java如何写一个方法判断传进来的参数是否数字 java中.怎么写一个判断JTextField是否为空的方法...
java\u5982\u4f55\u5199\u4e00\u4e2a\u65b9\u6cd5\u5224\u65ad\u4f20\u8fdb\u6765\u7684\u53c2\u6570\u662f\u5426\u6570\u5b57\u4e0d\u9700\u8981\u5224\u65ad\uff0c\u56e0\u4e3a\uff1a
\u5728\u5b9a\u4e49\u65b9\u6cd5\u7684\u65f6\u5019\uff0c\u8981\u5b9a\u4e49\u53c2\u6570\u5217\u8868\u91cc\u9762\u7684\u53c2\u6570\u7c7b\u578b\uff0c\u5982\uff1a
public
void
test\uff08
int
num
\uff09{}
\u65e2\u7136\u5df2\u7ecf\u5b9a\u4e49\u597d\u4e86\u53c2\u6570\u7c7b\u578b\uff0c\u5728\u8c03\u7528\u65b9\u6cd5\u7684\u65f6\u5019\uff0c\u5fc5\u987b\u4f20\u5165\u5bf9\u5e94\u7c7b\u578b\u7684\u53c2\u6570\u624d\u80fd\u8c03\u7528\uff0c\u5426\u5219\u4f1a\u8fc7\u4e0d\u4e86\u7f16\u8bd1\u3002
\u7528equals\u5224\u65ad\u5373\u53ef
JTextField aixingwuyue;
aixingwuyue=new JTextField(null);
if(aixingwuyue.getText().trim().equals("")){
//\u7a7a\u7684\u60c5\u51b5\u6267\u884c
}else{
//\u4e0d\u7a7a\u7684\u60c5\u51b5\u6267\u884c
}
Equals\u6bd4\u8f83\u6808\u5185\u5b58\u4e2d\u7684\u5730\u5740\u662f\u5426\u76f8\u7b49 \u3002\u76f8\u7b49\u4e3atrue \u5426\u5219\u4e3afalse\uff1b
Equals\u6bd4\u8f83\u4e24\u4e2a\u503c\u662f\u5426\u76f8\u7b49\u3002\u76f8\u7b49\u4e3atrue \u5426\u5219\u4e3afalse\uff1b
* class名：JudgeIfNumeral
* class说明：java如何写一个方法判断传进来的参数是否数字
* @author Jr
*
*/
public class JudgeIfNumeral {
private static boolean judge(Object obj){
if (obj instanceof Integer) {
return true;
} else if (obj instanceof Double ){
return true;
} else if (obj instanceof Float) {
return true;
//我后加的
} else if(obj instanceof String){
try{
Double.ValueOf(obj.toString.trim());
return true;
}catch(Exception e){
return false;
}
} else {
return false;
}
}
public static void main(String[] args) {
double n = -2.1;
boolean flag = judge(n);
System.out.println(flag);
//我后加的
String str = "-8.34";
System.out.println(judge(str));
}
}
这是楼上给的代码，不过我改了一下加点东西。
这样，即便你吧数字写进字符串里也能判断出来。
如果你不需要字符串判断功能，1楼的回答很好了。
/**
* class名：JudgeIfNumeral
* class说明：java如何写一个方法判断传进来的参数是否数字
* @author Jr
*
*/
public class JudgeIfNumeral {
private static boolean judge(Object obj){
if (obj instanceof Integer) {
return true;
} else if (obj instanceof Double ){
return true;
} else if (obj instanceof Float) {
return true;
} else {
return false;
}
}
public static void main(String[] args) {
double n = -2.1;
boolean flag = judge(n);
System.out.println(flag);
}
}
绛旓細public static void main(String[] args) { double n = -2.1;boolean flag = judge(n);System.out.println(flag);//鎴戝悗鍔犵殑 String str = "-8.34";System.out.println(judge(str));} } 杩欐槸妤间笂缁欑殑浠ｇ爜锛屼笉杩囨垜鏀逛簡涓涓嬪姞鐐逛笢瑗裤傝繖鏍凤紝鍗充究浣犲惂鏁板瓧鍐欒繘瀛楃涓查噷涔熻兘鍒ゆ柇鍑烘潵銆傚鏋...
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绛旓細import java.util.*;public class Test{ public boolean check(){ //涓鐩翠笉鍋滅殑鐩戝惉杈撳叆 while(true){ //閿洏涓婅緭鍏涓涓瀛楃涓 Scanner scanner = new Scanner(System.in);String str = scanner.next();//灏嗗瓧绗︿覆鍙樻垚int绫诲瀷鐨勬暟鎹 int a = Integer.parse(str);//濡傛灉a澶т簬绛変簬0,閭ｄ箞璇存槑鏄...
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