Question

我的目标是阅读一个简单的文本文件，然后输出结果。出于某种原因，我收到错误，因为无法找到指定的文件，即使它位于同一文件夹中。我有点难过为什么它不起作用。

     <!DOCTYPE html>
    <html lang="en">
      <head>
        <meta charset="utf-8">

        <title>Tree Example</title>

        <style>

        .node {
            cursor: pointer;
        }

        .node circle {
          fill: #fff;
          stroke: steelblue;
          stroke-width: 3px;
        }

        .node text {
          font: 12px sans-serif;
        }

        .link {
          fill: none;
          stroke: #ccc;
          stroke-width: 2px;
        }

        </style>

      </head>

      <body>

    <!-- load the d3.js library --> 
    <script src="http://d3js.org/d3.v3.min.js"></script>

    <script>

    var treeData = [
      {
        "name": "Top Level",
        "parent": "null",
        "children": [
          {
            "name": "Level 2: A",
            "parent": "Top Level",
            "children": [
              {
                "name": "Son of A",
                "parent": "Level 2: A"
              },
              {
                "name": "Daughter of A",
                "parent": "Level 2: A"
              }
            ]
          },
          {
            "name": "Level 2: B",
            "parent": "Top Level"
          }
        ]
      }
    ];


    // ************** Generate the tree diagram  *****************
    var margin = {top: 20, right: 120, bottom: 20, left: 120},
        width = 960 - margin.right - margin.left,
        height = 500 - margin.top - margin.bottom;

    var i = 0,
        duration = 750,
        root;

    var tree = d3.layout.tree()
        .size([height, width]);

    var diagonal = d3.svg.diagonal()
        .projection(function(d) { return [d.y, d.x]; });

    var svg = d3.select("body").append("svg")
        .attr("width", width + margin.right + margin.left)
        .attr("height", height + margin.top + margin.bottom)
      .append("g")
        .attr("transform", "translate(" + margin.left + "," + margin.top + ")");

    root = treeData[0];
    root.x0 = height / 2;
    root.y0 = 0;

    update(root);

    d3.select(self.frameElement).style("height", "500px");

    function update(source) {

      // Compute the new tree layout.
      var nodes = tree.nodes(root).reverse(),
          links = tree.links(nodes);

      // Normalize for fixed-depth.
      nodes.forEach(function(d) { d.y = d.depth * 180; });

      // Update the nodes…
      var node = svg.selectAll("g.node")
          .data(nodes, function(d) { return d.id || (d.id = ++i); });
       
      // Enter any new nodes at the parent's previous position.
      var nodeEnter = node.enter().append("g")
          .attr("class", "node")
          .attr("transform", function(d) { return "translate(" + source.y0 + "," + source.x0 + ")"; })
          ;
     
      nodeEnter.append("circle")
          .attr("r", 1e-6)
          .style("fill", function(d) { return d._children ? "lightsteelblue" : "#fff"; }).on("click", click);
      
      nodeEnter.append("text")
          .attr("x", function(d) { return d.children || d._children ? -13 : 13; })
          .attr("dy", ".35em")
          .attr("text-anchor", function(d) { return d.children || d._children ? "end" : "start"; })
          .text(function(d) { return d.name; })
          .style("fill-opacity", 1e-6);
      nodeEnter.append("foreignObject")
      .html("<input type=checkbox id='check'></input>").style("position", "absolute")
      .style("top", "320")
      .style("left", "150")
    ;//use foreignObject to get check boxes
      // Transition nodes to their new position.
      var nodeUpdate = node.transition()
          .duration(duration)
          .attr("transform", function(d) { return "translate(" + d.y + "," + d.x + ")"; });

      nodeUpdate.select("circle")
          .attr("r", 10)
          .style("fill", function(d) { return d._children ? "lightsteelblue" : "#fff"; });

      nodeUpdate.select("text")
          .style("fill-opacity", 1);

      // Transition exiting nodes to the parent's new position.
      var nodeExit = node.exit().transition()
          .duration(duration)
          .attr("transform", function(d) { return "translate(" + source.y + "," + source.x + ")"; })
          .remove();

      nodeExit.select("circle")
          .attr("r", 1e-6);

      nodeExit.select("text")
          .style("fill-opacity", 1e-6);

      // Update the links…
      var link = svg.selectAll("path.link")
          .data(links, function(d) { return d.target.id; });

      // Enter any new links at the parent's previous position.
      link.enter().insert("path", "g")
          .attr("class", "link")
          .attr("d", function(d) {
            var o = {x: source.x0, y: source.y0};
            return diagonal({source: o, target: o});
          });

      // Transition links to their new position.
      link.transition()
          .duration(duration)
          .attr("d", diagonal);

      // Transition exiting nodes to the parent's new position.
      link.exit().transition()
          .duration(duration)
          .attr("d", function(d) {
            var o = {x: source.x, y: source.y};
            return diagonal({source: o, target: o});
          })
          .remove();

      // Stash the old positions for transition.
      nodes.forEach(function(d) {
        d.x0 = d.x;
        d.y0 = d.y;
      });
    }

    // Toggle children on click.
    function click(d) {
      if (d.children) {
        d._children = d.children;
        d.children = null;
      } else {
        d.children = d._children;
        d._children = null;
      }
      update(d);
    }

    </script>

      </body>
    </html>

Answer 1

你在说哪个文件夹？如果从Eclipse执行应用程序，则文本文件必须位于.project，.classpath等文件和文件夹所在的目录中。

Answer 2

该文件需要立即在项目文件夹中。如果它仍然无法工作，您可以使用绝对路径而不是相对路径作为替代。比如例如D:\\test.txt

Answer 3

以下是使用JOptionPane

以图形方式选择文件的方法

ArrayList<String> lines = new ArrayList<>();

JOptionPane.showMessageDialog(null, "Please choose a file");        
JFileChooser input = new JFileChooser();
int a = input.showOpenDialog(null);
String file = "";

if (a == JFileChooser.APPROVE_OPTION) {
    File selectedFile = input.getSelectedFile();
    file = selectedFile.getPath();
}

//use file input to read in line one at a time
FileInputStream fstream = new FileInputStream(file);
DataInputStream in = new DataInputStream(fstream);
BufferedReader br = new BufferedReader(new InputStreamReader(in));
String line;
while ((line = br.readLine()) != null) {
    lines.add(line);
}

while循环用于读取文本文件错误java

3 个答案: