「javaequal源码」Java源码
今天给各位分享javaequal源码的知识，其中也会对Java源码进行解释，如果能碰巧解决你现在面临的问题，别忘了关注本站，现在开始吧！
本文目录一览：
- 1、在java中e.getActionCommand()和e.getLabel()是什么意思？有什么区别?还有e.equal()和e.getSource()???
- 2、急求JAVA计算器源代码
- 3、求编写一个超级简单的Java的程序源代码
- 4、关于java String类的substring()和equals()方法
在java中e.getActionCommand()和e.getLabel()是什么意思？有什么区别?还有e.equal()和e.getSource()???
getActionCommand()和getLabel（）都是返回按钮的命令名或者说标签名，不同的是getActionConmand()在接口方法actionPerformed重定义调用，而getLabel（）在任何地方都可以使用。equals（）用来进行比较，不同的类会有不同返回值，e。getSource（）返回引发该事件的那个事件源也就是那个组件。
急求JAVA计算器源代码
//HTML
html
applet code=SZJSQ.class width=400 height=180
/applet
/html
//APPLET
import java.util.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.applet.*;
public class SZJSQ extends JApplet implements ActionListener
{
boolean i=true;
private JButton num0=new JButton("0");
private JButton num1=new JButton("1");
private JButton num2=new JButton("2");
private JButton num3=new JButton("3");
private JButton num4=new JButton("4");
private JButton num5=new JButton("5");
private JButton num6=new JButton("6");
private JButton num7=new JButton("7");
private JButton num8=new JButton("8");
private JButton num9=new JButton("9");
private JButton zuok=new JButton("(");
private JButton youk=new JButton(")");
private JButton dian=new JButton(".");
private JButton NULL=new JButton("N");
private JButton plu=new JButton("+");
private JButton min=new JButton("-");
private JButton mul=new JButton("x");
private JButton div=new JButton("/");
private JButton equ=new JButton("=");
private JButton cle=new JButton("C");//清除
private JTextField space=new JTextField(30);
public void init()
{
JPanel text=new JPanel();
text.setLayout(new FlowLayout());
text.add(space);
JPanel buttons=new JPanel();
buttons.setLayout(new GridLayout(5,4));
buttons.add(num9);
buttons.add(num8);
buttons.add(num7);
buttons.add(plu);
buttons.add(num6);
buttons.add(num5);
buttons.add(num4);
buttons.add(min);
buttons.add(num3);
buttons.add(num2);
buttons.add(num1);
buttons.add(mul);
buttons.add(num0);
buttons.add(cle);
buttons.add(equ);
buttons.add(div);
buttons.add(zuok);
buttons.add(youk);
buttons.add(dian);
buttons.add(NULL);
(num9).addActionListener(this);
(num8).addActionListener(this);
(num7).addActionListener(this);
(num6).addActionListener(this);
(num5).addActionListener(this);
(num4).addActionListener(this);
(num3).addActionListener(this);
(num2).addActionListener(this);
(num1).addActionListener(this);
(num0).addActionListener(this);
(plu).addActionListener(this);
(min).addActionListener(this);
(mul).addActionListener(this);
(div).addActionListener(this);
(equ).addActionListener(this);
(cle).addActionListener(this);
(zuok).addActionListener(this);
(youk).addActionListener(this);
(dian).addActionListener(this);
setLayout(new BorderLayout());
add("North",text);
add("South",buttons);
space.setText("0");
}
public void actionPerformed(ActionEvent e)
{
if(e.getSource()==num9)
{
if(i==true)
{
space.setText("9");
i=false;
}
else space.setText(space.getText()+'9');
}
if(e.getSource()==num8)
{
if(i==true)
{
space.setText("8");
i=false;
}
else space.setText(space.getText()+'8');
}
if(e.getSource()==num7)
{
if(i==true)
{
space.setText("7");
i=false;
}
else space.setText(space.getText()+'7');
}
if(e.getSource()==num6)
{
if(i==true)
{
space.setText("6");
i=false;
}
else space.setText(space.getText()+'6');
}
if(e.getSource()==num5)
{
if(i==true)
{
space.setText("5");
i=false;
}
else space.setText(space.getText()+'5');
}
if(e.getSource()==num4)
{
if(i==true)
{
space.setText("4");
i=false;
}
else space.setText(space.getText()+'4');
}
if(e.getSource()==num3)
{
if(i==true)
{
space.setText("3");
i=false;
}
else space.setText(space.getText()+'3');
}
if(e.getSource()==num2)
{
if(i==true)
{
space.setText("2");
i=false;
}
else space.setText(space.getText()+'2');
}
if(e.getSource()==num1)
{
if(i==true)
{
space.setText("1");
i=false;
}
else space.setText(space.getText()+'1');
}
if(e.getSource()==num0)
{
if(i==true)
{
space.setText("0");
i=false;
}
else space.setText(space.getText()+'0');
}
if(e.getSource()==zuok)
{
if(i==true)
{
space.setText("(");
i=false;
}
else space.setText(space.getText()+'(');
} if(e.getSource()==youk)
{
if(i==false)
space.setText(space.getText()+')');
}
if(e.getSource()==dian)
{
if(i==false)
space.setText(space.getText()+'.');
}
if(e.getSource()==plu)
{
space.setText(space.getText()+'+');
i=false;
}
if(e.getSource()==min)
{
space.setText(space.getText()+'-');
i=false;
}
if(e.getSource()==mul)
{
space.setText(space.getText()+'*');
i=false;
}
if(e.getSource()==div)
{
space.setText(space.getText()+'/');
i=false;
}
if(e.getSource()==equ)
{
space.setText(String.valueOf(Calculator(space.getText())));
i=true;
}
if(e.getSource()==cle)
{
space.setText("0");
i=true;
}
}
public double Calculator(String f)//科学计算
{
int i=0,j=0,k;
char c;
StringBuffer s=new StringBuffer();
s.append(f);
s.append('=');
String formula=s.toString();
char[] anArray;
anArray=new char[50];
StackCharacter mystack=new StackCharacter();
while(formula.charAt(i)!='=')
{
c=formula.charAt(i);
switch(c)
{
case '(': mystack.push(new Character(c));
i++;
break;
case ')':
while(mystack.peek().charValue()!='(')
{
anArray[j++]=mystack.pop().charValue();
}
mystack.pop();
i++;
break;
case '+':
case '-':
while(!mystack.empty()mystack.peek().charValue()!='(')
{
anArray[j++]=mystack.pop().charValue();
}
mystack.push(new Character(c));
i++;
break;
case '*':
case '/':
while(!mystack.empty()(mystack.peek().charValue()=='*'||mystack.peek().charValue()=='/'))
{
anArray[j++]=mystack.pop().charValue();
}
mystack.push(new Character(c));
i++;
break;
case' ': i++;
break;
default: while((c='0'c='9')||c=='.')
{
anArray[j++]=c;
i++;
c=formula.charAt(i);
}
anArray[j++]='#';
break;
}
}
while(!(mystack.empty()))
anArray[j++]=mystack.pop().charValue();
i=0;
int count;
double a,b,d;
StackDouble mystack1 =new StackDouble();
while(ij)
{
c=anArray[i];
switch(c)
{
case '+':
a=mystack1.pop().doubleValue();
b=mystack1.pop().doubleValue();
d=b+a;
mystack1.push(new Double(d));
i++;
break;
case '-':
a=mystack1.pop().doubleValue();
b=mystack1.pop().doubleValue();
d=b-a;
mystack1.push(new Double(d));
i++;
break;
case '*':
a=mystack1.pop().doubleValue();
b=mystack1.pop().doubleValue();
d=b*a;
mystack1.push(new Double(d));
i++;
break;
case '/':
a=mystack1.pop().doubleValue();
b=mystack1.pop().doubleValue();
if(a!=0)
{
d=b/a;
mystack1.push(new Double(d));
i++;
}
else
{
System.out.println("Error!");
}
break;
default:
d=0;count=0;
while((c='0'c='9'))
{
d=10*d+c-'0';
i++;
c=anArray[i];
}
if(c=='.')
{
i++;
c=anArray[i];
while((c='0'c='9'))
{
count++;
d=d+(c-'0')/Math.pow(10,count);
i++;
c=anArray[i];
}
}
if(c=='#')
mystack1.push(new Double(d));
i++;
break;
}
}
return(mystack1.peek().doubleValue());
}
}
求编写一个超级简单的Java的程序源代码
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
class ConstructFrame extends JFrame
{
private static final long serialVersionUID = 1L;
String value1="",result,value2="";
int flag=0,fix=0,sum=1;
Boolean happy;
JTextField text=new JTextField(30);
int flagsum=0;
Container c=getContentPane();
JButton buttonx;
ConstructFrame()
{ super("计算器");
c.setLayout(null);
c.setBackground(Color.blue);
this.setSize(400, 400);
c.add(text);
text.setHorizontalAlignment(JTextField.RIGHT);
final JButton buttonx=new JButton("BackSpace");
c.add(buttonx);
buttonx.addMouseListener(new MouseAdapter()
{
public void mousePressed(MouseEvent e)
{
int count=0;
String temp;
if(flag==0)
{
count=value1.length();
if(count!=1)
temp=value1.substring(0, count-1);
else
temp="0";
value1=temp;
}
else
{
count=value2.length();
if(count!=1)
temp=value2.substring(0, count-1);
else
temp="0";
value2=temp;
}
text.setText(temp);
}
});
final JButton buttony=new JButton("CE");
c.add(buttony);
buttony.addMouseListener(new MouseAdapter()
{
public void mousePressed(MouseEvent e)
{
value1="";
value2="";
flag=0;
text.setText("0");
}
});
final JButton button1=new JButton("1");
c.add(button1);
button1.addMouseListener(new MouseAdapter()
{
public void mousePressed(MouseEvent e)
{
String temp;
if(flag==0)
{
value1=value1+1;
temp=value1;
}
else
{
value2=value2+1;
temp=value2;
}
text.setText(temp);
}
});
final JButton button2=new JButton(" 2 ");
c.add(button2);
button2.addMouseListener(new MouseAdapter()
{
public void mousePressed(MouseEvent e)
{
String temp;
if(flag==0)
{
value1=value1+2;
temp=value1;
}
else
{
value2=value2+2;
temp=value2;
}
text.setText(temp);
}
});
final JButton button3=new JButton("3");
c.add(button3);
button3.addMouseListener(new MouseAdapter()
{
public void mousePressed(MouseEvent e)
{
String temp;
if(flag==0)
{
value1=value1+3;
temp=value1;
}
else
{
value2=value2+3;
temp=value2;
}
text.setText(temp);
}
});
final JButton button4=new JButton("4");
c.add(button4);
button4.addMouseListener(new MouseAdapter()
{
public void mousePressed(MouseEvent e)
{
String temp;
if(flag==0)
{
value1=value1+4;
temp=value1;
}
else
{
value2=value2+4;
temp=value2;
}
text.setText(temp);
}
});
final JButton button5=new JButton("5");
c.add(button5);
button5.addMouseListener(new MouseAdapter()
{
public void mousePressed(MouseEvent e)
{
String temp;
if(flag==0)
{
value1=value1+5;
temp=value1;
}
else
{
value2=value2+5;
temp=value2;
}
text.setText(temp);
}
});
final JButton button6=new JButton("6");
c.add(button6);
button6.addMouseListener(new MouseAdapter()
{
public void mousePressed(MouseEvent e)
{
String temp;
if(flag==0)
{
value1=value1+6;
temp=value1;
}
else
{
value2=value2+6;
temp=value2;
}
text.setText(temp);
}
});
final JButton button7=new JButton("7");
c.add(button7);
button7.addMouseListener(new MouseAdapter()
{
public void mousePressed(MouseEvent e)
{
String temp;
if(flag==0)
{
value1=value1+7;
temp=value1;
}
else
{
value2=value2+7;
temp=value2;
}
text.setText(temp);
}
});
final JButton button8=new JButton("8");
c.add(button8);
button8.addMouseListener(new MouseAdapter()
{
public void mousePressed(MouseEvent e)
{
String temp;
if(flag==0)
{
value1=value1+8;
temp=value1;
}
else
{
value2=value2+8;
temp=value2;
}
text.setText(temp);
}
});
final JButton button9=new JButton("9");
c.add(button9);
button9.addMouseListener(new MouseAdapter()
{
public void mousePressed(MouseEvent e)
{
String temp;
if(flag==0)
{
value1=value1+9;
temp=value1;
}
else
{
value2=value2+9;
temp=value2;
}
text.setText(temp);
}
});
final JButton button0=new JButton("0");
c.add(button0);
button0.addMouseListener(new MouseAdapter()
{
public void mousePressed(MouseEvent e)
{
String temp;
if(flag==0)
{
value1=value1+0;
temp=value1;
}
else
{
value2=value2+0;
temp=value2;
}
text.setText(temp);
}
});
final JButton buttonadd=new JButton(" + ");
c.add(buttonadd);
buttonadd.addMouseListener(new MouseAdapter()
{
public void mousePressed(MouseEvent e)
{
flag=1;
fix=1;
flagsum=0;
}
});
final JButton buttonsubtract=new JButton(" - ");
c.add(buttonsubtract);
buttonsubtract.addMouseListener(new MouseAdapter()
{
public void mousePressed(MouseEvent e)
{
flag=1;
fix=2;
flagsum=0;
}
});
final JButton buttoncheng=new JButton(" * ");
c.add(buttoncheng);
buttoncheng.addMouseListener(new MouseAdapter()
{
public void mousePressed(MouseEvent e)
{
flag=1;
fix=3;
flagsum=0;
}
});
final JButton buttonchu=new JButton(" / ");
c.add(buttonchu);
buttonchu.addMouseListener(new MouseAdapter()
{
public void mousePressed(MouseEvent e)
{
flag=1;
flagsum=0;
fix=4;
}
});
final JButton buttonequal=new JButton(" = ");
c.add(buttonequal);
buttonequal.addMouseListener(new MouseAdapter()
{
public void mousePressed(MouseEvent e)
{
double temp1,temp2;
double temp=0;
flagsum=0;
temp1=Double.parseDouble(value1);
temp2=Double.parseDouble(value2);
flag=0;
switch(fix)
{
case 1: temp=temp1+temp2;break;
case 2: temp=temp1-temp2;break;
case 3: temp=temp1*temp2;break;
case 4: temp=temp1/temp2;break;
}
result=Double.valueOf(temp).toString();
value1=result;
value2="";
flag=1;
text.setText(result);
}
});
final JButton buttonpoint=new JButton(".");
c.add(buttonpoint);
buttonpoint.addMouseListener(new MouseAdapter()
{
public void mousePressed(MouseEvent e)
{ if(flagsum==0)
{
String temp;
if(flag==0 )
{
value1=value1+".";
temp=value1;
}
else
{
value2=value2+".";
temp=value2;
}
flagsum=1;
text.setText(temp);
}
}
});
JButton buttonz=new JButton("Start");
c.add(buttonz);
buttonz.addMouseListener(new MouseAdapter()
{
public void mousePressed(MouseEvent e)
{ if(sum%2==1)
{
happy=true;
text.setText("0.");
flag=0;
}
else
{
happy=false;
value1="";
value2="";
text.setText("");
}
text.setEnabled(happy);
button1.setEnabled(happy);
button2.setEnabled(happy);
button3.setEnabled(happy);
button4.setEnabled(happy);
button5.setEnabled(happy);
button6.setEnabled(happy);
button7.setEnabled(happy);
button8.setEnabled(happy);
button9.setEnabled(happy);
button0.setEnabled(happy);
buttonx.setEnabled(happy);
buttony.setEnabled(happy);
buttonadd.setEnabled(happy);
buttonsubtract.setEnabled(happy);
buttonpoint.setEnabled(happy);
buttonequal.setEnabled(happy);
buttoncheng.setEnabled(happy);
buttonchu.setEnabled(happy);
sum++;
}
});
button1.setEnabled(false);
button2.setEnabled(false);
button3.setEnabled(false);
button4.setEnabled(false);
button5.setEnabled(false);
button6.setEnabled(false);
button7.setEnabled(false);
button8.setEnabled(false);
button9.setEnabled(false);
button0.setEnabled(false);
buttonx.setEnabled(false);
buttony.setEnabled(false);
buttonadd.setEnabled(false);
buttonsubtract.setEnabled(false);
buttonpoint.setEnabled(false);
buttonequal.setEnabled(false);
buttoncheng.setEnabled(false);
buttonchu.setEnabled(false);
text.setEnabled(false);
text.setBounds(20, 20, 200, 40);
buttonx.setBounds(20, 60,100, 40);
buttony.setBounds(140, 60,100, 40);
buttonz.setBounds(260, 60,80, 40);
button1.setBounds(20, 120,60, 40);
button2.setBounds(100, 120,60, 40);
button3.setBounds(180, 120,60, 40);
buttonadd.setBounds(260, 120,60, 40);
button4.setBounds(20, 180,60, 40);
button5.setBounds(100, 180,60, 40);
button6.setBounds(180, 180,60, 40);
buttonsubtract.setBounds(260, 180,60, 40);
button7.setBounds(20, 240,60, 40);
button8.setBounds(100, 240,60, 40);
button9.setBounds(180, 240,60, 40);
buttoncheng.setBounds(260,240,60,40);
button0.setBounds(20, 300,60, 40);
buttonpoint.setBounds(100, 300, 60, 40);
buttonequal.setBounds(180,300,60, 40);
buttonchu.setBounds(260, 300,60, 40);
setVisible(true);
}
class MYMouseEvent extends MouseAdapter
{
public void mousePressed(MouseEvent e)
{
value1=e.toString();
text.setText(value1);
}
}
}
class Calutator
{
public static void main(String[] args)
{
new ConstructFrame();
}
}
你自己慢慢的看吧！
关于java String类的substring()和equals()方法
1、public class HelloWorld {
public static void main(String[] args) {
System.out.println("Helloworld");
test();
}
public static void test() {
String s = "10";
String s2 = "1";
System.out.println(s.substring(0, 1)=="1");
System.out.println(s.equals("1"));
System.out.println(s2.substring(0,1)=="1");
System.out.println(s2.equals("1"));
}
}
结果不一样：
1、false "1"在字符串常量区
使用substring...
是重新在堆里创建了一个String对象，见下面源码（return语句）：
public String substring(int beginIndex, int endIndex) {
if (beginIndex 0) {
throw new StringIndexOutOfBoundsException(beginIndex);
}
if (endIndex value.length) {
throw new StringIndexOutOfBoundsException(endIndex);
}
int subLen = endIndex - beginIndex;
if (subLen 0) {
throw new StringIndexOutOfBoundsException(subLen);
}
return ((beginIndex == 0) (endIndex == value.length)) ? this
: new String(value, beginIndex, subLen);
}
"=="比较的是引用变量的内容.
2、"10"跟"1" 使用equals比较..这个方法比较的先是引用，再是比较的内容，可以参考String类的equals方法。 "10"和"1"在字符串常量区肯定不同，比较内容更是不同.
3、看到源码这句了吗：((beginIndex == 0) (endIndex == value.length)) ? this
就是说截取的长度从0开始，末索引是当前字符串长度的时侯，返回它自身. 然后按照上面胡1方式比较。
4、按照2方式比较。
如果还不懂。。请说明。
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