如何从文本视图中获取文本 [英] how to get text from textview

问题描述

如果我以这种方式在 textview 中设置了文本，这不是问题:

if I have set text in textview in such way, which is not problem:

  tv.setText("" + ANS[i]);

这只是从这种方式获得.

this simply getting from this way.

     String a = tv.getText().toString();
     int A = Integer.parseInt(a);

但是如果在 textView 中设置值.

But in case of setting value in textView.

 tv1.setText("  " + X[i] + "
" + "+" + " " + Y[i]);

是这样的

              5
             +9

我有问题，这个值如何获取.

I have problem , this value how to get.

推荐答案

我没有对此进行测试 - 但它应该能让您大致了解您需要采取的方向.

I haven't tested this - but it should give you a general idea of the direction you need to take.

为此，我将假设关于 TextView 的文本的一些事情:

For this to work, I'm going to assume a few things about the text of the TextView:

1. TextView 由 " " 分隔的行组成.
2. 第一行将不包含运算符(+、-、* 或/).
3. 在第一行之后，TextView 中可以有可变数量的行，其中都包含 one 运算符和 one 数字.
4. 操作符总是一行的第一个Char.

1. The TextView consists of lines delimited with " ".
2. The first line will not include an operator (+, -, * or /).
3. After the first line there can be a variable number of lines in the TextView which will all include one operator and one number.
4. An operator will allways be the first Char of a line.

首先我们得到文本:

String input = tv1.getText().toString();

然后我们将其拆分为每一行:

Then we split it up for each line:

String[] lines = input.split( "
" );

现在我们需要计算总值:

Now we need to calculate the total value:

int total = Integer.parseInt( lines[0].trim() ); //We know this is a number.

for( int i = 1; i < lines.length(); i++ ) {
   total = calculate( lines[i].trim(), total );
}

方法calculate应该是这样的，假设我们知道一行的第一个Char是操作符:

The method calculate should look like this, assuming that we know the first Char of a line is the operator:

private int calculate( String input, int total ) {
   switch( input.charAt( 0 ) )
      case '+':
         return total + Integer.parseInt( input.substring( 1, input.length() );
      case '-':
         return total - Integer.parseInt( input.substring( 1, input.length() );             
      case '*':
         return total * Integer.parseInt( input.substring( 1, input.length() );             
      case '/':
         return total / Integer.parseInt( input.substring( 1, input.length() );
}

<小时>

编辑

所以上面在下面的评论中说明了从左到右"的计算，忽略了正常的顺序(+和/在+和-之前).

So the above as stated in the comment below does "left-to-right" calculation, ignoring the normal order ( + and / before + and -).

以下是正确的计算方式:

The following does the calculation the right way:

String input = tv1.getText().toString();
input = input.replace( "
", "" );
input = input.replace( " ", "" );
int total = getValue( input );

getValue 方法是一个递归方法，应该如下所示:

The method getValue is a recursive method and it should look like this:

private int getValue( String line ) {
  int value = 0;

  if( line.contains( "+" ) ) {
    String[] lines = line.split( "\+" );
    value += getValue( lines[0] );

    for( int i = 1; i < lines.length; i++ )
      value += getValue( lines[i] );

    return value;
  }

  if( line.contains( "-" ) ) {
    String[] lines = line.split( "\-" );
    value += getValue( lines[0] );

    for( int i = 1; i < lines.length; i++ )
      value -= getValue( lines[i] );

    return value;
  }

  if( line.contains( "*" ) ) {
    String[] lines = line.split( "\*" );
    value += getValue( lines[0] );

    for( int i = 1; i < lines.length; i++ )
      value *= getValue( lines[i] );

    return value;
  }

  if( line.contains( "/" ) ) {
    String[] lines = line.split( "\/" );
    value += getValue( lines[0] );

    for( int i = 1; i < lines.length; i++ )
      value /= getValue( lines[i] );

    return value;
  }

  return Integer.parseInt( line );
}

递归方法无法处理的特殊情况:

Special cases that the recursive method does not handle:

• 如果第一个数字是负数，例如-3+5*8.
• 双运算符，例如3*-6 或 5/-4.

此外，我们使用 Integers 在某些情况下可能会产生一些奇怪"的结果，例如5/3 = 1.

Also the fact the we're using Integers might give some "odd" results in some cases as e.g. 5/3 = 1.

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