Question

J2ME中的TextBox

TextBox构造方法中的静态字段TextField.DECIMAL是怎么实现控制TextBox中的内容的？
Java中通过静态字段实现控制好像用的很多 具体怎么实现的呢?
新手 麻烦说的尽量详细点
谢谢！！

Answer 1

这是源代码 具体怎么实现的我也不是很明白：期待高手解决
constraints 就是传递过来的那个参数
protected boolean buildInputModes(int constraints, int modifiers, String dMode, String[] aMode)
{
boolean ret = true;
this.capWord = (this.capSentence = 0);

if ((constraints == 2) || (constraints == 5) || (constraints == 3))
{
this.defaultMode = 3;
this.allowedModesNum = 1;
this.allowedModes[0] = 3;
}
else if ((constraints == 1) || (constraints == 4))
{
this.defaultMode = 2;
this.allowedModesNum = 4;
this.allowedModes[0] = 2;
this.allowedModes[1] = 1;
this.allowedModes[2] = 3;
this.allowedModes[3] = 4;
}
else {
if (constraints != 0) {
dMode = null;
aMode = null;
}

Vector uniqueModes = new Vector(NUM_INPUT_MODES);

if ((dMode == null) && (aMode == null)) {
this.allowedModesNum = this.supportedInputModes.length;
System.arraycopy(this.supportedInputModes, 0, this.allowedModes, 0, this.allowedModesNum);

this.defaultMode = this.allowedModes[0];
} else {
if ((dMode == null) && (aMode != null)) {
dMode = aMode[0];
}
if ((dMode != null) && (aMode == null)) {
aMode = new String[this.supportedCharSubset.length];
System.arraycopy(this.supportedCharSubset, 0, aMode, 0, this.supportedCharSubset.length);
}

for (int i = 0; i < this.inputModeConvTable.length; ++i) {
if (!(((String)this.inputModeConvTable[i][0]).equals(dMode)))
continue;
this.defaultMode = ((Integer)this.inputModeConvTable[i][1]).intValue();

break;
}

for (int j = 0; j < this.inputModeConvTable.length; ++j) {
for (int i = 0; i < aMode.length; ++i) {
Integer imode = (Integer)this.inputModeConvTable[i][1];
if ((!(((String)this.inputModeConvTable[j][0]).equals(aMode[i]))) || (uniqueModes.indexOf(imode) != -1))
continue;
uniqueModes.addElement(imode);
}

}

this.allowedModesNum = uniqueModes.size();
for (int i = 0; i < this.allowedModesNum; ++i) {
this.allowedModes[i] = ((Integer)uniqueModes.elementAt(i)).intValue();
}

if (this.defaultMode == 0) {
this.defaultMode = this.allowedModes[0];
}

}

this.capWord = ((modifiers & 0x100000) == 1048576);

this.capSentence = ((modifiers & 0x200000) == 2097152);

if ((this.capWord) || (this.capSentence)) {
this.defaultMode = 1;
}
}

this.oldInputMode = this.defaultMode;
this.inputMode = this.defaultMode;

return ret;
}

Answer 2

其实 TextField 中封装了很多的方法,DECIMAL静态字段只是一个开关的作用,中间的过程你可以理解为 很多的 if 语句判断 , 如果判断条件和DECIMAL相等就只能输入数字,其他输入值就不显示.
哈哈 我也是新手共同进步吧