)
{
GameHelper helper = new GameHelper();
String input = helper.getUserInput("entrer a command");
if (input.equals("-yes"))
System.out.println("yes");
else
System.out.println("no");
}
}

改为:input.equals("-yes")) 这是比较内容的
==是比较对象的

Answer 3

==只能用来比较八大基本类型
字符串一般都是String型的 要比较应该用equals方法
你这个应该改成
if(input.equals("-yes")){
System.out.println("yes");
}else {
System.out.println("no");
}

给你个建议java代码最好把括号加好 要不等报错时就难找了